FIREWALL_IMPLEMENTATION option

Dockerfile

@@ -165,6 +165,7 @@ ENV VPN_SERVICE_PROVIDER=pia \
     FIREWALL_VPN_INPUT_PORTS= \
     FIREWALL_INPUT_PORTS= \
     FIREWALL_OUTBOUND_SUBNETS= \
+    FIREWALL_IMPLEMENTATION=iptables \
     FIREWALL_DEBUG=off \
     # Logging
     LOG_LEVEL=info \

cmd/gluetun/main.go

@@ -226,8 +226,8 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 	if *allSettings.Firewall.Debug { // To remove in v4
 		firewallLogger.Patch(log.SetLevel(log.LevelDebug))
 	}
-	firewallConf, err := firewall.NewConfig(ctx, firewallLogger, cmder,
-		defaultRoutes, localNetworks)
+	firewallConf, err := firewall.NewConfig(ctx, allSettings.Firewall.Implementation,
+		firewallLogger, cmder, defaultRoutes, localNetworks)
 	if err != nil {
 		return err
 	}

internal/configuration/settings/firewall.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/netip"
 
+	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
 	"github.com/qdm12/gosettings"
 	"github.com/qdm12/gosettings/reader"
 	"github.com/qdm12/gotree"
@@ -16,6 +17,7 @@ type Firewall struct {
 	OutboundSubnets []netip.Prefix
 	Enabled         *bool
 	Debug           *bool
+	Implementation  string
 }
 
 func (f Firewall) validate() (err error) {
@@ -33,6 +35,10 @@ func (f Firewall) validate() (err error) {
 		}
 	}
 
+	if !helpers.IsOneOf(f.Implementation, "iptables", "nftables") {
+		return fmt.Errorf("firewall implementation %q must be either 'iptables' or 'nftables'", f.Implementation)
+	}
+
 	return nil
 }
 
@@ -52,6 +58,7 @@ func (f *Firewall) copy() (copied Firewall) {
 		OutboundSubnets: gosettings.CopySlice(f.OutboundSubnets),
 		Enabled:         gosettings.CopyPointer(f.Enabled),
 		Debug:           gosettings.CopyPointer(f.Debug),
+		Implementation:  f.Implementation,
 	}
 }
 
@@ -64,11 +71,13 @@ func (f *Firewall) overrideWith(other Firewall) {
 	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)
 }
 
 func (f *Firewall) setDefaults() {
 	f.Enabled = gosettings.DefaultPointer(f.Enabled, true)
 	f.Debug = gosettings.DefaultPointer(f.Debug, false)
+	f.Implementation = gosettings.DefaultComparable(f.Implementation, "iptables")
 }
 
 func (f Firewall) String() string {
@@ -83,6 +92,8 @@ func (f Firewall) toLinesNode() (node *gotree.Node) {
 		return node
 	}
 
+	node.Appendf("Implementation: %s", f.Implementation)
+
 	if *f.Debug {
 		node.Appendf("Debug mode: on")
 	}
@@ -138,5 +149,7 @@ func (f *Firewall) read(r *reader.Reader) (err error) {
 		return err
 	}
 
+	f.Implementation = r.String("FIREWALL_IMPLEMENTATION")
+
 	return nil
 }

internal/configuration/settings/settings_test.go

@@ -65,7 +65,8 @@ func Test_Settings_String(t *testing.T) {
 |       ├── Block ads: no
 |       └── Block surveillance: yes
 ├── Firewall settings:
-|   └── Enabled: yes
+|   ├── Enabled: yes
+|   └── Implementation: iptables
 ├── Log settings:
 |   └── Log level: INFO
 ├── Health settings:

internal/firewall/firewall.go

@@ -7,6 +7,7 @@ import (
 	"sync"
 
 	"github.com/qdm12/gluetun/internal/firewall/iptables"
+	"github.com/qdm12/gluetun/internal/firewall/nftables"
 	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gluetun/internal/routing"
 )
@@ -33,14 +34,25 @@ type Config struct {
 }
 
 // NewConfig creates a new Config instance and returns an error
-// if no iptables implementation is available.
-func NewConfig(ctx context.Context, logger Logger,
+// if no firewall implementation is available.
+func NewConfig(ctx context.Context, implementation string, logger Logger,
 	runner CmdRunner, defaultRoutes []routing.DefaultRoute,
 	localNetworks []routing.LocalNetwork,
 ) (config *Config, err error) {
-	impl, err := iptables.New(ctx, runner, logger)
-	if err != nil {
-		return nil, fmt.Errorf("creating iptables firewall: %w", err)
+	var impl firewallImpl
+	var customRulesPath string
+	switch implementation {
+	case "iptables":
+		impl, err = iptables.New(ctx, runner, logger)
+		if err != nil {
+			return nil, fmt.Errorf("creating iptables firewall: %w", err)
+		}
+		customRulesPath = "/iptables/post-rules.txt"
+	case "nftables":
+		impl = nftables.New(logger)
+		customRulesPath = "/gluetun/firewall/nftables/post-rules.txt"
+	default:
+		return nil, fmt.Errorf("unknown firewall implementation: %s", implementation)
 	}
 
 	return &Config{
@@ -51,6 +63,6 @@ func NewConfig(ctx context.Context, logger Logger,
 		defaultRoutes:   defaultRoutes,
 		localNetworks:   localNetworks,
 		impl:            impl,
-		customRulesPath: "/iptables/post-rules.txt",
+		customRulesPath: customRulesPath,
 	}, nil
 }

internal/firewall/interfaces.go

@@ -16,6 +16,7 @@ type Logger interface {
 	Debug(s string)
 	Info(s string)
 	Warn(s string)
+	Warnf(format string, args ...any)
 	Error(s string)
 }