Merge branch 'master' into nftables

internal/configuration/settings/amneziawg.go

@@ -0,0 +1,234 @@
+package settings
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/qdm12/gosettings"
+	"github.com/qdm12/gosettings/reader"
+	"github.com/qdm12/gotree"
+)
+
+type AmneziaWg struct {
+	// Wireguard contains the configuration for Wireguard, given
+	// AmneziaWg is based on Wireguard
+	Wireguard       Wireguard `json:"wireguard"`
+	JunkPacketCount *uint16   `json:"junk_packet_count"`
+	JunkPacketMin   *uint16   `json:"junk_packet_min"`
+	JunkPacketMax   *uint16   `json:"junk_packet_max"`
+	PaddingS1       *uint16   `json:"padding_s1"`
+	PaddingS2       *uint16   `json:"padding_s2"`
+	PaddingS3       *uint16   `json:"padding_s3"`
+	PaddingS4       *uint16   `json:"padding_s4"`
+	HeaderH1        *string   `json:"header_h1"`
+	HeaderH2        *string   `json:"header_h2"`
+	HeaderH3        *string   `json:"header_h3"`
+	HeaderH4        *string   `json:"header_h4"`
+	InitPacketI1    *string   `json:"init_packet_i1"`
+	InitPacketI2    *string   `json:"init_packet_i2"`
+	InitPacketI3    *string   `json:"init_packet_i3"`
+	InitPacketI4    *string   `json:"init_packet_i4"`
+	InitPacketI5    *string   `json:"init_packet_i5"`
+}
+
+func (a *AmneziaWg) read(r *reader.Reader) (err error) {
+	const amneziawg = true
+	err = a.Wireguard.read(r, amneziawg)
+	if err != nil {
+		return err // do not wrap this error
+	}
+
+	uint16Fields := map[string]**uint16{
+		"AMNEZIAWG_JC":   &a.JunkPacketCount,
+		"AMNEZIAWG_JMIN": &a.JunkPacketMin,
+		"AMNEZIAWG_JMAX": &a.JunkPacketMax,
+		"AMNEZIAWG_S1":   &a.PaddingS1,
+		"AMNEZIAWG_S2":   &a.PaddingS2,
+		"AMNEZIAWG_S3":   &a.PaddingS3,
+		"AMNEZIAWG_S4":   &a.PaddingS4,
+	}
+	for key, dst := range uint16Fields {
+		*dst, err = r.Uint16Ptr(key)
+		if err != nil {
+			return err
+		}
+	}
+	stringFields := map[string]**string{
+		"AMNEZIAWG_H1": &a.HeaderH1,
+		"AMNEZIAWG_H2": &a.HeaderH2,
+		"AMNEZIAWG_H3": &a.HeaderH3,
+		"AMNEZIAWG_H4": &a.HeaderH4,
+		"AMNEZIAWG_I1": &a.InitPacketI1,
+		"AMNEZIAWG_I2": &a.InitPacketI2,
+		"AMNEZIAWG_I3": &a.InitPacketI3,
+		"AMNEZIAWG_I4": &a.InitPacketI4,
+		"AMNEZIAWG_I5": &a.InitPacketI5,
+	}
+	opt := reader.ForceLowercase(false)
+	for key, dst := range stringFields {
+		*dst = r.Get(key, opt)
+	}
+	return nil
+}
+
+func (a AmneziaWg) copy() (copied AmneziaWg) {
+	return AmneziaWg{
+		Wireguard:       a.Wireguard.copy(),
+		JunkPacketCount: gosettings.CopyPointer(a.JunkPacketCount),
+		JunkPacketMin:   gosettings.CopyPointer(a.JunkPacketMin),
+		JunkPacketMax:   gosettings.CopyPointer(a.JunkPacketMax),
+		PaddingS1:       gosettings.CopyPointer(a.PaddingS1),
+		PaddingS2:       gosettings.CopyPointer(a.PaddingS2),
+		PaddingS3:       gosettings.CopyPointer(a.PaddingS3),
+		PaddingS4:       gosettings.CopyPointer(a.PaddingS4),
+		HeaderH1:        gosettings.CopyPointer(a.HeaderH1),
+		HeaderH2:        gosettings.CopyPointer(a.HeaderH2),
+		HeaderH3:        gosettings.CopyPointer(a.HeaderH3),
+		HeaderH4:        gosettings.CopyPointer(a.HeaderH4),
+		InitPacketI1:    gosettings.CopyPointer(a.InitPacketI1),
+		InitPacketI2:    gosettings.CopyPointer(a.InitPacketI2),
+		InitPacketI3:    gosettings.CopyPointer(a.InitPacketI3),
+		InitPacketI4:    gosettings.CopyPointer(a.InitPacketI4),
+		InitPacketI5:    gosettings.CopyPointer(a.InitPacketI5),
+	}
+}
+
+func (a *AmneziaWg) overrideWith(other AmneziaWg) {
+	a.Wireguard.overrideWith(other.Wireguard)
+	a.JunkPacketCount = gosettings.OverrideWithPointer(a.JunkPacketCount, other.JunkPacketCount)
+	a.JunkPacketMin = gosettings.OverrideWithPointer(a.JunkPacketMin, other.JunkPacketMin)
+	a.JunkPacketMax = gosettings.OverrideWithPointer(a.JunkPacketMax, other.JunkPacketMax)
+	a.PaddingS1 = gosettings.OverrideWithPointer(a.PaddingS1, other.PaddingS1)
+	a.PaddingS2 = gosettings.OverrideWithPointer(a.PaddingS2, other.PaddingS2)
+	a.PaddingS3 = gosettings.OverrideWithPointer(a.PaddingS3, other.PaddingS3)
+	a.PaddingS4 = gosettings.OverrideWithPointer(a.PaddingS4, other.PaddingS4)
+	a.HeaderH1 = gosettings.OverrideWithPointer(a.HeaderH1, other.HeaderH1)
+	a.HeaderH2 = gosettings.OverrideWithPointer(a.HeaderH2, other.HeaderH2)
+	a.HeaderH3 = gosettings.OverrideWithPointer(a.HeaderH3, other.HeaderH3)
+	a.HeaderH4 = gosettings.OverrideWithPointer(a.HeaderH4, other.HeaderH4)
+	a.InitPacketI1 = gosettings.OverrideWithPointer(a.InitPacketI1, other.InitPacketI1)
+	a.InitPacketI2 = gosettings.OverrideWithPointer(a.InitPacketI2, other.InitPacketI2)
+	a.InitPacketI3 = gosettings.OverrideWithPointer(a.InitPacketI3, other.InitPacketI3)
+	a.InitPacketI4 = gosettings.OverrideWithPointer(a.InitPacketI4, other.InitPacketI4)
+	a.InitPacketI5 = gosettings.OverrideWithPointer(a.InitPacketI5, other.InitPacketI5)
+}
+
+func (a *AmneziaWg) setDefaults(vpnProvider string) {
+	a.Wireguard.setDefaults(vpnProvider)
+	a.Wireguard.Implementation = "userspace" // unused except in logs
+	a.JunkPacketCount = gosettings.DefaultPointer(a.JunkPacketCount, 0)
+	a.JunkPacketMin = gosettings.DefaultPointer(a.JunkPacketMin, 0)
+	a.JunkPacketMax = gosettings.DefaultPointer(a.JunkPacketMax, 0)
+	a.PaddingS1 = gosettings.DefaultPointer(a.PaddingS1, 0)
+	a.PaddingS2 = gosettings.DefaultPointer(a.PaddingS2, 0)
+	a.PaddingS3 = gosettings.DefaultPointer(a.PaddingS3, 0)
+	a.PaddingS4 = gosettings.DefaultPointer(a.PaddingS4, 0)
+	a.HeaderH1 = gosettings.DefaultPointer(a.HeaderH1, "")
+	a.HeaderH2 = gosettings.DefaultPointer(a.HeaderH2, "")
+	a.HeaderH3 = gosettings.DefaultPointer(a.HeaderH3, "")
+	a.HeaderH4 = gosettings.DefaultPointer(a.HeaderH4, "")
+	a.InitPacketI1 = gosettings.DefaultPointer(a.InitPacketI1, "")
+	a.InitPacketI2 = gosettings.DefaultPointer(a.InitPacketI2, "")
+	a.InitPacketI3 = gosettings.DefaultPointer(a.InitPacketI3, "")
+	a.InitPacketI4 = gosettings.DefaultPointer(a.InitPacketI4, "")
+	a.InitPacketI5 = gosettings.DefaultPointer(a.InitPacketI5, "")
+}
+
+func (a AmneziaWg) toLinesNode() (node *gotree.Node) {
+	node = gotree.New("AmneziaWG settings:")
+	node.AppendNode(a.Wireguard.toLinesNode())
+
+	uintFields := []struct {
+		key string
+		val *uint16
+	}{
+		{"JC", a.JunkPacketCount},
+		{"JMIN", a.JunkPacketMin},
+		{"JMAX", a.JunkPacketMax},
+		{"S1", a.PaddingS1},
+		{"S2", a.PaddingS2},
+		{"S3", a.PaddingS3},
+		{"S4", a.PaddingS4},
+	}
+	for _, f := range uintFields {
+		node.Appendf("%s: %d", f.key, *f.val)
+	}
+
+	stringFields := []struct {
+		key string
+		val *string
+	}{
+		{"H1", a.HeaderH1},
+		{"H2", a.HeaderH2},
+		{"H3", a.HeaderH3},
+		{"H4", a.HeaderH4},
+		{"I1", a.InitPacketI1},
+		{"I2", a.InitPacketI2},
+		{"I3", a.InitPacketI3},
+		{"I4", a.InitPacketI4},
+		{"I5", a.InitPacketI5},
+	}
+	for _, f := range stringFields {
+		node.Appendf("%s: %s", f.key, *f.val)
+	}
+
+	return node
+}
+
+func (a AmneziaWg) validate(vpnProvider string, ipv6Supported bool) error {
+	const amneziaWG = true
+	err := a.Wireguard.validate(vpnProvider, ipv6Supported, amneziaWG)
+	if err != nil {
+		return fmt.Errorf("wireguard settings: %w", err)
+	}
+
+	if *a.JunkPacketCount == 0 {
+		if *a.JunkPacketMin != 0 || *a.JunkPacketMax != 0 {
+			return fmt.Errorf("junk packet count must be set when junk packet min or max is set: "+
+				"jc=%d and jmin=%d and jmax=%d", a.JunkPacketCount, *a.JunkPacketMin, *a.JunkPacketMax)
+		}
+	} else {
+		if *a.JunkPacketMin == 0 || *a.JunkPacketMax == 0 {
+			return fmt.Errorf("junk packet min and max must be set when junk packet count is set: "+
+				"jc=%d and jmin=%d and jmax=%d", a.JunkPacketCount, *a.JunkPacketMin, *a.JunkPacketMax)
+		} else if *a.JunkPacketMin > *a.JunkPacketMax {
+			return fmt.Errorf("junk packet minimum must be lower than or equal to maximum: "+
+				"jmin=%d and jmax=%d", *a.JunkPacketMin, *a.JunkPacketMax)
+		}
+	}
+
+	nameToHeaderRange := map[string]string{
+		"h1": *a.HeaderH1,
+		"h2": *a.HeaderH2,
+		"h3": *a.HeaderH3,
+		"h4": *a.HeaderH4,
+	}
+	for name, headerRange := range nameToHeaderRange {
+		if headerRange == "" {
+			continue
+		}
+		fields := strings.Split(headerRange, "-")
+		switch len(fields) {
+		case 1:
+			_, err := strconv.Atoi(fields[0])
+			if err != nil {
+				return fmt.Errorf("header range is malformed: "+
+					"%s value %s is not a number", name, headerRange)
+			}
+		case 2: //nolint:mnd
+			for _, field := range fields {
+				_, err := strconv.Atoi(field)
+				if err != nil {
+					return fmt.Errorf("header range is malformed: "+
+						"%s value %s is not a valid range", name, headerRange)
+				}
+			}
+		default:
+			return fmt.Errorf("header range is malformed: "+
+				"%s value %s must be in the form n or n-m", name, headerRange)
+		}
+	}
+
+	return nil
+}

internal/configuration/settings/boringpoll.go

@@ -0,0 +1,51 @@
+package settings
+
+import (
+	"github.com/qdm12/gosettings"
+	"github.com/qdm12/gosettings/reader"
+	"github.com/qdm12/gotree"
+)
+
+type BoringPoll struct {
+	GluetunCom *bool
+}
+
+func (b BoringPoll) validate() error {
+	return nil
+}
+
+func (b BoringPoll) Copy() BoringPoll {
+	return BoringPoll{
+		GluetunCom: gosettings.CopyPointer(b.GluetunCom),
+	}
+}
+
+func (b *BoringPoll) overrideWith(other BoringPoll) {
+	b.GluetunCom = gosettings.OverrideWithPointer(b.GluetunCom, other.GluetunCom)
+}
+
+func (b *BoringPoll) setDefaults() {
+	b.GluetunCom = gosettings.DefaultPointer(b.GluetunCom, false)
+}
+
+func (b BoringPoll) String() string {
+	return b.toLinesNode().String()
+}
+
+func (b BoringPoll) toLinesNode() *gotree.Node {
+	if !*b.GluetunCom {
+		return nil
+	}
+
+	node := gotree.New("Boring-poll settings:")
+	node.Append("gluetun.com: on")
+	return node
+}
+
+func (b *BoringPoll) read(r *reader.Reader) (err error) {
+	b.GluetunCom, err = r.BoolPtr("BORINGPOLL_GLUETUNCOM")
+	if err != nil {
+		return err
+	}
+	return nil
+}

internal/configuration/settings/deprecated.go

@@ -1,10 +1,10 @@
 package settings
 
 import (
+	"maps"
 	"slices"
 
 	"github.com/qdm12/gosettings/reader"
-	"golang.org/x/exp/maps"
 )
 
 func readObsolete(r *reader.Reader) (warnings []string) {
@@ -14,8 +14,11 @@ func readObsolete(r *reader.Reader) (warnings []string) {
 		"DOT_VALIDATION_LOGLEVEL":      "DOT_VALIDATION_LOGLEVEL is obsolete because DNSSEC validation is not implemented.",
 		"HEALTH_VPN_DURATION_INITIAL":  "HEALTH_VPN_DURATION_INITIAL is obsolete",
 		"HEALTH_VPN_DURATION_ADDITION": "HEALTH_VPN_DURATION_ADDITION is obsolete",
+		"DNS_KEEP_NAMESERVER": "DNS_KEEP_NAMESERVER is obsolete because you should use the built-in server which now " +
+			"forwards local names to private DNS resolvers found in /etc/resolv.conf at container start",
+		"BLOCK_SURVEILLANCE": "BLOCK_SURVEILLANCE is obsolete because its DNS block lists are not longer maintained",
 	}
-	sortedKeys := maps.Keys(keyToMessage)
+	sortedKeys := slices.Collect(maps.Keys(keyToMessage))
 	slices.Sort(sortedKeys)
 	warnings = make([]string, 0, len(keyToMessage))
 	for _, key := range sortedKeys {

internal/configuration/settings/dns.go

@@ -1,7 +1,6 @@
 package settings
 
 import (
-	"errors"
 	"fmt"
 	"net/netip"
 	"time"
@@ -13,20 +12,28 @@ import (
 	"github.com/qdm12/gotree"
 )
 
+const (
+	DNSUpstreamTypeDot   = "dot"
+	DNSUpstreamTypeDoh   = "doh"
+	DNSUpstreamTypePlain = "plain"
+)
+
 // DNS contains settings to configure DNS.
 type DNS struct {
-	// ServerEnabled is true if the server should be running
-	// and used. It defaults to true, and cannot be nil
-	// in the internal state.
-	ServerEnabled *bool
-	// UpstreamType can be dot or plain, and defaults to dot.
+	// ServerEnabled indicates if the DNS server should be enabled.
+	// It defaults to true and cannot be nil in the internal state.
+	ServerEnabled *bool `json:"enabled"`
+	// UpstreamType can be [DNSUpstreamTypeDot], [DNSUpstreamTypeDoh]
+	// or [DNSUpstreamTypePlain]. It defaults to [DNSUpstreamTypeDot].
 	UpstreamType string `json:"upstream_type"`
 	// UpdatePeriod is the period to update DNS block lists.
 	// It can be set to 0 to disable the update.
 	// It defaults to 24h and cannot be nil in
 	// the internal state.
 	UpdatePeriod *time.Duration
-	// Providers is a list of DNS providers
+	// Providers is a list of DNS providers.
+	// It defaults to ["cloudflare"] and is ignored if the UpstreamType is
+	// [DNSUpstreamTypePlain] and the UpstreamPlainAddresses field is set.
 	Providers []string `json:"providers"`
 	// Caching is true if the server should cache
 	// DNS responses.
@@ -36,49 +43,55 @@ type DNS struct {
 	// Blacklist contains settings to configure the filter
 	// block lists.
 	Blacklist DNSBlacklist
-	// ServerAddress is the DNS server to use inside
-	// the Go program and for the system.
-	// It defaults to '127.0.0.1' to be used with the
-	// local server. It cannot be the zero value in the internal
-	// state.
-	ServerAddress netip.Addr
-	// KeepNameserver is true if the existing DNS server
-	// found in /etc/resolv.conf should be used
-	// Note setting this to true will likely DNS traffic
-	// outside the VPN tunnel since it would go through
-	// the local DNS server of your Docker/Kubernetes
-	// configuration, which is likely not going through the tunnel.
-	// This will also disable the DNS forwarder server and the
-	// `ServerAddress` field will be ignored.
-	// It defaults to false and cannot be nil in the
-	// internal state.
-	KeepNameserver *bool
+	// UpstreamPlainAddresses are the upstream plaintext DNS resolver
+	// addresses to use by the built-in DNS server forwarder.
+	// Note, if the upstream type is [dnsUpstreamTypePlain] and this field is set,
+	// the Providers field is ignored.
+	UpstreamPlainAddresses []netip.AddrPort
 }
 
