Routing improvements (#268)

- Fixes #82 
- Remove `EXTRA_SUBNETS`
- Remove no longer needed iptables rules
- Reduce routing interface arity
- Routing setup is done in main.go instead of in the firewall
- Routing setup gets reverted at shutdown

Dockerfile

@@ -89,7 +89,6 @@ ENV VPNSP=pia \
     DNS_KEEP_NAMESERVER=off \
     # Firewall
     FIREWALL=on \
-    EXTRA_SUBNETS= \
     FIREWALL_VPN_INPUT_PORTS= \
     FIREWALL_INPUT_PORTS= \
     FIREWALL_DEBUG=off \

README.md

@@ -69,8 +69,8 @@ iptables, DNS over TLS, ShadowSocks and Tinyproxy*
     Note that you can:
 
     - Change the many [environment variables](#environment-variables) available
-    - Use `-p 8888:8888/tcp` to access the HTTP web proxy (and put your LAN in `EXTRA_SUBNETS` environment variable, in example `192.168.1.0/24`)
-    - Use `-p 8388:8388/tcp -p 8388:8388/udp` to access the Shadowsocks proxy (and put your LAN in `EXTRA_SUBNETS` environment variable, in example `192.168.1.0/24`)
+    - Use `-p 8888:8888/tcp` to access the HTTP web proxy
+    - Use `-p 8388:8388/tcp -p 8388:8388/udp` to access the Shadowsocks proxy
     - Use `-p 8000:8000/tcp` to access the [HTTP control server](#HTTP-control-server) built-in
 
     **If you encounter an issue with the tun device not being available, see [the FAQ](https://github.com/qdm12/gluetun/blob/master/doc/faq.md#how-to-fix-openvpn-failing-to-start)**
@@ -230,7 +230,6 @@ That one is important if you want to connect to the container from your LAN for
 | Variable | Default | Choices | Description |
 | --- | --- | --- | --- |
 | `FIREWALL` | `on` | `on` or `off` | Turn on or off the container built-in firewall. You should use it for **debugging purposes** only. |
-| `EXTRA_SUBNETS` | | i.e. `192.168.1.0/24,192.168.10.121,10.0.0.5/28` | Comma separated subnets allowed in the container firewall |
 | `FIREWALL_VPN_INPUT_PORTS` | | i.e. `1000,8080` | Comma separated list of ports to allow from the VPN server side (useful for **vyprvpn** port forwarding) |
 | `FIREWALL_INPUT_PORTS` | | i.e. `1000,8000` | Comma separated list of ports to allow through the default interface. This seems needed for Kubernetes sidecars. |
 | `FIREWALL_DEBUG` | `off` | `on` or `off` | Prints every firewall related command. You should use it for **debugging purposes** only. |
@@ -304,7 +303,6 @@ There are various ways to achieve this, depending on your use case.
     1. Setup a HTTP proxy client, such as [SwitchyOmega for Chrome](https://chrome.google.com/webstore/detail/proxy-switchyomega/padekgcemlokbadohgkifijomclgjgif?hl=en)
     1. Ensure the Gluetun container is launched with:
         - port `8888` published `-p 8888:8888/tcp`
-        - your LAN subnet, i.e. `192.168.1.0/24`, set as `-e EXTRA_SUBNETS=192.168.1.0/24`
     1. With your HTTP proxy client, connect to the Docker host (i.e. `192.168.1.10`) on port `8888`. You need to enter your credentials if you set them with `TINYPROXY_USER` and `TINYPROXY_PASSWORD`.
     1. If you set `TINYPROXY_LOG` to `Info`, more information will be logged in the Docker logs
 
@@ -319,7 +317,6 @@ There are various ways to achieve this, depending on your use case.
             - Android: Shadowsocks by Max Lv
     1. Ensure the Gluetun container is launched with:
         - port `8388` published `-p 8388:8388/tcp -p 8388:8388/udp`
-        - your LAN subnet, i.e. `192.168.1.0/24`, set as `-e EXTRA_SUBNETS=192.168.1.0/24`
     1. With your Shadowsocks proxy client
         - Enter the Docker host (i.e. `192.168.1.10`) as the server IP
         - Enter port TCP (and UDP, if available) `8388` as the server port

cmd/gluetun/main.go

@@ -150,6 +150,16 @@ func _main(background context.Context, args []string) int { //nolint:gocognit,go
 
 	firewallConf.SetNetworkInformation(defaultInterface, defaultGateway, localSubnet)
 