-var (
-	ErrDNSUpstreamTypeNotValid = errors.New("DNS upstream type is not valid")
-	ErrDNSUpdatePeriodTooShort = errors.New("update period is too short")
-)
-
 func (d DNS) validate() (err error) {
-	if !helpers.IsOneOf(d.UpstreamType, "dot", "doh", "plain") {
-		return fmt.Errorf("%w: %s", ErrDNSUpstreamTypeNotValid, d.UpstreamType)
+	if !helpers.IsOneOf(d.UpstreamType, DNSUpstreamTypeDot, DNSUpstreamTypeDoh, DNSUpstreamTypePlain) {
+		return fmt.Errorf("DNS upstream type is not valid: %s", d.UpstreamType)
 	}
 
-	const minUpdatePeriod = 30 * time.Second
-	if *d.UpdatePeriod != 0 && *d.UpdatePeriod < minUpdatePeriod {
-		return fmt.Errorf("%w: %s must be bigger than %s",
-			ErrDNSUpdatePeriodTooShort, *d.UpdatePeriod, minUpdatePeriod)
-	}
-
-	providers := provider.NewProviders()
-	for _, providerName := range d.Providers {
-		_, err := providers.Get(providerName)
+	if !*d.ServerEnabled {
+		err = d.validateForServerOff()
 		if err != nil {
 			return err
 		}
 	}
 
+	const minUpdatePeriod = 30 * time.Second
+	if *d.UpdatePeriod != 0 && *d.UpdatePeriod < minUpdatePeriod {
+		return fmt.Errorf("update period is too short: %s must be bigger than %s",
+			*d.UpdatePeriod, minUpdatePeriod)
+	}
+
+	if d.UpstreamType == DNSUpstreamTypePlain {
+		selectedHasPlainIPv4, selectedHasPlainIPv6 := false, false
+		for _, addrPort := range d.UpstreamPlainAddresses {
+			if !selectedHasPlainIPv4 && addrPort.Addr().Is4() {
+				selectedHasPlainIPv4 = true
+			}
+			if !selectedHasPlainIPv6 && addrPort.Addr().Is6() {
+				selectedHasPlainIPv6 = true
+			}
+			if selectedHasPlainIPv4 && selectedHasPlainIPv6 {
+				break
+			}
+		}
+		switch {
+		case *d.IPv6 && !selectedHasPlainIPv6:
+			return fmt.Errorf("upstream plain addresses do not contain any IPv6 address: "+
+				"in %d addresses", len(d.UpstreamPlainAddresses))
+		case !*d.IPv6 && !selectedHasPlainIPv4:
+			return fmt.Errorf("upstream plain addresses do not contain any IPv4 address: "+
+				"in %d addresses", len(d.UpstreamPlainAddresses))
+		}
+	}
+	// Note: all DNS built in providers have both IPv4 and IPv6 addresses for all modes
+
 	err = d.Blacklist.validate()
 	if err != nil {
 		return err
@@ -87,17 +100,33 @@ func (d DNS) validate() (err error) {
 	return nil
 }
 
+func (d DNS) validateForServerOff() (err error) {
+	switch {
+	case d.UpstreamType != DNSUpstreamTypePlain:
+		return fmt.Errorf("upstream type %s must be %s if the built-in DNS server is disabled",
+			d.UpstreamType, DNSUpstreamTypePlain)
+	case len(d.UpstreamPlainAddresses) == 0:
+		return fmt.Errorf("if DNS is disabled, at least one upstream plain address must be set")
+	}
+	for _, addrPort := range d.UpstreamPlainAddresses {
+		const defaultDNSPort = 53
+		if addrPort.Port() != defaultDNSPort {
+			return fmt.Errorf("invalid DNS port in %s: must be %d", addrPort, defaultDNSPort)
+		}
+	}
+	return nil
+}
+
 func (d *DNS) Copy() (copied DNS) {
 	return DNS{
-		ServerEnabled:  gosettings.CopyPointer(d.ServerEnabled),
-		UpstreamType:   d.UpstreamType,
-		UpdatePeriod:   gosettings.CopyPointer(d.UpdatePeriod),
-		Providers:      gosettings.CopySlice(d.Providers),
-		Caching:        gosettings.CopyPointer(d.Caching),
-		IPv6:           gosettings.CopyPointer(d.IPv6),
-		Blacklist:      d.Blacklist.copy(),
-		ServerAddress:  d.ServerAddress,
-		KeepNameserver: gosettings.CopyPointer(d.KeepNameserver),
+		ServerEnabled:          gosettings.CopyPointer(d.ServerEnabled),
+		UpstreamType:           d.UpstreamType,
+		UpdatePeriod:           gosettings.CopyPointer(d.UpdatePeriod),
+		Providers:              gosettings.CopySlice(d.Providers),
+		Caching:                gosettings.CopyPointer(d.Caching),
+		IPv6:                   gosettings.CopyPointer(d.IPv6),
+		Blacklist:              d.Blacklist.copy(),
+		UpstreamPlainAddresses: gosettings.CopySlice(d.UpstreamPlainAddresses),
 	}
 }
 
@@ -112,41 +141,29 @@ func (d *DNS) overrideWith(other DNS) {
 	d.Caching = gosettings.OverrideWithPointer(d.Caching, other.Caching)
 	d.IPv6 = gosettings.OverrideWithPointer(d.IPv6, other.IPv6)
 	d.Blacklist.overrideWith(other.Blacklist)
-	d.ServerAddress = gosettings.OverrideWithValidator(d.ServerAddress, other.ServerAddress)
-	d.KeepNameserver = gosettings.OverrideWithPointer(d.KeepNameserver, other.KeepNameserver)
+	d.UpstreamPlainAddresses = gosettings.OverrideWithSlice(d.UpstreamPlainAddresses, other.UpstreamPlainAddresses)
 }
 
 func (d *DNS) setDefaults() {
 	d.ServerEnabled = gosettings.DefaultPointer(d.ServerEnabled, true)
-	d.UpstreamType = gosettings.DefaultComparable(d.UpstreamType, "dot")
+	defaultUpstreamType := DNSUpstreamTypeDot
+	if !*d.ServerEnabled {
+		defaultUpstreamType = DNSUpstreamTypePlain
+	}
+	d.UpstreamType = gosettings.DefaultComparable(d.UpstreamType, defaultUpstreamType)
 	const defaultUpdatePeriod = 24 * time.Hour
 	d.UpdatePeriod = gosettings.DefaultPointer(d.UpdatePeriod, defaultUpdatePeriod)
-	d.Providers = gosettings.DefaultSlice(d.Providers, []string{
-		provider.Cloudflare().Name,
-	})
+	d.UpstreamPlainAddresses = gosettings.DefaultSlice(d.UpstreamPlainAddresses, []netip.AddrPort{})
+	d.Providers = gosettings.DefaultSlice(d.Providers, defaultDNSProviders())
 	d.Caching = gosettings.DefaultPointer(d.Caching, true)
 	d.IPv6 = gosettings.DefaultPointer(d.IPv6, false)
 	d.Blacklist.setDefaults()
-	d.ServerAddress = gosettings.DefaultValidator(d.ServerAddress,
-		netip.AddrFrom4([4]byte{127, 0, 0, 1}))
-	d.KeepNameserver = gosettings.DefaultPointer(d.KeepNameserver, false)
 }
 
-func (d DNS) GetFirstPlaintextIPv4() (ipv4 netip.Addr) {
-	localhost := netip.AddrFrom4([4]byte{127, 0, 0, 1})
-	if d.ServerAddress.Compare(localhost) != 0 && d.ServerAddress.Is4() {
-		return d.ServerAddress
+func defaultDNSProviders() []string {
+	return []string{
+		provider.Cloudflare().Name,
 	}
-
-	providers := provider.NewProviders()
-	provider, err := providers.Get(d.Providers[0])
-	if err != nil {
-		// Settings should be validated before calling this function,
-		// so an error happening here is a programming error.
-		panic(err)
-	}
-
-	return provider.Plain.IPv4[0].Addr()
 }
 
 func (d DNS) String() string {
@@ -155,22 +172,33 @@ func (d DNS) String() string {
 
 func (d DNS) toLinesNode() (node *gotree.Node) {
 	node = gotree.New("DNS settings:")
-	node.Appendf("Keep existing nameserver(s): %s", gosettings.BoolToYesNo(d.KeepNameserver))
-	if *d.KeepNameserver {
-		return node
-	}
-	node.Appendf("DNS server address to use: %s", d.ServerAddress)
 
-	node.Appendf("DNS forwarder server enabled: %s", gosettings.BoolToYesNo(d.ServerEnabled))
 	if !*d.ServerEnabled {
+		plainServers := node.Append("Plain DNS servers to use directly:")
+		for _, addr := range d.UpstreamPlainAddresses {
+			plainServers.Append(addr.String())
+		}
 		return node
 	}
 
 	node.Appendf("Upstream resolver type: %s", d.UpstreamType)
 
 	upstreamResolvers := node.Append("Upstream resolvers:")
-	for _, provider := range d.Providers {
-		upstreamResolvers.Append(provider)
+	if len(d.UpstreamPlainAddresses) > 0 {
+		if d.UpstreamType == DNSUpstreamTypePlain {
+			for _, addr := range d.UpstreamPlainAddresses {
+				upstreamResolvers.Append(addr.String())
+			}
+		} else {
+			node.Appendf("Upstream plain addresses: ignored because upstream type is not plain")
+			for _, provider := range d.Providers {
+				upstreamResolvers.Append(provider)
+			}
+		}
+	} else {
+		for _, provider := range d.Providers {
+			upstreamResolvers.Append(provider)
+		}
 	}
 
 	node.Appendf("Caching: %s", gosettings.BoolToYesNo(d.Caching))
@@ -217,15 +245,42 @@ func (d *DNS) read(r *reader.Reader) (err error) {
 		return err
 	}
 
-	d.ServerAddress, err = r.NetipAddr("DNS_ADDRESS", reader.RetroKeys("DNS_PLAINTEXT_ADDRESS"))
-	if err != nil {
-		return err
-	}
-
-	d.KeepNameserver, err = r.BoolPtr("DNS_KEEP_NAMESERVER")
+	err = d.readUpstreamPlainAddresses(r)
 	if err != nil {
 		return err
 	}
 
 	return nil
 }
+
+func (d *DNS) readUpstreamPlainAddresses(r *reader.Reader) (err error) {
+	// If DNS_UPSTREAM_PLAIN_ADDRESSES is set, the user must also set DNS_UPSTREAM_RESOLVER_TYPE=plain
+	// for these to be used. This is an added safety measure to reduce misunderstandings, and
+	// reduce odd settings overrides.
+	d.UpstreamPlainAddresses, err = r.CSVNetipAddrPorts("DNS_UPSTREAM_PLAIN_ADDRESSES")
+	if err != nil {
+		return err
+	}
+
+	// Retro-compatibility - remove in v4
+	// If DNS_ADDRESS is set to a non-localhost address, append it to the other
+	// upstream plain addresses, assuming port 53, and force the upstream type to plain
+	// to maintain retro-compatibility behavior.
+	serverAddress, err := r.NetipAddr("DNS_ADDRESS",
+		reader.RetroKeys("DNS_PLAINTEXT_ADDRESS"),
+		reader.IsRetro("DNS_UPSTREAM_PLAIN_ADDRESSES"))
+	if err != nil {
+		return err
+	} else if !serverAddress.IsValid() {
+		return nil
+	}
+	isLocalhost := serverAddress.Compare(netip.AddrFrom4([4]byte{127, 0, 0, 1})) == 0
+	if isLocalhost {
+		return nil
+	}
+	const defaultPlainPort = 53
+	addrPort := netip.AddrPortFrom(serverAddress, defaultPlainPort)
+	d.UpstreamPlainAddresses = append(d.UpstreamPlainAddresses, addrPort)
+	d.UpstreamType = DNSUpstreamTypePlain
+	return nil
+}

internal/configuration/settings/dns_test.go

@@ -0,0 +1,26 @@
+package settings
+
+import (
+	"testing"
+
+	"github.com/qdm12/dns/v2/pkg/provider"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_defaultDNSProviders(t *testing.T) {
+	t.Parallel()
+
+	names := defaultDNSProviders()
+
+	found := false
+	providers := provider.NewProviders()
+	for _, name := range names {
+		provider, err := providers.Get(name)
+		require.NoError(t, err)
+		if len(provider.Plain.IPv4) > 0 {
+			found = true
+			break
+		}
+	}
+	require.True(t, found, "no default DNS provider has a plaintext IPv4 address")
+}

internal/configuration/settings/dnsblacklist.go

@@ -1,7 +1,6 @@
 package settings
 
 import (
-	"errors"
 	"fmt"
 	"net/http"
 	"net/netip"
@@ -17,7 +16,6 @@ import (
 type DNSBlacklist struct {
 	BlockMalicious       *bool
 	BlockAds             *bool
-	BlockSurveillance    *bool
 	AllowedHosts         []string
 	AddBlockedHosts      []string
 	AddBlockedIPs        []netip.Addr
@@ -32,27 +30,20 @@ type DNSBlacklist struct {
 func (b *DNSBlacklist) setDefaults() {
 	b.BlockMalicious = gosettings.DefaultPointer(b.BlockMalicious, true)
 	b.BlockAds = gosettings.DefaultPointer(b.BlockAds, false)
-	b.BlockSurveillance = gosettings.DefaultPointer(b.BlockSurveillance, true)
 }
 
 var hostRegex = regexp.MustCompile(`^([a-zA-Z0-9]|[a-zA-Z0-9_][a-zA-Z0-9\-_]{0,61}[a-zA-Z0-9_])(\.([a-zA-Z0-9]|[a-zA-Z0-9_][a-zA-Z0-9\-_]{0,61}[a-zA-Z0-9]))*$`) //nolint:lll
 
-var (
-	ErrAllowedHostNotValid                   = errors.New("allowed host is not valid")
-	ErrBlockedHostNotValid                   = errors.New("blocked host is not valid")
-	ErrRebindingProtectionExemptHostNotValid = errors.New("rebinding protection exempt host is not valid")
-)
-
 func (b DNSBlacklist) validate() (err error) {
 	for _, host := range b.AllowedHosts {
 		if !hostRegex.MatchString(host) {
-			return fmt.Errorf("%w: %s", ErrAllowedHostNotValid, host)
+			return fmt.Errorf("allowed host is not valid: %s", host)
 		}
 	}
 
 	for _, host := range b.AddBlockedHosts {
 		if !hostRegex.MatchString(host) {
-			return fmt.Errorf("%w: %s", ErrBlockedHostNotValid, host)
+			return fmt.Errorf("blocked host is not valid: %s", host)
 		}
 	}
 
@@ -61,7 +52,7 @@ func (b DNSBlacklist) validate() (err error) {
 			host = host[2:]
 		}
 		if !hostRegex.MatchString(host) {
-			return fmt.Errorf("%w: %s", ErrRebindingProtectionExemptHostNotValid, host)
+			return fmt.Errorf("rebinding protection exempt host is not valid: %s", host)
 		}
 	}
 
@@ -72,7 +63,6 @@ func (b DNSBlacklist) copy() (copied DNSBlacklist) {
 	return DNSBlacklist{
 		BlockMalicious:                     gosettings.CopyPointer(b.BlockMalicious),
 		BlockAds:                           gosettings.CopyPointer(b.BlockAds),
-		BlockSurveillance:                  gosettings.CopyPointer(b.BlockSurveillance),
 		AllowedHosts:                       gosettings.CopySlice(b.AllowedHosts),
 		AddBlockedHosts:                    gosettings.CopySlice(b.AddBlockedHosts),
 		AddBlockedIPs:                      gosettings.CopySlice(b.AddBlockedIPs),
@@ -84,7 +74,6 @@ func (b DNSBlacklist) copy() (copied DNSBlacklist) {
 func (b *DNSBlacklist) overrideWith(other DNSBlacklist) {
 	b.BlockMalicious = gosettings.OverrideWithPointer(b.BlockMalicious, other.BlockMalicious)
 	b.BlockAds = gosettings.OverrideWithPointer(b.BlockAds, other.BlockAds)
-	b.BlockSurveillance = gosettings.OverrideWithPointer(b.BlockSurveillance, other.BlockSurveillance)
 	b.AllowedHosts = gosettings.OverrideWithSlice(b.AllowedHosts, other.AllowedHosts)
 	b.AddBlockedHosts = gosettings.OverrideWithSlice(b.AddBlockedHosts, other.AddBlockedHosts)
 	b.AddBlockedIPs = gosettings.OverrideWithSlice(b.AddBlockedIPs, other.AddBlockedIPs)
@@ -100,7 +89,6 @@ func (b DNSBlacklist) ToBlockBuilderSettings(client *http.Client) (
 		Client:               client,
 		BlockMalicious:       b.BlockMalicious,
 		BlockAds:             b.BlockAds,
-		BlockSurveillance:    b.BlockSurveillance,
 		AllowedHosts:         b.AllowedHosts,
 		AddBlockedHosts:      b.AddBlockedHosts,
 		AddBlockedIPs:        b.AddBlockedIPs,
@@ -117,7 +105,6 @@ func (b DNSBlacklist) toLinesNode() (node *gotree.Node) {
 
 	node.Appendf("Block malicious: %s", gosettings.BoolToYesNo(b.BlockMalicious))
 	node.Appendf("Block ads: %s", gosettings.BoolToYesNo(b.BlockAds))
-	node.Appendf("Block surveillance: %s", gosettings.BoolToYesNo(b.BlockSurveillance))
 
 	if len(b.AllowedHosts) > 0 {
 		allowedHostsNode := node.Append("Allowed hosts:")
@@ -163,12 +150,6 @@ func (b *DNSBlacklist) read(r *reader.Reader) (err error) {
 		return err
 	}
 
-	b.BlockSurveillance, err = r.BoolPtr("BLOCK_SURVEILLANCE",
-		reader.RetroKeys("BLOCK_NSA"))
-	if err != nil {
-		return err
-	}
-
 	b.BlockAds, err = r.BoolPtr("BLOCK_ADS")
 	if err != nil {
 		return err
@@ -209,8 +190,6 @@ func readDNSBlockedIPs(r *reader.Reader) (ips []netip.Addr,
 	return ips, ipPrefixes, nil
 }
 
-var ErrPrivateAddressNotValid = errors.New("private address is not a valid IP or CIDR range")
-
 func readDNSPrivateAddresses(r *reader.Reader) (ips []netip.Addr,
 	ipPrefixes []netip.Prefix, err error,
 ) {
@@ -236,8 +215,9 @@ func readDNSPrivateAddresses(r *reader.Reader) (ips []netip.Addr,
 		}
 
 		return nil, nil, fmt.Errorf(
-			"environment variable DOT_PRIVATE_ADDRESS: %w: %s",
-			ErrPrivateAddressNotValid, privateAddress)
+			"environment variable DOT_PRIVATE_ADDRESS: "+
+				"private address is not a valid IP or CIDR range: %s",
+			privateAddress)
 	}
 
 	return ips, ipPrefixes, nil

internal/configuration/settings/errors.go

@@ -1,58 +0,0 @@
-package settings
-
-import "errors"
-
-var (
-	ErrValueUnknown                    = errors.New("value is unknown")
-	ErrCityNotValid                    = errors.New("the city specified is not valid")
-	ErrControlServerPrivilegedPort     = errors.New("cannot use privileged port without running as root")
-	ErrCategoryNotValid                = errors.New("the category specified is not valid")
-	ErrCountryNotValid                 = errors.New("the country specified is not valid")
-	ErrFilepathMissing                 = errors.New("filepath is missing")
-	ErrFirewallZeroPort                = errors.New("cannot have a zero port")
-	ErrFirewallPublicOutboundSubnet    = errors.New("outbound subnet has an unspecified address")
-	ErrHostnameNotValid                = errors.New("the hostname specified is not valid")
-	ErrISPNotValid                     = errors.New("the ISP specified is not valid")
-	ErrMinRatioNotValid                = errors.New("minimum ratio is not valid")
-	ErrMissingValue                    = errors.New("missing value")
-	ErrNameNotValid                    = errors.New("the server name specified is not valid")
-	ErrOpenVPNClientKeyMissing         = errors.New("client key is missing")
-	ErrOpenVPNCustomPortNotAllowed     = errors.New("custom endpoint port is not allowed")
-	ErrOpenVPNEncryptionPresetNotValid = errors.New("PIA encryption preset is not valid")
-	ErrOpenVPNInterfaceNotValid        = errors.New("interface name is not valid")
-	ErrOpenVPNKeyPassphraseIsEmpty     = errors.New("key passphrase is empty")
-	ErrOpenVPNMSSFixIsTooHigh          = errors.New("mssfix option value is too high")
-	ErrOpenVPNPasswordIsEmpty          = errors.New("password is empty")
-	ErrOpenVPNTCPNotSupported          = errors.New("TCP protocol is not supported")
-	ErrOpenVPNUserIsEmpty              = errors.New("user is empty")
-	ErrOpenVPNVerbosityIsOutOfBounds   = errors.New("verbosity value is out of bounds")
-	ErrOpenVPNVersionIsNotValid        = errors.New("version is not valid")
-	ErrPortForwardingEnabled           = errors.New("port forwarding cannot be enabled")
-	ErrPortForwardingUserEmpty         = errors.New("port forwarding username is empty")
-	ErrPortForwardingPasswordEmpty     = errors.New("port forwarding password is empty")
-	ErrRegionNotValid                  = errors.New("the region specified is not valid")
-	ErrServerAddressNotValid           = errors.New("server listening address is not valid")
-	ErrSystemPGIDNotValid              = errors.New("process group id is not valid")
-	ErrSystemPUIDNotValid              = errors.New("process user id is not valid")
-	ErrSystemTimezoneNotValid          = errors.New("timezone is not valid")
-	ErrUpdaterPeriodTooSmall           = errors.New("VPN server data updater period is too small")
-	ErrUpdaterProtonPasswordMissing    = errors.New("proton password is missing")
-	ErrUpdaterProtonEmailMissing       = errors.New("proton email is missing")
-	ErrVPNProviderNameNotValid         = errors.New("VPN provider name is not valid")
-	ErrVPNTypeNotValid                 = errors.New("VPN type is not valid")
-	ErrWireguardAllowedIPNotSet        = errors.New("allowed IP is not set")
-	ErrWireguardAllowedIPsNotSet       = errors.New("allowed IPs is not set")
-	ErrWireguardEndpointIPNotSet       = errors.New("endpoint IP is not set")
-	ErrWireguardEndpointPortNotAllowed = errors.New("endpoint port is not allowed")
-	ErrWireguardEndpointPortNotSet     = errors.New("endpoint port is not set")
-	ErrWireguardEndpointPortSet        = errors.New("endpoint port is set")
-	ErrWireguardInterfaceAddressNotSet = errors.New("interface address is not set")
-	ErrWireguardInterfaceAddressIPv6   = errors.New("interface address is IPv6 but IPv6 is not supported")
-	ErrWireguardInterfaceNotValid      = errors.New("interface name is not valid")
-	ErrWireguardPreSharedKeyNotSet     = errors.New("pre-shared key is not set")
-	ErrWireguardPrivateKeyNotSet       = errors.New("private key is not set")
-	ErrWireguardPublicKeyNotSet        = errors.New("public key is not set")
-	ErrWireguardPublicKeyNotValid      = errors.New("public key is not valid")
-	ErrWireguardKeepAliveNegative      = errors.New("persistent keep alive interval is negative")
-	ErrWireguardImplementationNotValid = errors.New("implementation is not valid")
-)

internal/configuration/settings/firewall.go

@@ -1,6 +1,7 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"net/netip"
 
@@ -16,22 +17,22 @@ type Firewall struct {
 	InputPorts      []uint16
 	OutboundSubnets []netip.Prefix
 	Enabled         *bool
-	Debug           *bool
 	Implementation  string
+	Iptables        Iptables
 }
 
 func (f Firewall) validate() (err error) {
 	if hasZeroPort(f.VPNInputPorts) {
-		return fmt.Errorf("VPN input ports: %w", ErrFirewallZeroPort)
+		return errors.New("VPN input ports: cannot have a zero port")
 	}
 
 	if hasZeroPort(f.InputPorts) {
-		return fmt.Errorf("input ports: %w", ErrFirewallZeroPort)
+		return errors.New("input ports: cannot have a zero port")
 	}
 
 	for _, subnet := range f.OutboundSubnets {
 		if subnet.Addr().IsUnspecified() {
-			return fmt.Errorf("%w: %s", ErrFirewallPublicOutboundSubnet, subnet)
+			return fmt.Errorf("outbound subnet has an unspecified address: %s", subnet)
 		}
 	}
 
@@ -40,6 +41,11 @@ func (f Firewall) validate() (err error) {
 		return fmt.Errorf("firewall implementation: %w", err)
 	}
 
+	err = f.Iptables.validate()
+	if err != nil {
+		return fmt.Errorf("iptables settings: %w", err)
+	}
+
 	return nil
 }
 
@@ -58,8 +64,8 @@ func (f *Firewall) copy() (copied Firewall) {
 		InputPorts:      gosettings.CopySlice(f.InputPorts),
 		OutboundSubnets: gosettings.CopySlice(f.OutboundSubnets),
 		Enabled:         gosettings.CopyPointer(f.Enabled),
-		Debug:           gosettings.CopyPointer(f.Debug),
 		Implementation:  f.Implementation,
+		Iptables:        f.Iptables.copy(),
 	}
 }
 
@@ -71,14 +77,14 @@ func (f *Firewall) overrideWith(other Firewall) {
 	f.InputPorts = gosettings.OverrideWithSlice(f.InputPorts, other.InputPorts)
 	f.OutboundSubnets = gosettings.OverrideWithSlice(f.OutboundSubnets, other.OutboundSubnets)
 	f.Enabled = gosettings.OverrideWithPointer(f.Enabled, other.Enabled)
-	f.Debug = gosettings.OverrideWithPointer(f.Debug, other.Debug)
 	f.Implementation = gosettings.OverrideWithComparable(f.Implementation, other.Implementation)
+	f.Iptables.overrideWith(other.Iptables)
 }
 
-func (f *Firewall) setDefaults() {
+func (f *Firewall) setDefaults(globalLogLevel string) {
 	f.Enabled = gosettings.DefaultPointer(f.Enabled, true)
-	f.Debug = gosettings.DefaultPointer(f.Debug, false)
 	f.Implementation = gosettings.DefaultComparable(f.Implementation, "iptables")
+	f.Iptables.setDefaults(globalLogLevel)
 }
 
 func (f Firewall) String() string {
@@ -94,10 +100,7 @@ func (f Firewall) toLinesNode() (node *gotree.Node) {
 	}
 
 	node.Appendf("Implementation: %s", f.Implementation)
-
-	if *f.Debug {
-		node.Appendf("Debug mode: on")
-	}
+	node.AppendNode(f.Iptables.toLinesNode())
 
 	if len(f.VPNInputPorts) > 0 {
 		vpnInputPortsNode := node.Appendf("VPN input ports:")
@@ -145,9 +148,9 @@ func (f *Firewall) read(r *reader.Reader) (err error) {
 		return err
 	}
 
-	f.Debug, err = r.BoolPtr("FIREWALL_DEBUG")
+	err = f.Iptables.read(r)
 	if err != nil {
-		return err
+		return fmt.Errorf("reading iptables settings: %w", err)
 	}
 
 	f.Implementation = r.String("FIREWALL_IMPLEMENTATION")

internal/configuration/settings/firewall_test.go

@@ -4,6 +4,7 @@ import (
 	"net/netip"
 	"testing"
 
+	"github.com/qdm12/log"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -12,22 +13,21 @@ func Test_Firewall_validate(t *testing.T) {
 
 	testCases := map[string]struct {
 		firewall   Firewall
-		errWrapped error
 		errMessage string
 	}{
-		"empty": {},
+		"empty": {
+			errMessage: "iptables settings: log level: level is not recognized: ",
+		},
 		"zero_vpn_input_port": {
 			firewall: Firewall{
 				VPNInputPorts: []uint16{0},
 			},
-			errWrapped: ErrFirewallZeroPort,
 			errMessage: "VPN input ports: cannot have a zero port",
 		},
 		"zero_input_port": {
 			firewall: Firewall{
 				InputPorts: []uint16{0},
 			},
-			errWrapped: ErrFirewallZeroPort,
 			errMessage: "input ports: cannot have a zero port",
 		},
 		"unspecified_outbound_subnet": {
@@ -36,11 +36,11 @@ func Test_Firewall_validate(t *testing.T) {
 					netip.MustParsePrefix("0.0.0.0/0"),
 				},
 			},
-			errWrapped: ErrFirewallPublicOutboundSubnet,
 			errMessage: "outbound subnet has an unspecified address: 0.0.0.0/0",
 		},
 		"public_outbound_subnet": {
 			firewall: Firewall{
+				Iptables: Iptables{LogLevel: log.LevelInfo.String()},
 				OutboundSubnets: []netip.Prefix{
 					netip.MustParsePrefix("1.2.3.4/32"),
 				},
@@ -48,6 +48,7 @@ func Test_Firewall_validate(t *testing.T) {
 		},
 		"valid_settings": {
 			firewall: Firewall{
+				Iptables:      Iptables{LogLevel: log.LevelInfo.String()},
 				VPNInputPorts: []uint16{100, 101},
 				InputPorts:    []uint16{200, 201},
 				OutboundSubnets: []netip.Prefix{
@@ -64,9 +65,10 @@ func Test_Firewall_validate(t *testing.T) {
 
 			err := testCase.firewall.validate()
 
-			assert.ErrorIs(t, err, testCase.errWrapped)
-			if testCase.errWrapped != nil {
+			if testCase.errMessage != "" {
 				assert.EqualError(t, err, testCase.errMessage)
+			} else {
+				assert.NoError(t, err)
 			}
 		})
 	}

internal/configuration/settings/health.go

@@ -38,12 +38,6 @@ type Health struct {
 	RestartVPN *bool
 }
 
-var (
-	ErrICMPTargetIPNotValid       = errors.New("ICMP target IP address is not valid")
-	ErrICMPTargetIPsNotCompatible = errors.New("ICMP target IP addresses are not compatible")
-	ErrSmallCheckTypeNotValid     = errors.New("small check type is not valid")
-)
-
 func (h Health) Validate() (err error) {
 	err = validate.ListeningAddress(h.ServerAddress, os.Getuid())
 	if err != nil {
@@ -53,16 +47,16 @@ func (h Health) Validate() (err error) {
 	for _, ip := range h.ICMPTargetIPs {
 		switch {
 		case !ip.IsValid():
-			return fmt.Errorf("%w: %s", ErrICMPTargetIPNotValid, ip)
+			return fmt.Errorf("ICMP target IP address is not valid: %s", ip)
 		case ip.IsUnspecified() && len(h.ICMPTargetIPs) > 1:
-			return fmt.Errorf("%w: only a single IP address must be set if it is to be unspecified",
-				ErrICMPTargetIPsNotCompatible)
+			return errors.New("ICMP target IP addresses are not compatible: " +
+				"only a single IP address must be set if it is to be unspecified")
 		}
 	}
 
 	err = validate.IsOneOf(h.SmallCheckType, "icmp", "dns")
 	if err != nil {
-		return fmt.Errorf("%w: %s", ErrSmallCheckTypeNotValid, err)
+		return fmt.Errorf("small check type is not valid: %w", err)
 	}
 
 	return nil

internal/configuration/settings/helpers_test.go

@@ -1,6 +1,6 @@
 package settings
 
-import gomock "github.com/golang/mock/gomock"
+import gomock "go.uber.org/mock/gomock"
 
 type sourceKeyValue struct {
 	key   string

internal/configuration/settings/httpproxy.go

@@ -48,7 +48,7 @@ func (h HTTPProxy) validate() (err error) {
 	// Do not validate user and password
 	err = validate.ListeningAddress(h.ListeningAddress, os.Getuid())
 	if err != nil {
-		return fmt.Errorf("%w: %s", ErrServerAddressNotValid, h.ListeningAddress)
+		return fmt.Errorf("server listening address is not valid: %w", err)
 	}
 