+	if err := routingConf.Setup(); err != nil {
+		logger.Error(err)
+		return 1
+	}
+	defer func() {
+		if err := routingConf.TearDown(); err != nil {
+			logger.Error(err)
+		}
+	}()
+
 	if err := ovpnConf.CheckTUN(); err != nil {
 		logger.Warn(err)
 		err = ovpnConf.CreateTUN()
@@ -173,12 +183,6 @@ func _main(background context.Context, args []string) int { //nolint:gocognit,go
 		}
 	}
 
-	err = firewallConf.SetAllowedSubnets(ctx, allSettings.Firewall.AllowedSubnets)
-	if err != nil {
-		logger.Error(err)
-		return 1
-	}
-
 	for _, vpnPort := range allSettings.Firewall.VPNInputPorts {
 		err = firewallConf.SetAllowedPort(ctx, vpnPort, string(constants.TUN))
 		if err != nil {
@@ -193,7 +197,7 @@ func _main(background context.Context, args []string) int { //nolint:gocognit,go
 			logger.Error(err)
 			return 1
 		}
-	}
+	} // TODO move inside firewall?
 
 	wg := &sync.WaitGroup{}
 

docker-compose.yml

@@ -35,7 +35,4 @@ services:
 
       # Mullvad only
       - COUNTRY=Sweden
-
-      # Allow for example your LAN, set to: 192.168.1.0/24
-      - EXTRA_SUBNETS=
     restart: always

internal/firewall/enable.go

@@ -93,26 +93,12 @@ func (c *configurator) enable(ctx context.Context) (err error) {
 	if err = c.acceptOutputThroughInterface(ctx, string(constants.TUN), remove); err != nil {
 		return fmt.Errorf("cannot enable firewall: %w", err)
 	}
-	if err := c.acceptInputFromSubnetToSubnet(ctx, "*", c.localSubnet, c.localSubnet, remove); err != nil {
+
+	// Allows packets from any IP address to go through eth0 / local network
+	// to reach Gluetun.
+	if err := c.acceptInputToSubnet(ctx, c.defaultInterface, c.localSubnet, remove); err != nil {
 		return fmt.Errorf("cannot enable firewall: %w", err)
 	}
-	if err := c.acceptOutputFromSubnetToSubnet(ctx, "*", c.localSubnet, c.localSubnet, remove); err != nil {
-		return fmt.Errorf("cannot enable firewall: %w", err)
-	}
-	for _, subnet := range c.allowedSubnets {
-		if err := c.acceptInputFromSubnetToSubnet(ctx, c.defaultInterface, subnet, c.localSubnet, remove); err != nil {
-			return fmt.Errorf("cannot enable firewall: %w", err)
-		}
-		if err := c.acceptOutputFromSubnetToSubnet(ctx, c.defaultInterface, c.localSubnet, subnet, remove); err != nil {
-			return fmt.Errorf("cannot enable firewall: %w", err)
-		}
-	}
-	// Re-ensure all routes exist
-	for _, subnet := range c.allowedSubnets {
-		if err := c.routing.AddRouteVia(subnet, c.defaultGateway, c.defaultInterface); err != nil {
-			return fmt.Errorf("cannot enable firewall: %w", err)
-		}
-	}
 
 	for port, intf := range c.allowedInputPorts {
 		if err := c.acceptInputToPort(ctx, intf, port, remove); err != nil {

internal/firewall/firewall.go

@@ -17,7 +17,6 @@ type Configurator interface {
 	Version(ctx context.Context) (string, error)
 	SetEnabled(ctx context.Context, enabled bool) (err error)
 	SetVPNConnection(ctx context.Context, connection models.OpenVPNConnection) (err error)
-	SetAllowedSubnets(ctx context.Context, subnets []net.IPNet) (err error)
 	SetAllowedPort(ctx context.Context, port uint16, intf string) (err error)
 	RemoveAllowedPort(ctx context.Context, port uint16) (err error)
 	SetDebug()
@@ -40,7 +39,6 @@ type configurator struct { //nolint:maligned
 	// State
 	enabled           bool
 	vpnConnection     models.OpenVPNConnection
-	allowedSubnets    []net.IPNet
 	allowedInputPorts map[uint16]string // port to interface mapping
 	stateMutex        sync.Mutex
 }

internal/firewall/iptables.go

@@ -94,6 +94,16 @@ func (c *configurator) acceptInputThroughInterface(ctx context.Context, intf str
 	))
 }
 