 	return nil
@@ -176,7 +176,6 @@ func readHTTProxyLog(r *reader.Reader) (enabled *bool, err error) {
 	case "disabled", "no", "off":
 		return ptrTo(false), nil
 	default:
-		return nil, fmt.Errorf("HTTP retro-compatible proxy log setting: %w: %s",
-			ErrValueUnknown, value)
+		return nil, fmt.Errorf("HTTP retro-compatible proxy log setting: value is unknown: %s", value)
 	}
 }

internal/configuration/settings/iptables.go

@@ -0,0 +1,67 @@
+package settings
+
+import (
+	"fmt"
+
+	"github.com/qdm12/gosettings"
+	"github.com/qdm12/gosettings/reader"
+	"github.com/qdm12/gotree"
+	"github.com/qdm12/log"
+)
+
+// Iptables contains settings to customize iptables.
+type Iptables struct {
+	LogLevel string
+}
+
+func (i Iptables) validate() (err error) {
+	_, err = log.ParseLevel(i.LogLevel)
+	if err != nil {
+		return fmt.Errorf("log level: %w", err)
+	}
+
+	return nil
+}
+
+func (i *Iptables) copy() (copied Iptables) {
+	return Iptables{
+		LogLevel: i.LogLevel,
+	}
+}
+
+func (i *Iptables) overrideWith(other Iptables) {
+	i.LogLevel = gosettings.OverrideWithComparable(i.LogLevel, other.LogLevel)
+}
+
+func (i *Iptables) setDefaults(globalLogLevel string) {
+	defaultLevel := globalLogLevel
+	if defaultLevel == log.LevelDebug.String() {
+		// Given iptables debug logger is quite verbose, we only turn it to debug level
+		// if it is explicitly asked to be at debug level; even if the global logger is
+		// at the debug level, we keep iptables at info level by default.
+		defaultLevel = log.LevelInfo.String()
+	}
+	i.LogLevel = gosettings.DefaultComparable(i.LogLevel, defaultLevel)
+}
+
+func (i Iptables) String() string {
+	return i.toLinesNode().String()
+}
+
+func (i Iptables) toLinesNode() (node *gotree.Node) {
+	node = gotree.New("Iptables settings:")
+	node.Appendf("Log level: %s", i.LogLevel)
+	return node
+}
+
+func (i *Iptables) read(r *reader.Reader) (err error) {
+	debugMode, err := r.BoolPtr("FIREWALL_DEBUG", reader.IsRetro("FIREWALL_IPTABLES_LOG_LEVEL"))
+	if err != nil {
+		return err
+	}
+	if debugMode != nil && *debugMode {
+		i.LogLevel = log.LevelDebug.String()
+	}
+	i.LogLevel = r.String("FIREWALL_IPTABLES_LOG_LEVEL")
+	return nil
+}

internal/configuration/settings/ipv6.go

@@ -0,0 +1,58 @@
+package settings
+
+import (
+	"net/netip"
+
+	"github.com/qdm12/gosettings"
+	"github.com/qdm12/gosettings/reader"
+	"github.com/qdm12/gotree"
+)
+
+// IPv6 contains settings regarding IPv6 configuration.
+type IPv6 struct {
+	// CheckAddresses are the TCP ip:port addresses to dial to check if
+	// IPv6 is supported, in case a default IPv6 route is found.
+	// It defaults to google and cloudflare IPv6 anycast addresses
+	// [2001:4860:4860::8888]:53,[2606:4700:4700::1111]:53
+	CheckAddresses []netip.AddrPort
+}
+
+func (i IPv6) validate() (err error) {
+	return nil
+}
+
+func (i *IPv6) copy() (copied IPv6) {
+	return IPv6{
+		CheckAddresses: gosettings.CopySlice(i.CheckAddresses),
+	}
+}
+
+func (i *IPv6) overrideWith(other IPv6) {
+	i.CheckAddresses = gosettings.OverrideWithSlice(i.CheckAddresses, other.CheckAddresses)
+}
+
+func (i *IPv6) setDefaults() {
+	defaultCheckAddresses := []netip.AddrPort{
+		netip.MustParseAddrPort("[2001:4860:4860::8888]:53"),
+		netip.MustParseAddrPort("[2606:4700:4700::1111]:53"),
+	}
+	i.CheckAddresses = gosettings.DefaultSlice(i.CheckAddresses, defaultCheckAddresses)
+}
+
+func (i IPv6) String() string {
+	return i.toLinesNode().String()
+}
+
+func (i IPv6) toLinesNode() (node *gotree.Node) {
+	node = gotree.New("IPv6 settings:")
+	addrsNode := node.Appendf("Check addresses:")
+	for _, addr := range i.CheckAddresses {
+		addrsNode.Append(addr.String())
+	}
+	return node
+}
+
+func (i *IPv6) read(r *reader.Reader) (err error) {
+	i.CheckAddresses, err = r.CSVNetipAddrPorts("IPV6_CHECK_ADDRESSES")
+	return err
+}

internal/configuration/settings/mocks_reader_test.go

@@ -1,5 +1,10 @@
 // Code generated by MockGen. DO NOT EDIT.
 // Source: github.com/qdm12/gosettings/reader (interfaces: Source)
+//
+// Generated by this command:
+//
+//	mockgen -destination=mocks_reader_test.go -package=settings github.com/qdm12/gosettings/reader Source
+//
 
 // Package settings is a generated GoMock package.
 package settings
@@ -7,13 +12,14 @@ package settings
 import (
 	reflect "reflect"
 
-	gomock "github.com/golang/mock/gomock"
+	gomock "go.uber.org/mock/gomock"
 )
 
 // MockSource is a mock of Source interface.
 type MockSource struct {
 	ctrl     *gomock.Controller
 	recorder *MockSourceMockRecorder
+	isgomock struct{}
 }
 
 // MockSourceMockRecorder is the mock recorder for MockSource.
@@ -34,32 +40,32 @@ func (m *MockSource) EXPECT() *MockSourceMockRecorder {
 }
 
 // Get mocks base method.
-func (m *MockSource) Get(arg0 string) (string, bool) {
+func (m *MockSource) Get(key string) (string, bool) {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "Get", arg0)
+	ret := m.ctrl.Call(m, "Get", key)
 	ret0, _ := ret[0].(string)
 	ret1, _ := ret[1].(bool)
 	return ret0, ret1
 }
 
 // Get indicates an expected call of Get.
-func (mr *MockSourceMockRecorder) Get(arg0 interface{}) *gomock.Call {
+func (mr *MockSourceMockRecorder) Get(key any) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Get", reflect.TypeOf((*MockSource)(nil).Get), arg0)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Get", reflect.TypeOf((*MockSource)(nil).Get), key)
 }
 
 // KeyTransform mocks base method.
-func (m *MockSource) KeyTransform(arg0 string) string {
+func (m *MockSource) KeyTransform(key string) string {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "KeyTransform", arg0)
+	ret := m.ctrl.Call(m, "KeyTransform", key)
 	ret0, _ := ret[0].(string)
 	return ret0
 }
 
 // KeyTransform indicates an expected call of KeyTransform.
-func (mr *MockSourceMockRecorder) KeyTransform(arg0 interface{}) *gomock.Call {
+func (mr *MockSourceMockRecorder) KeyTransform(key any) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "KeyTransform", reflect.TypeOf((*MockSource)(nil).KeyTransform), arg0)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "KeyTransform", reflect.TypeOf((*MockSource)(nil).KeyTransform), key)
 }
 
 // String mocks base method.

internal/configuration/settings/mocks_test.go

@@ -1,5 +1,10 @@
 // Code generated by MockGen. DO NOT EDIT.
 // Source: github.com/qdm12/gluetun/internal/configuration/settings (interfaces: Warner)
+//
+// Generated by this command:
+//
+//	mockgen -destination=mocks_test.go -package=settings . Warner
+//
 
 // Package settings is a generated GoMock package.
 package settings
@@ -7,13 +12,14 @@ package settings
 import (
 	reflect "reflect"
 
-	gomock "github.com/golang/mock/gomock"
+	gomock "go.uber.org/mock/gomock"
 )
 
 // MockWarner is a mock of Warner interface.
 type MockWarner struct {
 	ctrl     *gomock.Controller
 	recorder *MockWarnerMockRecorder
+	isgomock struct{}
 }
 
 // MockWarnerMockRecorder is the mock recorder for MockWarner.
@@ -34,13 +40,13 @@ func (m *MockWarner) EXPECT() *MockWarnerMockRecorder {
 }
 
 // Warn mocks base method.
-func (m *MockWarner) Warn(arg0 string) {
+func (m *MockWarner) Warn(message string) {
 	m.ctrl.T.Helper()
-	m.ctrl.Call(m, "Warn", arg0)
+	m.ctrl.Call(m, "Warn", message)
 }
 
 // Warn indicates an expected call of Warn.
-func (mr *MockWarnerMockRecorder) Warn(arg0 interface{}) *gomock.Call {
+func (mr *MockWarnerMockRecorder) Warn(message any) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Warn", reflect.TypeOf((*MockWarner)(nil).Warn), arg0)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Warn", reflect.TypeOf((*MockWarner)(nil).Warn), message)
 }

internal/configuration/settings/openvpn.go

@@ -2,6 +2,7 @@ package settings
 
 import (
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"regexp"
 	"strings"
@@ -92,7 +93,7 @@ func (o OpenVPN) validate(vpnProvider string) (err error) {
 	// Validate version
 	validVersions := []string{openvpn.Openvpn25, openvpn.Openvpn26}
 	if err = validate.IsOneOf(o.Version, validVersions...); err != nil {
-		return fmt.Errorf("%w: %w", ErrOpenVPNVersionIsNotValid, err)
+		return fmt.Errorf("version is not valid: %w", err)
 	}
 
 	isCustom := vpnProvider == providers.Custom
@@ -101,14 +102,14 @@ func (o OpenVPN) validate(vpnProvider string) (err error) {
 		vpnProvider != providers.VPNSecure
 
 	if isUserRequired && *o.User == "" {
-		return fmt.Errorf("%w", ErrOpenVPNUserIsEmpty)
+		return errors.New("user is empty")
 	}
 
 	passwordRequired := isUserRequired &&
 		(vpnProvider != providers.Ivpn || !ivpnAccountID.MatchString(*o.User))
 
 	if passwordRequired && *o.Password == "" {
-		return fmt.Errorf("%w", ErrOpenVPNPasswordIsEmpty)
+		return errors.New("password is empty")
 	}
 
 	err = validateOpenVPNConfigFilepath(isCustom, *o.ConfFile)
@@ -132,23 +133,20 @@ func (o OpenVPN) validate(vpnProvider string) (err error) {
 	}
 
 	if *o.EncryptedKey != "" && *o.KeyPassphrase == "" {
-		return fmt.Errorf("%w", ErrOpenVPNKeyPassphraseIsEmpty)
+		return errors.New("key passphrase is empty")
 	}
 
 	const maxMSSFix = 10000
 	if *o.MSSFix > maxMSSFix {
-		return fmt.Errorf("%w: %d is over the maximum value of %d",
-			ErrOpenVPNMSSFixIsTooHigh, *o.MSSFix, maxMSSFix)
+		return fmt.Errorf("mssfix option value is too high: %d is over the maximum value of %d", *o.MSSFix, maxMSSFix)
 	}
 
 	if !regexpInterfaceName.MatchString(o.Interface) {
-		return fmt.Errorf("%w: '%s' does not match regex '%s'",
-			ErrOpenVPNInterfaceNotValid, o.Interface, regexpInterfaceName)
+		return fmt.Errorf("interface name is not valid: '%s' does not match regex '%s'", o.Interface, regexpInterfaceName)
 	}
 
 	if *o.Verbosity < 0 || *o.Verbosity > 6 {
-		return fmt.Errorf("%w: %d can only be between 0 and 5",
-			ErrOpenVPNVerbosityIsOutOfBounds, o.Verbosity)
+		return fmt.Errorf("verbosity value is out of bounds: %d can only be between 0 and 5", o.Verbosity)
 	}
 
 	return nil
@@ -162,7 +160,7 @@ func validateOpenVPNConfigFilepath(isCustom bool,
 	}
 
 	if confFile == "" {
-		return fmt.Errorf("%w", ErrFilepathMissing)
+		return errors.New("filepath is missing")
 	}
 
 	err = validate.FileExists(confFile)
@@ -189,7 +187,7 @@ func validateOpenVPNClientCertificate(vpnProvider,
 		providers.VPNSecure,
 		providers.VPNUnlimited:
 		if clientCert == "" {
-			return fmt.Errorf("%w", ErrMissingValue)
+			return errors.New("missing value")
 		}
 	}
 
@@ -211,7 +209,7 @@ func validateOpenVPNClientKey(vpnProvider, clientKey string) (err error) {
 		providers.Cyberghost,
 		providers.VPNUnlimited:
 		if clientKey == "" {
-			return fmt.Errorf("%w", ErrMissingValue)
+			return errors.New("missing value")
 		}
 	}
 
@@ -230,7 +228,7 @@ func validateOpenVPNEncryptedKey(vpnProvider,
 	encryptedPrivateKey string,
 ) (err error) {
 	if vpnProvider == providers.VPNSecure && encryptedPrivateKey == "" {
-		return fmt.Errorf("%w", ErrMissingValue)
+		return errors.New("missing value")
 	}
 
 	if encryptedPrivateKey == "" {

internal/configuration/settings/openvpnselection.go

@@ -59,12 +59,9 @@ func (o OpenVPNSelection) validate(vpnProvider string) (err error) {
 	if o.Protocol == constants.TCP && helpers.IsOneOf(vpnProvider,
 		providers.Giganews,
 		providers.Ipvanish,
-		providers.Perfectprivacy,
-		providers.Privado,
 		providers.Vyprvpn,
 	) {
-		return fmt.Errorf("%w: for VPN service provider %s",
-			ErrOpenVPNTCPNotSupported, vpnProvider)
+		return fmt.Errorf("TCP protocol is not supported: for VPN service provider %s", vpnProvider)
 	}
 
 	// Validate CustomPort
@@ -75,12 +72,11 @@ func (o OpenVPNSelection) validate(vpnProvider string) (err error) {
 			providers.Privatevpn, providers.Torguard:
 		// no custom port allowed
 		case providers.Expressvpn, providers.Fastestvpn,
-			providers.Giganews, providers.Ipvanish, providers.Nordvpn,
-			providers.Privado, providers.Purevpn,
+			providers.Giganews, providers.Ipvanish,
+			providers.Nordvpn, providers.Purevpn,
 			providers.Surfshark, providers.VPNSecure,
 			providers.VPNUnlimited, providers.Vyprvpn:
-			return fmt.Errorf("%w: for VPN service provider %s",
-				ErrOpenVPNCustomPortNotAllowed, vpnProvider)
+			return fmt.Errorf("custom endpoint port is not allowed: for VPN service provider %s", vpnProvider)
 		default:
 			var allowedTCP, allowedUDP []uint16
 			switch vpnProvider {
@@ -96,11 +92,11 @@ func (o OpenVPNSelection) validate(vpnProvider string) (err error) {
 			case providers.Mullvad:
 				allowedTCP = []uint16{80, 443, 1401}
 				allowedUDP = []uint16{53, 1194, 1195, 1196, 1197, 1300, 1301, 1302, 1303, 1400}
-			case providers.Perfectprivacy:
-				allowedTCP = []uint16{44, 443, 4433}
-				allowedUDP = []uint16{44, 443, 4433}
+			case providers.Privado:
+				allowedTCP = []uint16{443, 1194, 8080, 8443}
+				allowedUDP = []uint16{443, 1194, 8080, 8443}
 			case providers.PrivateInternetAccess:
-				allowedTCP = []uint16{80, 110, 443}
+				allowedTCP = []uint16{80, 110, 443, 501, 502, 8443}
 				allowedUDP = []uint16{53, 1194, 1197, 1198, 8080, 9201}
 			case providers.Protonvpn:
 				allowedTCP = []uint16{443, 5995, 8443}
@@ -121,8 +117,7 @@ func (o OpenVPNSelection) validate(vpnProvider string) (err error) {
 			}
 			err = validate.IsOneOf(*o.CustomPort, allowedPorts...)
 			if err != nil {
-				return fmt.Errorf("%w: for VPN service provider %s: %w",
-					ErrOpenVPNCustomPortNotAllowed, vpnProvider, err)
+				return fmt.Errorf("custom endpoint port is not allowed: for VPN service provider %s: %w", vpnProvider, err)
 			}
 		}
 	}
@@ -130,12 +125,11 @@ func (o OpenVPNSelection) validate(vpnProvider string) (err error) {
 	// Validate EncPreset
 	if vpnProvider == providers.PrivateInternetAccess {
 		validEncryptionPresets := []string{
-			presets.None,
 			presets.Normal,
 			presets.Strong,
 		}
 		if err = validate.IsOneOf(*o.PIAEncPreset, validEncryptionPresets...); err != nil {
-			return fmt.Errorf("%w: %w", ErrOpenVPNEncryptionPresetNotValid, err)
+			return fmt.Errorf("PIA encryption preset is not valid: %w", err)
 		}
 	}
 

internal/configuration/settings/pmtud.go

@@ -1,7 +1,6 @@
 package settings
 
 import (
-	"errors"
 	"fmt"
 	"net/netip"
 
@@ -24,21 +23,16 @@ type PMTUD struct {
 	TCPAddresses []netip.AddrPort `json:"tcp_addresses"`
 }
 
-var (
-	ErrPMTUDICMPAddressNotValid = errors.New("PMTUD ICMP address is not valid")
-	ErrPMTUDTCPAddressNotValid  = errors.New("PMTUD TCP address is not valid")
-)
-
 // Validate validates PMTUD settings.
 func (p PMTUD) validate() (err error) {
 	for i, addr := range p.ICMPAddresses {
 		if !addr.IsValid() {
-			return fmt.Errorf("%w: at index %d", ErrPMTUDICMPAddressNotValid, i)
+			return fmt.Errorf("PMTUD ICMP address is not valid: at index %d", i)
 		}
 	}
 	for i, addr := range p.TCPAddresses {
 		if !addr.IsValid() {
-			return fmt.Errorf("%w: at index %d", ErrPMTUDTCPAddressNotValid, i)
+			return fmt.Errorf("PMTUD TCP address is not valid: at index %d", i)
 		}
 	}
 	return nil

internal/configuration/settings/portforward.go

@@ -1,8 +1,10 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"path/filepath"
+	"slices"
 
 	"github.com/qdm12/gluetun/internal/constants/providers"
 	"github.com/qdm12/gosettings"
@@ -37,10 +39,16 @@ type PortForwarding struct {
 	// It can be the empty string to indicate to NOT run a command.
 	// It cannot be nil in the internal state.
 	DownCommand *string `json:"down_command"`
-	// ListeningPort is the port traffic would be redirected to from the
-	// forwarded port. The redirection is disabled if it is set to 0, which
-	// is its default as well.
-	ListeningPort *uint16 `json:"listening_port"`
+	// ListeningPorts are the ports traffic would be redirected to from the
+	// forwarded ports. The redirection is disabled if it is the slice [0],
+	// which is its default as well. If set and not [0], its length must match
+	// the PortsCount value, such that each forwarded port is redirected to
+	// the corresponding listening port.
+	ListeningPorts []uint16 `json:"listening_port"`
+	// PortsCount is the number of ports to forward. It is optional for ProtonVPN
+	// and be between 1 and 5. For other providers, it must be set to 1 if port
+	// forwarding is enabled.
+	PortsCount uint16 `json:"ports_count"`
 	// Username is only used for Private Internet Access port forwarding.
 	Username string `json:"username"`
 	// Password is only used for Private Internet Access port forwarding.
@@ -58,13 +66,12 @@ func (p PortForwarding) Validate(vpnProvider string) (err error) {
 		providerSelected = *p.Provider
 	}
 	validProviders := []string{
-		providers.Perfectprivacy,
 		providers.PrivateInternetAccess,
 		providers.Privatevpn,
 		providers.Protonvpn,
 	}
 	if err = validate.IsOneOf(providerSelected, validProviders...); err != nil {
-		return fmt.Errorf("%w: %w", ErrPortForwardingEnabled, err)
+		return fmt.Errorf("port forwarding cannot be enabled: %w", err)
 	}
 
 	// Validate Filepath
@@ -75,12 +82,36 @@ func (p PortForwarding) Validate(vpnProvider string) (err error) {
 		}
 	}
 
-	if providerSelected == providers.PrivateInternetAccess {
+	switch providerSelected {
+	case providers.PrivateInternetAccess:
+		const maxPortsCount = 1
 		switch {
+		case p.PortsCount > maxPortsCount:
+			return fmt.Errorf("ports count too high: %d > %d", p.PortsCount, maxPortsCount)
 		case p.Username == "":
-			return fmt.Errorf("%w", ErrPortForwardingUserEmpty)
+			return errors.New("port forwarding username is empty")
 		case p.Password == "":
-			return fmt.Errorf("%w", ErrPortForwardingPasswordEmpty)
+			return errors.New("port forwarding password is empty")
+		}
+	case providers.Protonvpn:
+		const maxPortsCount = 5
+		if p.PortsCount > maxPortsCount {
+			return fmt.Errorf("ports count too high: %d > %d", p.PortsCount, maxPortsCount)
+		}
+	default:
+		const maxPortsCount = 1
+		if p.PortsCount > maxPortsCount {
+			return fmt.Errorf("ports count too high: %d > %d", p.PortsCount, maxPortsCount)
+		}
+	}
+
+	if !slices.Equal(p.ListeningPorts, []uint16{0}) {
+		switch {
+		case len(p.ListeningPorts) != int(p.PortsCount):
+			return fmt.Errorf("listening ports length must be equal to ports count: "+
+				"%d != %d", len(p.ListeningPorts), p.PortsCount)
+		case slices.Contains(p.ListeningPorts, 0):
+			return fmt.Errorf("listening port cannot be 0: in %v", p.ListeningPorts)
 		}
 	}
 
@@ -89,14 +120,14 @@ func (p PortForwarding) Validate(vpnProvider string) (err error) {
 
 func (p *PortForwarding) Copy() (copied PortForwarding) {
 	return PortForwarding{
-		Enabled:       gosettings.CopyPointer(p.Enabled),
-		Provider:      gosettings.CopyPointer(p.Provider),
-		Filepath:      gosettings.CopyPointer(p.Filepath),
-		UpCommand:     gosettings.CopyPointer(p.UpCommand),
-		DownCommand:   gosettings.CopyPointer(p.DownCommand),
-		ListeningPort: gosettings.CopyPointer(p.ListeningPort),
-		Username:      p.Username,
-		Password:      p.Password,
+		Enabled:        gosettings.CopyPointer(p.Enabled),
+		Provider:       gosettings.CopyPointer(p.Provider),
+		Filepath:       gosettings.CopyPointer(p.Filepath),
+		UpCommand:      gosettings.CopyPointer(p.UpCommand),
+		DownCommand:    gosettings.CopyPointer(p.DownCommand),
+		ListeningPorts: gosettings.CopySlice(p.ListeningPorts),
+		Username:       p.Username,
+		Password:       p.Password,
 	}
 }
 
@@ -106,7 +137,7 @@ func (p *PortForwarding) OverrideWith(other PortForwarding) {
 	p.Filepath = gosettings.OverrideWithPointer(p.Filepath, other.Filepath)
 	p.UpCommand = gosettings.OverrideWithPointer(p.UpCommand, other.UpCommand)
 	p.DownCommand = gosettings.OverrideWithPointer(p.DownCommand, other.DownCommand)
-	p.ListeningPort = gosettings.OverrideWithPointer(p.ListeningPort, other.ListeningPort)
+	p.ListeningPorts = gosettings.OverrideWithSlice(p.ListeningPorts, other.ListeningPorts)
 	p.Username = gosettings.OverrideWithComparable(p.Username, other.Username)
 	p.Password = gosettings.OverrideWithComparable(p.Password, other.Password)
 }
@@ -117,7 +148,8 @@ func (p *PortForwarding) setDefaults() {
 	p.Filepath = gosettings.DefaultPointer(p.Filepath, "/tmp/gluetun/forwarded_port")
 	p.UpCommand = gosettings.DefaultPointer(p.UpCommand, "")
 	p.DownCommand = gosettings.DefaultPointer(p.DownCommand, "")
-	p.ListeningPort = gosettings.DefaultPointer(p.ListeningPort, 0)
+	p.ListeningPorts = gosettings.DefaultSlice(p.ListeningPorts, []uint16{0}) // disabled
+	p.PortsCount = gosettings.DefaultComparable(p.PortsCount, 1)
 }
 
 func (p PortForwarding) String() string {
@@ -131,11 +163,14 @@ func (p PortForwarding) toLinesNode() (node *gotree.Node) {
 
 	node = gotree.New("Automatic port forwarding settings:")
 
-	listeningPort := "disabled"
-	if *p.ListeningPort != 0 {
-		listeningPort = fmt.Sprintf("%d", *p.ListeningPort)
+	node.Appendf("Number of ports to be forwarded: %d", p.PortsCount)
+
+	if !slices.Equal(p.ListeningPorts, []uint16{0}) {
+		redirNode := node.Appendf("Redirection for listening ports:")
+		for i, port := range p.ListeningPorts {
+			redirNode.Appendf("Port #%d -> %d", i+1, port)
+		}
 	}
-	node.Appendf("Redirection listening port: %s", listeningPort)
 
 	if *p.Provider == "" {
 		node.Appendf("Use port forwarding code for current provider")
@@ -190,7 +225,13 @@ func (p *PortForwarding) read(r *reader.Reader) (err error) {
 	p.DownCommand = r.Get("VPN_PORT_FORWARDING_DOWN_COMMAND",
 		reader.ForceLowercase(false))
 
-	p.ListeningPort, err = r.Uint16Ptr("VPN_PORT_FORWARDING_LISTENING_PORT")
+	p.ListeningPorts, err = r.CSVUint16("VPN_PORT_FORWARDING_LISTENING_PORTS",
+		reader.RetroKeys("VPN_PORT_FORWARDING_LISTENING_PORT"))
+	if err != nil {
+		return err
+	}
+
+	p.PortsCount, err = r.Uint16("VPN_PORT_FORWARDING_PORTS_COUNT")
 	if err != nil {
 		return err
 	}

internal/configuration/settings/provider.go

@@ -30,7 +30,10 @@ type Provider struct {
 func (p *Provider) validate(vpnType string, filterChoicesGetter FilterChoicesGetter, warner Warner) (err error) {
 	// Validate Name
 	var validNames []string
-	if vpnType == vpn.OpenVPN {
+	switch vpnType {
+	case vpn.AmneziaWg:
+		validNames = []string{providers.Custom}
+	case vpn.OpenVPN:
 		validNames = providers.AllWithCustom()
 		validNames = append(validNames, "pia") // Retro-compatibility
 		// Remove Mullvad since it no longer supports OpenVPN as of January 15th, 2026
@@ -38,7 +41,7 @@ func (p *Provider) validate(vpnType string, filterChoicesGetter FilterChoicesGet
 		validNames[mullvadIndex], validNames[len(validNames)-1] = validNames[len(validNames)-1], validNames[mullvadIndex]
 		validNames = validNames[:len(validNames)-1]
 		sort.Strings(validNames)
-	} else { // Wireguard
+	case vpn.Wireguard:
 		validNames = []string{
 			providers.Airvpn,
 			providers.Custom,
@@ -52,7 +55,7 @@ func (p *Provider) validate(vpnType string, filterChoicesGetter FilterChoicesGet
 		}
 	}
 	if err = validate.IsOneOf(p.Name, validNames...); err != nil {
-		return fmt.Errorf("%w for Wireguard: %w", ErrVPNProviderNameNotValid, err)
+		return fmt.Errorf("VPN provider name is not valid for %s: %w", vpnType, err)
 	}
 
 	err = p.ServerSelection.validate(p.Name, filterChoicesGetter, warner)

internal/configuration/settings/publicip_test.go

@@ -3,9 +3,9 @@ package settings
 import (
 	"testing"
 
-	"github.com/golang/mock/gomock"
 	"github.com/qdm12/gosettings/reader"
 	"github.com/stretchr/testify/assert"
+	"go.uber.org/mock/gomock"
 )
 
 func Test_PublicIP_read(t *testing.T) {
@@ -15,7 +15,6 @@ func Test_PublicIP_read(t *testing.T) {
 		makeReader func(ctrl *gomock.Controller) *reader.Reader
 		makeWarner func(ctrl *gomock.Controller) Warner
 		settings   PublicIP
-		errWrapped error
 		errMessage string
 	}{
 		"nothing_read": {
@@ -152,9 +151,10 @@ func Test_PublicIP_read(t *testing.T) {
 			err := settings.read(reader, warner)
 
 			assert.Equal(t, testCase.settings, settings)
-			assert.ErrorIs(t, err, testCase.errWrapped)
-			if testCase.errWrapped != nil {
+			if testCase.errMessage != "" {
 				assert.EqualError(t, err, testCase.errMessage)
+			} else {
+				assert.NoError(t, err)
 			}
 		})
 	}

internal/configuration/settings/server.go

@@ -46,8 +46,7 @@ func (c ControlServer) validate() (err error) {
 	uid := os.Getuid()
 	const maxPrivilegedPort = 1023
 	if uid != 0 && port != 0 && port <= maxPrivilegedPort {
-		return fmt.Errorf("%w: %d when running with user ID %d",
-			ErrControlServerPrivilegedPort, port, uid)
+		return fmt.Errorf("cannot use privileged port without running as root: %d when running with user ID %d", port, uid)
 	}
 
 	jsonDecoder := json.NewDecoder(bytes.NewBufferString(c.AuthDefaultRole))
@@ -96,7 +95,7 @@ func (c *ControlServer) setDefaults() {
 		var role auth.Role
 		_ = json.Unmarshal([]byte(c.AuthDefaultRole), &role)
 		role.Name = "default"
-		roleBytes, _ := json.Marshal(role) //nolint:errchkjson
+		roleBytes, _ := json.Marshal(role) //nolint:errchkjson,gosec
 		c.AuthDefaultRole = string(roleBytes)
 	}
 }

internal/configuration/settings/serverselection.go

@@ -71,25 +71,13 @@ type ServerSelection struct {
 	Wireguard WireguardSelection `json:"wireguard"`
 }
 
-var (
-	ErrOwnedOnlyNotSupported       = errors.New("owned only filter is not supported")
-	ErrFreeOnlyNotSupported        = errors.New("free only filter is not supported")
-	ErrPremiumOnlyNotSupported     = errors.New("premium only filter is not supported")
-	ErrStreamOnlyNotSupported      = errors.New("stream only filter is not supported")
-	ErrMultiHopOnlyNotSupported    = errors.New("multi hop only filter is not supported")
-	ErrPortForwardOnlyNotSupported = errors.New("port forwarding only filter is not supported")
-	ErrFreePremiumBothSet          = errors.New("free only and premium only filters are both set")
-	ErrSecureCoreOnlyNotSupported  = errors.New("secure core only filter is not supported")
-	ErrTorOnlyNotSupported         = errors.New("tor only filter is not supported")
-)
-
 func (ss *ServerSelection) validate(vpnServiceProvider string,
 	filterChoicesGetter FilterChoicesGetter, warner Warner,
 ) (err error) {
 	switch ss.VPN {
-	case vpn.OpenVPN, vpn.Wireguard:
+	case vpn.AmneziaWg, vpn.OpenVPN, vpn.Wireguard:
 	default:
-		return fmt.Errorf("%w: %s", ErrVPNTypeNotValid, ss.VPN)
+		return fmt.Errorf("VPN type is not valid: %s", ss.VPN)
 	}
 
 	filterChoices, err := getLocationFilterChoices(vpnServiceProvider, ss, filterChoicesGetter, warner)
@@ -150,7 +138,7 @@ func getLocationFilterChoices(vpnServiceProvider string,
 			// Only return error comparing with newer regions, we don't want to confuse the user
 			// with the retro regions in the error message.
 			err = atLeastOneIsOneOfCaseInsensitive(ss.Regions, filterChoices.Regions, warner)
-			return models.FilterChoices{}, fmt.Errorf("%w: %w", ErrRegionNotValid, err)
+			return models.FilterChoices{}, fmt.Errorf("the region specified is not valid: %w", err)
 		}
 	}
 
@@ -164,27 +152,27 @@ func validateServerFilters(settings ServerSelection, filterChoices models.Filter
 ) (err error) {
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Countries, filterChoices.Countries, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrCountryNotValid, err)
+		return fmt.Errorf("the country specified is not valid: %w", err)
 	}
 
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Regions, filterChoices.Regions, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrRegionNotValid, err)
+		return fmt.Errorf("the region specified is not valid: %w", err)
 	}
 
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Cities, filterChoices.Cities, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrCityNotValid, err)
+		return fmt.Errorf("the city specified is not valid: %w", err)
 	}
 
 	err = atLeastOneIsOneOfCaseInsensitive(settings.ISPs, filterChoices.ISPs, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrISPNotValid, err)
+		return fmt.Errorf("the ISP specified is not valid: %w", err)
 	}
 
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Hostnames, filterChoices.Hostnames, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrHostnameNotValid, err)
+		return fmt.Errorf("the hostname specified is not valid: %w", err)
 	}
 
 	if vpnServiceProvider == providers.Custom {
@@ -196,19 +184,19 @@ func validateServerFilters(settings ServerSelection, filterChoices models.Filter
 			// which requires a server name for TLS verification.
 			filterChoices.Names = settings.Names
 		default:
-			return fmt.Errorf("%w: %d names specified instead of "+
-				"0 or 1 for the custom provider",
-				ErrNameNotValid, len(settings.Names))
+			return fmt.Errorf("name is not valid: "+
+				"%d names specified instead of 0 or 1 for the custom provider",
+				len(settings.Names))
 		}
 	}
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Names, filterChoices.Names, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrNameNotValid, err)
+		return fmt.Errorf("the server name specified is not valid: %w", err)
 	}
 
 	err = atLeastOneIsOneOfCaseInsensitive(settings.Categories, filterChoices.Categories, warner)
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrCategoryNotValid, err)
+		return fmt.Errorf("the category specified is not valid: %w", err)
 	}
 
 	return nil
@@ -255,12 +243,12 @@ func validateSubscriptionTierFilters(settings ServerSelection, vpnServiceProvide
 	switch {
 	case *settings.FreeOnly &&
 		!helpers.IsOneOf(vpnServiceProvider, providers.Protonvpn, providers.VPNUnlimited):
-		return fmt.Errorf("%w", ErrFreeOnlyNotSupported)
+		return errors.New("free only filter is not supported")
 	case *settings.PremiumOnly &&
 		!helpers.IsOneOf(vpnServiceProvider, providers.VPNSecure):
-		return fmt.Errorf("%w", ErrPremiumOnlyNotSupported)
+		return errors.New("premium only filter is not supported")
 	case *settings.FreeOnly && *settings.PremiumOnly:
-		return fmt.Errorf("%w", ErrFreePremiumBothSet)
+		return errors.New("free only and premium only filters are both set")
 	default:
 		return nil
 	}
@@ -269,21 +257,21 @@ func validateSubscriptionTierFilters(settings ServerSelection, vpnServiceProvide
 func validateFeatureFilters(settings ServerSelection, vpnServiceProvider string) error {
 	switch {
 	case *settings.OwnedOnly && vpnServiceProvider != providers.Mullvad:
-		return fmt.Errorf("%w", ErrOwnedOnlyNotSupported)
+		return errors.New("owned only filter is not supported")
 	case vpnServiceProvider == providers.Protonvpn && *settings.FreeOnly && *settings.PortForwardOnly:
-		return fmt.Errorf("%w: together with free only filter", ErrPortForwardOnlyNotSupported)
+		return errors.New("port forwarding only filter is not supported: together with free only filter")
 	case *settings.StreamOnly &&
 		!helpers.IsOneOf(vpnServiceProvider, providers.Protonvpn, providers.VPNUnlimited):
-		return fmt.Errorf("%w", ErrStreamOnlyNotSupported)
+		return errors.New("stream only filter is not supported")
 	case *settings.MultiHopOnly && vpnServiceProvider != providers.Surfshark:
-		return fmt.Errorf("%w", ErrMultiHopOnlyNotSupported)
+		return errors.New("multi hop only filter is not supported")
 	case *settings.PortForwardOnly &&
 		!helpers.IsOneOf(vpnServiceProvider, providers.PrivateInternetAccess, providers.Protonvpn):
-		return fmt.Errorf("%w", ErrPortForwardOnlyNotSupported)
+		return errors.New("port forwarding only filter is not supported")
 	case *settings.SecureCoreOnly && vpnServiceProvider != providers.Protonvpn:
-		return fmt.Errorf("%w", ErrSecureCoreOnlyNotSupported)
+		return errors.New("secure core only filter is not supported")
 	case *settings.TorOnly && vpnServiceProvider != providers.Protonvpn:
-		return fmt.Errorf("%w", ErrTorOnlyNotSupported)
+		return errors.New("tor only filter is not supported")
 	default:
 		return nil
 	}
@@ -518,7 +506,8 @@ func (ss *ServerSelection) read(r *reader.Reader,
 		return err
 	}
 
-	err = ss.Wireguard.read(r)
+	amneziawg := ss.VPN == vpn.AmneziaWg
+	err = ss.Wireguard.read(r, amneziawg)
 	if err != nil {
 		return err
 	}

internal/configuration/settings/settings.go

@@ -2,7 +2,6 @@ package settings
 
 import (
 	"fmt"
-	"net/netip"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
 	"github.com/qdm12/gluetun/internal/constants/providers"
@@ -21,13 +20,16 @@ type Settings struct {
 	HTTPProxy     HTTPProxy
 	Log           Log
 	PublicIP      PublicIP
+	Socks5        Socks5
 	Shadowsocks   Shadowsocks
 	Storage       Storage
 	System        System
 	Updater       Updater
 	Version       Version
 	VPN           VPN
+	IPv6          IPv6
 	Pprof         pprof.Settings
+	BoringPoll    BoringPoll
 }
 
 type FilterChoicesGetter interface {
@@ -48,15 +50,18 @@ func (s *Settings) Validate(filterChoicesGetter FilterChoicesGetter, ipv6Support
 		"http proxy":      s.HTTPProxy.validate,
 		"log":             s.Log.validate,
 		"public ip check": s.PublicIP.validate,
+		"socks5":          s.Socks5.validate,
 		"shadowsocks":     s.Shadowsocks.validate,
 		"storage":         s.Storage.validate,
 		"system":          s.System.validate,
 		"updater":         s.Updater.Validate,
 		"version":         s.Version.validate,
+		"ipv6":            s.IPv6.validate,
 		// Pprof validation done in pprof constructor
 		"VPN": func() error {
 			return s.VPN.Validate(filterChoicesGetter, ipv6Supported, warner)
 		},
+		"boring poll": s.BoringPoll.validate,
 	}
 
 	for name, validation := range nameToValidation {
@@ -78,6 +83,7 @@ func (s *Settings) copy() (copied Settings) {
 		HTTPProxy:     s.HTTPProxy.copy(),
 		Log:           s.Log.copy(),
 		PublicIP:      s.PublicIP.copy(),
+		Socks5:        s.Socks5.copy(),
 		Shadowsocks:   s.Shadowsocks.copy(),
 		Storage:       s.Storage.copy(),
 		System:        s.System.copy(),
@@ -85,6 +91,8 @@ func (s *Settings) copy() (copied Settings) {
 		Version:       s.Version.copy(),
 		VPN:           s.VPN.Copy(),
 		Pprof:         s.Pprof.Copy(),
+		BoringPoll:    s.BoringPoll.Copy(),
+		IPv6:          s.IPv6.copy(),
 	}
 }
 
@@ -99,6 +107,7 @@ func (s *Settings) OverrideWith(other Settings,
 	patchedSettings.HTTPProxy.overrideWith(other.HTTPProxy)
 	patchedSettings.Log.overrideWith(other.Log)
 	patchedSettings.PublicIP.overrideWith(other.PublicIP)
+	patchedSettings.Socks5.overrideWith(other.Socks5)
 	patchedSettings.Shadowsocks.overrideWith(other.Shadowsocks)
 	patchedSettings.Storage.overrideWith(other.Storage)
 	patchedSettings.System.overrideWith(other.System)
@@ -106,6 +115,8 @@ func (s *Settings) OverrideWith(other Settings,
 	patchedSettings.Version.overrideWith(other.Version)
 	patchedSettings.VPN.OverrideWith(other.VPN)
 	patchedSettings.Pprof.OverrideWith(other.Pprof)
+	patchedSettings.BoringPoll.overrideWith(other.BoringPoll)
+	patchedSettings.IPv6.overrideWith(other.IPv6)
 	err = patchedSettings.Validate(filterChoicesGetter, ipv6Supported, warner)
 	if err != nil {
 		return err
@@ -117,18 +128,22 @@ func (s *Settings) OverrideWith(other Settings,
 func (s *Settings) SetDefaults() {
 	s.ControlServer.setDefaults()
 	s.DNS.setDefaults()
-	s.Firewall.setDefaults()
+	s.Log.setDefaults()
+	s.Firewall.setDefaults(s.Log.Level)
 	s.Health.SetDefaults()
 	s.HTTPProxy.setDefaults()
 	s.Log.setDefaults()
+	s.IPv6.setDefaults()
 	s.PublicIP.setDefaults()
+	s.Socks5.setDefaults()
 	s.Shadowsocks.setDefaults()
-	s.Storage.setDefaults()
+	s.Storage.SetDefaults()
 	s.System.setDefaults()
 	s.Version.setDefaults()
 	s.VPN.setDefaults()
 	s.Updater.SetDefaults(s.VPN.Provider.Name)
 	s.Pprof.SetDefaults()
+	s.BoringPoll.setDefaults()
 }
 
 func (s Settings) String() string {
@@ -142,7 +157,9 @@ func (s Settings) toLinesNode() (node *gotree.Node) {
 	node.AppendNode(s.DNS.toLinesNode())
 	node.AppendNode(s.Firewall.toLinesNode())
 	node.AppendNode(s.Log.toLinesNode())
+	node.AppendNode(s.IPv6.toLinesNode())
 	node.AppendNode(s.Health.toLinesNode())
+	node.AppendNode(s.Socks5.toLinesNode())
 	node.AppendNode(s.Shadowsocks.toLinesNode())
 	node.AppendNode(s.HTTPProxy.toLinesNode())
 	node.AppendNode(s.ControlServer.toLinesNode())
@@ -152,6 +169,7 @@ func (s Settings) toLinesNode() (node *gotree.Node) {
 	node.AppendNode(s.Updater.toLinesNode())
 	node.AppendNode(s.Version.toLinesNode())
 	node.AppendNode(s.Pprof.ToLinesNode())
+	node.AppendNode(s.BoringPoll.toLinesNode())
 
 	return node
 }
@@ -174,13 +192,11 @@ func (s Settings) Warnings() (warnings []string) {
 			"by creating an issue, attaching the new certificate and we will update Gluetun.")
 	}
 
-	// TODO remove in v4
-	if s.DNS.ServerAddress.Unmap().Compare(netip.AddrFrom4([4]byte{127, 0, 0, 1})) != 0 {
-		warnings = append(warnings, "DNS address is set to "+s.DNS.ServerAddress.String()+
-			" so the local forwarding DNS server will not be used."+
-			" The default value changed to 127.0.0.1 so it uses the internal DNS server."+
-			" If this server fails to start, the IPv4 address of the first plaintext DNS server"+
-			" corresponding to the first DNS provider chosen is used.")
+	for _, upstreamAddress := range s.DNS.UpstreamPlainAddresses {
+		if upstreamAddress.Addr().IsPrivate() {
+			warnings = append(warnings, "DNS upstream address "+upstreamAddress.String()+" is private: "+
+				"DNS traffic might leak out of the VPN tunnel to that address.")
+		}
 	}
 
 	return warnings
@@ -202,13 +218,16 @@ func (s *Settings) Read(r *reader.Reader, warner Warner) (err error) {
 		"public ip": func(r *reader.Reader) error {
 			return s.PublicIP.read(r, warner)
 		},
+		"socks5":      s.Socks5.read,
 		"shadowsocks": s.Shadowsocks.read,
-		"storage":     s.Storage.read,
+		"storage":     s.Storage.Read,
 		"system":      s.System.read,
 		"updater":     s.Updater.read,
 		"version":     s.Version.read,
 		"VPN":         s.VPN.read,
+		"IPv6":        s.IPv6.read,
 		"profiling":   s.Pprof.Read,
+		"boring poll": s.BoringPoll.read,
 	}
 
 	for name, read := range readFunctions {

internal/configuration/settings/settings_test.go

@@ -51,9 +51,6 @@ func Test_Settings_String(t *testing.T) {
 |           ├── [2606:4700:4700::1111]:443
 |           └── [2001:4860:4860::8888]:443
 ├── DNS settings:
-|   ├── Keep existing nameserver(s): no
-|   ├── DNS server address to use: 127.0.0.1
-|   ├── DNS forwarder server enabled: yes
 |   ├── Upstream resolver type: dot
 |   ├── Upstream resolvers:
 |   |   └── Cloudflare
@@ -62,13 +59,18 @@ func Test_Settings_String(t *testing.T) {
 |   ├── Update period: every 24h0m0s
 |   └── DNS filtering settings:
 |       ├── Block malicious: yes
-|       ├── Block ads: no
-|       └── Block surveillance: yes
+|       └── Block ads: no
 ├── Firewall settings:
 |   ├── Enabled: yes
-|   └── Implementation: iptables
+|   ├── Implementation: iptables
+|   └── Iptables settings:
+|       └── Log level: INFO
 ├── Log settings:
 |   └── Log level: INFO
+├── IPv6 settings:
+|   └── Check addresses:
+|       ├── [2001:4860:4860::8888]:53
+|       └── [2606:4700:4700::1111]:53
 ├── Health settings:
 |   ├── Server listening address: 127.0.0.1:9999
 |   ├── Target addresses:
@@ -79,6 +81,8 @@ func Test_Settings_String(t *testing.T) {
 |   |       ├── 1.1.1.1
 |   |       └── 8.8.8.8
 |   └── Restart VPN on healthcheck failure: yes
+├── SOCKS5 proxy server settings:
+|   └── Enabled: no
 ├── Shadowsocks server settings:
 |   └── Enabled: no
 ├── HTTP proxy settings:
@@ -88,7 +92,7 @@ func Test_Settings_String(t *testing.T) {
 |   ├── Logging: yes
 |   └── Authentication file path: /gluetun/auth/config.toml
 ├── Storage settings:
-|   └── Filepath: /gluetun/servers.json
+|   └── Servers directory path: /gluetun/servers/
 ├── OS Alpine settings:
 |   ├── Process UID: 1000
 |   └── Process GID: 1000

internal/configuration/settings/socks5.go

@@ -0,0 +1,91 @@
+package settings
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/qdm12/gosettings"
+	"github.com/qdm12/gosettings/reader"
+	"github.com/qdm12/gosettings/validate"
+	"github.com/qdm12/gotree"
+)
+
+// Socks5 contains settings to configure the Socks5 proxy server.
+type Socks5 struct {
+	Enabled          *bool
+	ListeningAddress string
+	Username         *string
+	Password         *string
+}
+
+func (s Socks5) validate() (err error) {
+	err = validate.ListeningAddress(s.ListeningAddress, os.Getuid())
+	if err != nil {
+		return fmt.Errorf("server listening address is not valid: %w", err)
+	}
+
+	switch {
+	case *s.Username != "" && *s.Password == "":
+		return errors.New("password must be set if username is set")
+	case *s.Username == "" && *s.Password != "":
+		return errors.New("username must be set if password is set")
+	}
+
+	return nil
+}
+
+func (s *Socks5) copy() (copied Socks5) {
+	return Socks5{
+		Enabled:          gosettings.CopyPointer(s.Enabled),
+		ListeningAddress: s.ListeningAddress,
+		Username:         gosettings.CopyPointer(s.Username),
+		Password:         gosettings.CopyPointer(s.Password),
+	}
+}
+
+func (s *Socks5) overrideWith(other Socks5) {
+	s.Enabled = gosettings.OverrideWithPointer(s.Enabled, other.Enabled)
+	s.ListeningAddress = gosettings.OverrideWithComparable(s.ListeningAddress, other.ListeningAddress)
+	s.Username = gosettings.OverrideWithPointer(s.Username, other.Username)
+	s.Password = gosettings.OverrideWithPointer(s.Password, other.Password)
+}
+
+func (s *Socks5) setDefaults() {
+	s.Enabled = gosettings.DefaultPointer(s.Enabled, false)
+	s.ListeningAddress = gosettings.DefaultComparable(s.ListeningAddress, ":1080")
+	s.Username = gosettings.DefaultPointer(s.Username, "")
+	s.Password = gosettings.DefaultPointer(s.Password, "")
+}
+
+func (s Socks5) String() string {
+	return s.toLinesNode().String()
+}
+
+func (s Socks5) toLinesNode() (node *gotree.Node) {
+	node = gotree.New("SOCKS5 proxy server settings:")
+	node.Appendf("Enabled: %s", gosettings.BoolToYesNo(s.Enabled))
+	if !*s.Enabled {
+		return node
+	}
+
+	node.Appendf("Listening address: %s", s.ListeningAddress)
+	if *s.Username != "" || *s.Password != "" {
+		node.Appendf("Username: %s", *s.Username)
+		node.Appendf("Password: %s", gosettings.ObfuscateKey(*s.Password))
+	}
+	return node
+}
+
+func (s *Socks5) read(r *reader.Reader) (err error) {
+	s.Enabled, err = r.BoolPtr("SOCKS5_ENABLED")
+	if err != nil {
+		return err
+	}
+
+	s.ListeningAddress = r.String("SOCKS5_LISTENING_ADDRESS")
+	s.Username = r.Get("SOCKS5_USER", reader.ForceLowercase(false))
+	s.Password = r.Get("SOCKS5_PASSWORD", reader.ForceLowercase(false))
+
+	return nil
+}

internal/configuration/settings/storage.go

@@ -11,15 +11,26 @@ import (
 
 // Storage contains settings to configure the storage.
 type Storage struct {
-	// Filepath is the path to the servers.json file. An empty string disables on-disk storage.
-	Filepath *string
+	// ServersEnabled is whether to enable storage of servers on disk.
+	// It defaults to true.
+	ServersEnabled *bool
+	// ServersPath is the path to the servers files directory, and cannot be
+	// the empty string.
+	ServersPath string
+	// LegacyServersFilepath is the legacy "fat" JSON filepath to migrate from.
+	// TODO v4: remove
+	LegacyServersFilepath string
 }
 
 func (s Storage) validate() (err error) {
-	if *s.Filepath != "" { // optional
-		_, err := filepath.Abs(*s.Filepath)
+	if *s.ServersEnabled {
+		_, err := filepath.Abs(s.ServersPath)
 		if err != nil {
-			return fmt.Errorf("filepath is not valid: %w", err)
+			return fmt.Errorf("servers path is not valid: %w", err)
+		}
+		_, err = filepath.Abs(s.LegacyServersFilepath)
+		if err != nil {
+			return fmt.Errorf("legacy servers filepath is not valid: %w", err)
 		}
 	}
 	return nil
@@ -27,17 +38,25 @@ func (s Storage) validate() (err error) {
 
 func (s *Storage) copy() (copied Storage) {
 	return Storage{
-		Filepath: gosettings.CopyPointer(s.Filepath),
+		ServersEnabled:        gosettings.CopyPointer(s.ServersEnabled),
+		ServersPath:           s.ServersPath,
+		LegacyServersFilepath: s.LegacyServersFilepath,
 	}
 }
 
 func (s *Storage) overrideWith(other Storage) {
-	s.Filepath = gosettings.OverrideWithPointer(s.Filepath, other.Filepath)
+	s.ServersEnabled = gosettings.OverrideWithPointer(s.ServersEnabled, other.ServersEnabled)
+	s.ServersPath = gosettings.OverrideWithComparable(s.ServersPath, other.ServersPath)
+	s.LegacyServersFilepath = gosettings.OverrideWithComparable(s.LegacyServersFilepath, other.LegacyServersFilepath)
 }
 
-func (s *Storage) setDefaults() {
-	const defaultFilepath = "/gluetun/servers.json"
-	s.Filepath = gosettings.DefaultPointer(s.Filepath, defaultFilepath)
+const defaultLegacyServersFilepath = "/gluetun/servers.json"
+
+func (s *Storage) SetDefaults() {
+	s.ServersEnabled = gosettings.DefaultPointer(s.ServersEnabled, true)
+	const defaultServersPath = "/gluetun/servers/"
+	s.ServersPath = gosettings.DefaultComparable(s.ServersPath, defaultServersPath)
+	s.LegacyServersFilepath = gosettings.DefaultComparable(s.LegacyServersFilepath, defaultLegacyServersFilepath)
 }
 
 func (s Storage) String() string {
@@ -45,15 +64,33 @@ func (s Storage) String() string {
 }
 
 func (s Storage) toLinesNode() (node *gotree.Node) {
-	if *s.Filepath == "" {
+	if !*s.ServersEnabled {
 		return gotree.New("Storage settings: disabled")
 	}
 	node = gotree.New("Storage settings:")
-	node.Appendf("Filepath: %s", *s.Filepath)
+	node.Appendf("Servers directory path: %s", s.ServersPath)
+	if s.LegacyServersFilepath != defaultLegacyServersFilepath {
+		node.Appendf("Legacy servers filepath: %s", s.LegacyServersFilepath)
+	}
 	return node
 }
 
-func (s *Storage) read(r *reader.Reader) (err error) {
-	s.Filepath = r.Get("STORAGE_FILEPATH", reader.AcceptEmpty(true))
+func (s *Storage) Read(r *reader.Reader) (err error) {
+	// Retro-compatibility:
+	// TODO v4: remove support for STORAGE_FILEPATH
+	filePath := r.Get("STORAGE_FILEPATH", reader.AcceptEmpty(true), reader.IsRetro("STORAGE_SERVERS_DIRECTORY_PATH"))
+	if filePath != nil {
+		if *filePath == "" {
+			s.ServersEnabled = ptrTo(false)
+		} else {
+			s.LegacyServersFilepath = *filePath
+		}
+	} else {
+		s.ServersEnabled, err = r.BoolPtr("STORAGE_SERVERS_ENABLED")
+		if err != nil {
+			return err
+		}
+		s.ServersPath = r.String("STORAGE_SERVERS_DIRECTORY_PATH")
+	}
 	return nil
 }

internal/configuration/settings/updater.go

@@ -1,6 +1,7 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"slices"
 	"strings"
@@ -21,10 +22,6 @@ type Updater struct {
 	// updater. It cannot be nil in the internal state.
 	// TODO change to value and add Enabled field.
 	Period *time.Duration
-	// DNSAddress is the DNS server address to use
-	// to resolve VPN server hostnames to IP addresses.
-	// It cannot be the empty string in the internal state.
-	DNSAddress string
 	// MinRatio is the minimum ratio of servers to
 	// find per provider, compared to the total current
 	// number of servers. It defaults to 0.8.
@@ -32,6 +29,9 @@ type Updater struct {
 	// Providers is the list of VPN service providers
 	// to update server information for.
 	Providers []string
+	// PreferDirectDownload is whether to prefer direct download of
+	// server data from Github (recommended).
+	PreferDirectDownload *bool
 	// ProtonEmail is the email to authenticate with the Proton API.
 	ProtonEmail *string
 	// ProtonPassword is the password to authenticate with the Proton API.
@@ -41,20 +41,20 @@ type Updater struct {
 func (u Updater) Validate() (err error) {
 	const minPeriod = time.Minute
 	if *u.Period > 0 && *u.Period < minPeriod {
-		return fmt.Errorf("%w: %d must be larger than %s",
-			ErrUpdaterPeriodTooSmall, *u.Period, minPeriod)
+		return fmt.Errorf("VPN server data updater period is too small: "+
+			"%d must be larger than %s", *u.Period, minPeriod)
 	}
 
 	if u.MinRatio <= 0 || u.MinRatio > 1 {
-		return fmt.Errorf("%w: %.2f must be between 0+ and 1",
-			ErrMinRatioNotValid, u.MinRatio)
+		return fmt.Errorf("minimum ratio is not valid: "+
+			"%.2f must be between 0+ and 1", u.MinRatio)
 	}
 
 	validProviders := providers.All()
 	for _, provider := range u.Providers {
 		err = validate.IsOneOf(provider, validProviders...)
 		if err != nil {
-			return fmt.Errorf("%w: %w", ErrVPNProviderNameNotValid, err)
+			return fmt.Errorf("VPN provider name is not valid: %w", err)
 		}
 
 		if provider == providers.Protonvpn {
@@ -62,9 +62,9 @@ func (u Updater) Validate() (err error) {
 			if authenticatedAPI {
 				switch {
 				case *u.ProtonEmail == "":
-					return fmt.Errorf("%w", ErrUpdaterProtonEmailMissing)
+					return errors.New("proton email is missing")
 				case *u.ProtonPassword == "":
-					return fmt.Errorf("%w", ErrUpdaterProtonPasswordMissing)
+					return errors.New("proton password is missing")
 				}
 			}
 		}
@@ -75,12 +75,12 @@ func (u Updater) Validate() (err error) {
 
 func (u *Updater) copy() (copied Updater) {
 	return Updater{
-		Period:         gosettings.CopyPointer(u.Period),
-		DNSAddress:     u.DNSAddress,
-		MinRatio:       u.MinRatio,
-		Providers:      gosettings.CopySlice(u.Providers),
-		ProtonEmail:    gosettings.CopyPointer(u.ProtonEmail),
-		ProtonPassword: gosettings.CopyPointer(u.ProtonPassword),
+		Period:               gosettings.CopyPointer(u.Period),
+		MinRatio:             u.MinRatio,
+		Providers:            gosettings.CopySlice(u.Providers),
+		PreferDirectDownload: gosettings.CopyPointer(u.PreferDirectDownload),
+		ProtonEmail:          gosettings.CopyPointer(u.ProtonEmail),
+		ProtonPassword:       gosettings.CopyPointer(u.ProtonPassword),
 	}
 }
 
@@ -89,16 +89,15 @@ func (u *Updater) copy() (copied Updater) {
 // settings.
 func (u *Updater) overrideWith(other Updater) {
 	u.Period = gosettings.OverrideWithPointer(u.Period, other.Period)
-	u.DNSAddress = gosettings.OverrideWithComparable(u.DNSAddress, other.DNSAddress)
 	u.MinRatio = gosettings.OverrideWithComparable(u.MinRatio, other.MinRatio)
 	u.Providers = gosettings.OverrideWithSlice(u.Providers, other.Providers)
+	u.PreferDirectDownload = gosettings.OverrideWithPointer(u.PreferDirectDownload, other.PreferDirectDownload)
 	u.ProtonEmail = gosettings.OverrideWithPointer(u.ProtonEmail, other.ProtonEmail)
 	u.ProtonPassword = gosettings.OverrideWithPointer(u.ProtonPassword, other.ProtonPassword)
 }
 
 func (u *Updater) SetDefaults(vpnProvider string) {
 	u.Period = gosettings.DefaultPointer(u.Period, 0)
-	u.DNSAddress = gosettings.DefaultComparable(u.DNSAddress, "1.1.1.1:53")
 
 	if u.MinRatio == 0 {
 		const defaultMinRatio = 0.8
@@ -110,6 +109,7 @@ func (u *Updater) SetDefaults(vpnProvider string) {
 	}
 
 	// Set these to empty strings to avoid nil pointer panics
+	u.PreferDirectDownload = gosettings.DefaultPointer(u.PreferDirectDownload, false)
 	u.ProtonEmail = gosettings.DefaultPointer(u.ProtonEmail, "")
 	u.ProtonPassword = gosettings.DefaultPointer(u.ProtonPassword, "")
 }
@@ -125,9 +125,9 @@ func (u Updater) toLinesNode() (node *gotree.Node) {
 
 	node = gotree.New("Server data updater settings:")
 	node.Appendf("Update period: %s", *u.Period)
-	node.Appendf("DNS address: %s", u.DNSAddress)
 	node.Appendf("Minimum ratio: %.1f", u.MinRatio)
 	node.Appendf("Providers to update: %s", strings.Join(u.Providers, ", "))
+	node.Appendf("Prefer direct download: %s", gosettings.BoolToYesNo(u.PreferDirectDownload))
 	if slices.Contains(u.Providers, providers.Protonvpn) {
 		node.Appendf("Proton API email: %s", *u.ProtonEmail)
 		node.Appendf("Proton API password: %s", gosettings.ObfuscateKey(*u.ProtonPassword))
@@ -142,11 +142,6 @@ func (u *Updater) read(r *reader.Reader) (err error) {
 		return err
 	}
 
-	u.DNSAddress, err = readUpdaterDNSAddress()
-	if err != nil {
-		return err
-	}
-
 	u.MinRatio, err = r.Float64("UPDATER_MIN_RATIO")
 	if err != nil {
 		return err
@@ -154,6 +149,11 @@ func (u *Updater) read(r *reader.Reader) (err error) {
 
 	u.Providers = r.CSV("UPDATER_VPN_SERVICE_PROVIDERS")
 
+	u.PreferDirectDownload, err = r.BoolPtr("UPDATER_PREFER_DIRECT_DOWNLOAD")
+	if err != nil {
+		return err
+	}
+
 	u.ProtonEmail = r.Get("UPDATER_PROTONVPN_EMAIL")
 	if u.ProtonEmail == nil {
 		protonUsername := r.String("UPDATER_PROTONVPN_USERNAME", reader.IsRetro("UPDATER_PROTONVPN_EMAIL"))
@@ -166,12 +166,3 @@ func (u *Updater) read(r *reader.Reader) (err error) {
 
 	return nil
 }
-
-func readUpdaterDNSAddress() (address string, err error) {
-	// TODO this is currently using Cloudflare in
-	// plaintext to not be blocked by DNS over TLS by default.
-	// If a plaintext address is set in the DNS settings, this one will be used.
-	// use custom future encrypted DNS written in Go without blocking
-	// as it's too much trouble to start another parallel unbound instance for now.
-	return "", nil
-}

internal/configuration/settings/vpn.go

@@ -16,17 +16,28 @@ type VPN struct {
 	// empty string in the internal state.
 	Type      string    `json:"type"`
 	Provider  Provider  `json:"provider"`
+	AmneziaWg AmneziaWg `json:"amneziawg"`
 	OpenVPN   OpenVPN   `json:"openvpn"`
 	Wireguard Wireguard `json:"wireguard"`
 	PMTUD     PMTUD     `json:"pmtud"`
+	// UpCommand is the command to use when the VPN connection is up.
+	// It can be the empty string to indicate not to run a command.
+	// It cannot be nil in the internal state.
+	UpCommand *string `json:"up_command"`
+	// DownCommand is the command to use after the VPN connection goes down.
+	// It can be the empty string to indicate to NOT run a command.
+	// It cannot be nil in the internal state.
+	DownCommand *string `json:"down_command"`
 }
 
+// Validate validates VPN settings, using the filter choices getter (aka servers data storage),
+// and if IPv6 is supported or not.
 // TODO v4 remove pointer for receiver (because of Surfshark).
 func (v *VPN) Validate(filterChoicesGetter FilterChoicesGetter, ipv6Supported bool, warner Warner) (err error) {
 	// Validate Type
-	validVPNTypes := []string{vpn.OpenVPN, vpn.Wireguard}
+	validVPNTypes := []string{vpn.AmneziaWg, vpn.OpenVPN, vpn.Wireguard}
 	if err = validate.IsOneOf(v.Type, validVPNTypes...); err != nil {
-		return fmt.Errorf("%w: %w", ErrVPNTypeNotValid, err)
+		return fmt.Errorf("VPN type is not valid: %w", err)
 	}
 
 	err = v.Provider.validate(v.Type, filterChoicesGetter, warner)
@@ -34,13 +45,20 @@ func (v *VPN) Validate(filterChoicesGetter FilterChoicesGetter, ipv6Supported bo
 		return fmt.Errorf("provider settings: %w", err)
 	}
 
-	if v.Type == vpn.OpenVPN {
+	switch v.Type {
+	case vpn.AmneziaWg:
+		err = v.AmneziaWg.validate(v.Provider.Name, ipv6Supported)
+		if err != nil {
+			return fmt.Errorf("AmneziaWG settings: %w", err)
+		}
+	case vpn.OpenVPN:
 		err := v.OpenVPN.validate(v.Provider.Name)
 		if err != nil {
 			return fmt.Errorf("OpenVPN settings: %w", err)
 		}
-	} else {
-		err := v.Wireguard.validate(v.Provider.Name, ipv6Supported)
+	case vpn.Wireguard:
+		const amneziawg = false
+		err := v.Wireguard.validate(v.Provider.Name, ipv6Supported, amneziawg)
 		if err != nil {
 			return fmt.Errorf("Wireguard settings: %w", err)
 		}
@@ -56,28 +74,37 @@ func (v *VPN) Validate(filterChoicesGetter FilterChoicesGetter, ipv6Supported bo
 
 func (v *VPN) Copy() (copied VPN) {
 	return VPN{
-		Type:      v.Type,
-		Provider:  v.Provider.copy(),
-		OpenVPN:   v.OpenVPN.copy(),
-		Wireguard: v.Wireguard.copy(),
-		PMTUD:     v.PMTUD.copy(),
+		Type:        v.Type,
+		Provider:    v.Provider.copy(),
+		AmneziaWg:   v.AmneziaWg.copy(),
+		OpenVPN:     v.OpenVPN.copy(),
+		Wireguard:   v.Wireguard.copy(),
+		PMTUD:       v.PMTUD.copy(),
+		UpCommand:   gosettings.CopyPointer(v.UpCommand),
+		DownCommand: gosettings.CopyPointer(v.DownCommand),
 	}
 }
 
 func (v *VPN) OverrideWith(other VPN) {
 	v.Type = gosettings.OverrideWithComparable(v.Type, other.Type)
 	v.Provider.overrideWith(other.Provider)
+	v.AmneziaWg.overrideWith(other.AmneziaWg)
 	v.OpenVPN.overrideWith(other.OpenVPN)
 	v.Wireguard.overrideWith(other.Wireguard)
 	v.PMTUD.overrideWith(other.PMTUD)
+	v.UpCommand = gosettings.OverrideWithPointer(v.UpCommand, other.UpCommand)
+	v.DownCommand = gosettings.OverrideWithPointer(v.DownCommand, other.DownCommand)
 }
 
 func (v *VPN) setDefaults() {
 	v.Type = gosettings.DefaultComparable(v.Type, vpn.OpenVPN)
 	v.Provider.setDefaults()
+	v.AmneziaWg.setDefaults(v.Provider.Name)
 	v.OpenVPN.setDefaults(v.Provider.Name)
 	v.Wireguard.setDefaults(v.Provider.Name)
 	v.PMTUD.setDefaults()
+	v.UpCommand = gosettings.DefaultPointer(v.UpCommand, "")
+	v.DownCommand = gosettings.DefaultPointer(v.DownCommand, "")
 }
 
 func (v VPN) String() string {
@@ -89,13 +116,23 @@ func (v VPN) toLinesNode() (node *gotree.Node) {
 
 	node.AppendNode(v.Provider.toLinesNode())
 
-	if v.Type == vpn.OpenVPN {
+	switch v.Type {
+	case vpn.AmneziaWg:
+		node.AppendNode(v.AmneziaWg.toLinesNode())
+	case vpn.OpenVPN:
 		node.AppendNode(v.OpenVPN.toLinesNode())
-	} else {
+	case vpn.Wireguard:
 		node.AppendNode(v.Wireguard.toLinesNode())
 	}
 	node.AppendNode(v.PMTUD.toLinesNode())
 
+	if *v.UpCommand != "" {
+		node.Appendf("Up command: %s", *v.UpCommand)
+	}
+	if *v.DownCommand != "" {
+		node.Appendf("Down command: %s", *v.DownCommand)
+	}
+
 	return node
 }
 
@@ -107,12 +144,18 @@ func (v *VPN) read(r *reader.Reader) (err error) {
 		return fmt.Errorf("VPN provider: %w", err)
 	}
 
+	err = v.AmneziaWg.read(r)
+	if err != nil {
+		return fmt.Errorf("AmneziaWG: %w", err)
+	}
+
 	err = v.OpenVPN.read(r)
 	if err != nil {
 		return fmt.Errorf("OpenVPN: %w", err)
 	}
 
-	err = v.Wireguard.read(r)
+	const amneziawg = false
+	err = v.Wireguard.read(r, amneziawg)
 	if err != nil {
 		return fmt.Errorf("wireguard: %w", err)
 	}
@@ -122,5 +165,9 @@ func (v *VPN) read(r *reader.Reader) (err error) {
 		return fmt.Errorf("PMTUD: %w", err)
 	}
 
+	v.UpCommand = r.Get("VPN_UP_COMMAND", reader.ForceLowercase(false))
+
+	v.DownCommand = r.Get("VPN_DOWN_COMMAND", reader.ForceLowercase(false))
+
 	return nil
 }

internal/configuration/settings/wireguard.go

@@ -1,13 +1,13 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"net/netip"
 	"regexp"
 	"strings"
 	"time"
 
-	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
 	"github.com/qdm12/gluetun/internal/constants/providers"
 	"github.com/qdm12/gosettings"
 	"github.com/qdm12/gosettings/reader"
@@ -46,31 +46,23 @@ type Wireguard struct {
 	// It defaults to "auto" and cannot be the empty string
 	// in the internal state.
 	Implementation string `json:"implementation"`
+	// GSO enables wireguard-go's GRO/GSO batched TUN I/O by creating
+	// the WireGuard TUN device with IFF_VNET_HDR. It should be disabled
+	// on kernels (e.g. certain NAS devices) that claim IFF_VNET_HDR
+	// support but return EINVAL when wireguard-go writes GRO-coalesced
+	// packets with virtio_net_hdr structs under load.
+	// It defaults to true and cannot be nil in the internal state.
+	GSO *bool `json:"gso"`
 }
 
 var regexpInterfaceName = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)
 
 // Validate validates Wireguard settings.
-// It should only be ran if the VPN type chosen is Wireguard.
-func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error) {
-	if !helpers.IsOneOf(vpnProvider,
-		providers.Airvpn,
-		providers.Custom,
-		providers.Fastestvpn,
-		providers.Ivpn,
-		providers.Mullvad,
-		providers.Nordvpn,
-		providers.Protonvpn,
-		providers.Surfshark,
-		providers.Windscribe,
-	) {
-		// do not validate for VPN provider not supporting Wireguard
-		return nil
-	}
-
+// It should only be ran if the VPN type chosen is Wireguard or AmneziaWg.
+func (w Wireguard) validate(vpnProvider string, ipv6Supported, amneziawg bool) (err error) {
 	// Validate PrivateKey
 	if *w.PrivateKey == "" {
-		return fmt.Errorf("%w", ErrWireguardPrivateKeyNotSet)
+		return errors.New("private key is not set")
 	}
 	_, err = wgtypes.ParseKey(*w.PrivateKey)
 	if err != nil {
@@ -84,7 +76,7 @@ func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error)
 
 	if vpnProvider == providers.Airvpn {
 		if *w.PreSharedKey == "" {
-			return fmt.Errorf("%w", ErrWireguardPreSharedKeyNotSet)
+			return errors.New("pre-shared key is not set")
 		}
 	}
 
@@ -98,17 +90,15 @@ func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error)
 
 	// Validate Addresses
 	if len(w.Addresses) == 0 {
-		return fmt.Errorf("%w", ErrWireguardInterfaceAddressNotSet)
+		return errors.New("interface address is not set")
 	}
 	for i, ipNet := range w.Addresses {
 		if !ipNet.IsValid() {
-			return fmt.Errorf("%w: for address at index %d",
-				ErrWireguardInterfaceAddressNotSet, i)
+			return fmt.Errorf("interface address is not set: for address at index %d", i)
 		}
 
 		if !ipv6Supported && ipNet.Addr().Is6() {
-			return fmt.Errorf("%w: address %s",
-				ErrWireguardInterfaceAddressIPv6, ipNet.String())
+			return fmt.Errorf("interface address is IPv6 but IPv6 is not supported: address %s", ipNet.String())
 		}
 	}
 
@@ -116,29 +106,28 @@ func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error)
 	// WARNING: do not check for IPv6 networks in the allowed IPs,
 	// the wireguard code will take care to ignore it.
 	if len(w.AllowedIPs) == 0 {
-		return fmt.Errorf("%w", ErrWireguardAllowedIPsNotSet)
+		return errors.New("allowed IPs is not set")
 	}
 	for i, allowedIP := range w.AllowedIPs {
 		if !allowedIP.IsValid() {
-			return fmt.Errorf("%w: for allowed ip %d of %d",
-				ErrWireguardAllowedIPNotSet, i+1, len(w.AllowedIPs))
+			return fmt.Errorf("allowed IP is not set: for allowed ip %d of %d", i+1, len(w.AllowedIPs))
 		}
 	}
 
 	if *w.PersistentKeepaliveInterval < 0 {
-		return fmt.Errorf("%w: %s", ErrWireguardKeepAliveNegative,
-			*w.PersistentKeepaliveInterval)
+		return fmt.Errorf("persistent keep alive interval is negative: %s", *w.PersistentKeepaliveInterval)
 	}
 
 	// Validate interface
 	if !regexpInterfaceName.MatchString(w.Interface) {
-		return fmt.Errorf("%w: '%s' does not match regex '%s'",
-			ErrWireguardInterfaceNotValid, w.Interface, regexpInterfaceName)
+		return fmt.Errorf("interface name is not valid: '%s' does not match regex '%s'", w.Interface, regexpInterfaceName)
 	}
 
-	validImplementations := []string{"auto", "userspace", "kernelspace"}
-	if err := validate.IsOneOf(w.Implementation, validImplementations...); err != nil {
-		return fmt.Errorf("%w: %w", ErrWireguardImplementationNotValid, err)
+	if !amneziawg { // amneziawg should have its own Implementation field and ignore this one
+		validImplementations := []string{"auto", "userspace", "kernelspace"}
+		if err := validate.IsOneOf(w.Implementation, validImplementations...); err != nil {
+			return fmt.Errorf("implementation is not valid: %w", err)
+		}
 	}
 
 	return nil
@@ -154,6 +143,7 @@ func (w *Wireguard) copy() (copied Wireguard) {
 		Interface:                   w.Interface,
 		MTU:                         w.MTU,
 		Implementation:              w.Implementation,
+		GSO:                         gosettings.CopyPointer(w.GSO),
 	}
 }
 
@@ -167,6 +157,7 @@ func (w *Wireguard) overrideWith(other Wireguard) {
 	w.Interface = gosettings.OverrideWithComparable(w.Interface, other.Interface)
 	w.MTU = gosettings.OverrideWithComparable(w.MTU, other.MTU)
 	w.Implementation = gosettings.OverrideWithComparable(w.Implementation, other.Implementation)
+	w.GSO = gosettings.OverrideWithPointer(w.GSO, other.GSO)
 }
 
 func (w *Wireguard) setDefaults(vpnProvider string) {
@@ -191,6 +182,7 @@ func (w *Wireguard) setDefaults(vpnProvider string) {
 	w.Interface = gosettings.DefaultComparable(w.Interface, "wg0")
 	w.MTU = gosettings.DefaultPointer(w.MTU, 0)
 	w.Implementation = gosettings.DefaultComparable(w.Implementation, "auto")
+	w.GSO = gosettings.DefaultPointer(w.GSO, true)
 }
 
 func (w Wireguard) String() string {
@@ -235,24 +227,37 @@ func (w Wireguard) toLinesNode() (node *gotree.Node) {
 		node.Appendf("Implementation: %s", w.Implementation)
 	}
 
+	if !*w.GSO {
+		node.Append("GSO disabled")
+	}
+
 	return node
 }
 
-func (w *Wireguard) read(r *reader.Reader) (err error) {
-	w.PrivateKey = r.Get("WIREGUARD_PRIVATE_KEY", reader.ForceLowercase(false))
-	w.PreSharedKey = r.Get("WIREGUARD_PRESHARED_KEY", reader.ForceLowercase(false))
+func (w *Wireguard) read(r *reader.Reader, amneziaWG bool) (err error) {
+	prefix := "WIREGUARD"
+	if amneziaWG {
+		prefix = "AMNEZIAWG"
+	}
+	w.PrivateKey = r.Get(prefix+"_PRIVATE_KEY", reader.ForceLowercase(false))
+	w.PreSharedKey = r.Get(prefix+"_PRESHARED_KEY", reader.ForceLowercase(false))
 	w.Interface = r.String("VPN_INTERFACE",
-		reader.RetroKeys("WIREGUARD_INTERFACE"), reader.ForceLowercase(false))
-	w.Implementation = r.String("WIREGUARD_IMPLEMENTATION")
+		reader.RetroKeys(prefix+"_INTERFACE"), reader.ForceLowercase(false))
 
-	addressStrings := r.CSV("WIREGUARD_ADDRESSES", reader.RetroKeys("WIREGUARD_ADDRESS"))
+	if !amneziaWG {
+		w.Implementation = r.String("WIREGUARD_IMPLEMENTATION")
+	}
+
+	addressStrings := r.CSV(prefix+"_ADDRESSES", reader.RetroKeys(prefix+"_ADDRESS"))
 	// WARNING: do not initialize w.Addresses to an empty slice
 	// or the defaults for nordvpn will not work.
 	for _, addressString := range addressStrings {
-		if !strings.ContainsRune(addressString, '/') {
+		addressString = strings.TrimSpace(addressString)
+		if addressString == "" {
+			continue
+		} else if !strings.ContainsRune(addressString, '/') {
 			addressString += "/32"
 		}
-		addressString = strings.TrimSpace(addressString)
 		address, err := netip.ParsePrefix(addressString)
 		if err != nil {
 			return fmt.Errorf("parsing address: %w", err)
@@ -260,19 +265,25 @@ func (w *Wireguard) read(r *reader.Reader) (err error) {
 		w.Addresses = append(w.Addresses, address)
 	}
 
-	w.AllowedIPs, err = r.CSVNetipPrefixes("WIREGUARD_ALLOWED_IPS")
+	w.AllowedIPs, err = r.CSVNetipPrefixes(prefix + "_ALLOWED_IPS")
 	if err != nil {
 		return err // already wrapped
 	}
 
-	w.PersistentKeepaliveInterval, err = r.DurationPtr("WIREGUARD_PERSISTENT_KEEPALIVE_INTERVAL")
+	w.PersistentKeepaliveInterval, err = r.DurationPtr(prefix + "_PERSISTENT_KEEPALIVE_INTERVAL")
 	if err != nil {
 		return err
 	}
 
-	w.MTU, err = r.Uint32Ptr("WIREGUARD_MTU")
+	w.MTU, err = r.Uint32Ptr(prefix + "_MTU")
 	if err != nil {
 		return err
 	}
+
+	w.GSO, err = r.BoolPtr("WIREGUARD_GSO")
+	if err != nil {
+		return err
+	}
+
 	return nil
 }

internal/configuration/settings/wireguardselection.go

@@ -1,6 +1,7 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"net/netip"
 
@@ -44,7 +45,7 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 		// endpoint IP addresses are baked in
 	case providers.Custom:
 		if !w.EndpointIP.IsValid() || w.EndpointIP.IsUnspecified() {
-			return fmt.Errorf("%w", ErrWireguardEndpointIPNotSet)
+			return errors.New("endpoint IP is not set")
 		}
 	default: // Providers not supporting Wireguard
 	}
@@ -54,13 +55,13 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 	// EndpointPort is required
 	case providers.Custom:
 		if *w.EndpointPort == 0 {
-			return fmt.Errorf("%w", ErrWireguardEndpointPortNotSet)
+			return errors.New("endpoint port is not set")
 		}
 	// EndpointPort cannot be set
 	case providers.Fastestvpn, providers.Nordvpn,
 		providers.Protonvpn, providers.Surfshark:
 		if *w.EndpointPort != 0 {
-			return fmt.Errorf("%w", ErrWireguardEndpointPortSet)
+			return errors.New("endpoint port is set")
 		}
 	case providers.Airvpn, providers.Ivpn, providers.Mullvad, providers.Windscribe:
 		// EndpointPort is optional and can be 0
@@ -84,8 +85,7 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 		if err == nil {
 			break
 		}
-		return fmt.Errorf("%w: for VPN service provider %s: %w",
-			ErrWireguardEndpointPortNotAllowed, vpnProvider, err)
+		return fmt.Errorf("endpoint port is not allowed: for VPN service provider %s: %w", vpnProvider, err)
 	default: // Providers not supporting Wireguard
 	}
 
@@ -96,15 +96,14 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 		// public keys are baked in
 	case providers.Custom:
 		if w.PublicKey == "" {
-			return fmt.Errorf("%w", ErrWireguardPublicKeyNotSet)
+			return errors.New("public key is not set")
 		}
 	default: // Providers not supporting Wireguard
 	}
 	if w.PublicKey != "" {
 		_, err := wgtypes.ParseKey(w.PublicKey)
 		if err != nil {
-			return fmt.Errorf("%w: %s: %s",
-				ErrWireguardPublicKeyNotValid, w.PublicKey, err)
+			return fmt.Errorf("public key is not valid: %s: %s", w.PublicKey, err)
 		}
 	}
 
@@ -152,18 +151,22 @@ func (w WireguardSelection) toLinesNode() (node *gotree.Node) {
 	return node
 }
 
-func (w *WireguardSelection) read(r *reader.Reader) (err error) {
-	w.EndpointIP, err = r.NetipAddr("WIREGUARD_ENDPOINT_IP", reader.RetroKeys("VPN_ENDPOINT_IP"))
+func (w *WireguardSelection) read(r *reader.Reader, amneziaWG bool) (err error) {
+	prefix := "WIREGUARD"
+	if amneziaWG {
+		prefix = "AMNEZIAWG"
+	}
+	w.EndpointIP, err = r.NetipAddr(prefix+"_ENDPOINT_IP", reader.RetroKeys("VPN_ENDPOINT_IP"))
 	if err != nil {
 		return fmt.Errorf("%w - note this MUST be an IP address, "+
 			"see https://github.com/qdm12/gluetun/issues/788", err)
 	}
 
-	w.EndpointPort, err = r.Uint16Ptr("WIREGUARD_ENDPOINT_PORT", reader.RetroKeys("VPN_ENDPOINT_PORT"))
+	w.EndpointPort, err = r.Uint16Ptr(prefix+"_ENDPOINT_PORT", reader.RetroKeys("VPN_ENDPOINT_PORT"))
 	if err != nil {
 		return err
 	}
 
-	w.PublicKey = r.String("WIREGUARD_PUBLIC_KEY", reader.ForceLowercase(false))
+	w.PublicKey = r.String(prefix+"_PUBLIC_KEY", reader.ForceLowercase(false))
 	return nil
 }