+func (c *configurator) acceptInputToSubnet(ctx context.Context, intf string, destination net.IPNet, remove bool) error {
+	interfaceFlag := "-i " + intf
+	if intf == "*" { // all interfaces
+		interfaceFlag = ""
+	}
+	return c.runIptablesInstruction(ctx, fmt.Sprintf(
+		"%s INPUT %s -d %s -j ACCEPT", appendOrDelete(remove), interfaceFlag, destination.String(),
+	))
+}
+
 func (c *configurator) acceptOutputThroughInterface(ctx context.Context, intf string, remove bool) error {
 	return c.runIptablesInstruction(ctx, fmt.Sprintf(
 		"%s OUTPUT -o %s -j ACCEPT", appendOrDelete(remove), intf,
@@ -114,31 +124,6 @@ func (c *configurator) acceptOutputTrafficToVPN(ctx context.Context,
 			appendOrDelete(remove), connection.IP, defaultInterface, connection.Protocol, connection.Protocol, connection.Port))
 }
 
-func (c *configurator) acceptInputFromSubnetToSubnet(ctx context.Context,
-	intf string, sourceSubnet, destinationSubnet net.IPNet, remove bool) error {
-	interfaceFlag := "-i " + intf
-	if intf == "*" { // all interfaces
-		interfaceFlag = ""
-	}
-	return c.runIptablesInstruction(ctx, fmt.Sprintf(
-		"%s INPUT %s -s %s -d %s -j ACCEPT",
-		appendOrDelete(remove), interfaceFlag, sourceSubnet.String(), destinationSubnet.String(),
-	))
-}
-
-// Thanks to @npawelek.
-func (c *configurator) acceptOutputFromSubnetToSubnet(ctx context.Context,
-	intf string, sourceSubnet, destinationSubnet net.IPNet, remove bool) error {
-	interfaceFlag := "-o " + intf
-	if intf == "*" { // all interfaces
-		interfaceFlag = ""
-	}
-	return c.runIptablesInstruction(ctx, fmt.Sprintf(
-		"%s OUTPUT %s -s %s -d %s -j ACCEPT",
-		appendOrDelete(remove), interfaceFlag, sourceSubnet.String(), destinationSubnet.String(),
-	))
-}
-
 // Used for port forwarding, with intf set to tun.
 func (c *configurator) acceptInputToPort(ctx context.Context, intf string, port uint16, remove bool) error {
 	interfaceFlag := "-i " + intf

internal/firewall/subnets.go

@@ -1,144 +0,0 @@
-package firewall
-
-import (
-	"context"
-	"fmt"
-	"net"
-)
-
-func (c *configurator) SetAllowedSubnets(ctx context.Context, subnets []net.IPNet) (err error) {
-	c.stateMutex.Lock()
-	defer c.stateMutex.Unlock()
-
-	if !c.enabled {
-		c.logger.Info("firewall disabled, only updating allowed subnets internal list and updating routes")
-		c.updateSubnetRoutes(c.allowedSubnets, subnets)
-		c.allowedSubnets = make([]net.IPNet, len(subnets))
-		copy(c.allowedSubnets, subnets)
-		return nil
-	}
-
-	c.logger.Info("setting allowed subnets through firewall...")
-
-	subnetsToAdd := findSubnetsToAdd(c.allowedSubnets, subnets)
-	subnetsToRemove := findSubnetsToRemove(c.allowedSubnets, subnets)
-	if len(subnetsToAdd) == 0 && len(subnetsToRemove) == 0 {
-		return nil
-	}
-
-	c.removeSubnets(ctx, subnetsToRemove, c.defaultInterface, c.localSubnet)
-	if err := c.addSubnets(ctx, subnetsToAdd, c.defaultInterface, c.defaultGateway, c.localSubnet); err != nil {
-		return fmt.Errorf("cannot set allowed subnets through firewall: %w", err)
-	}
-
-	return nil
-}
-
-func findSubnetsToAdd(oldSubnets, newSubnets []net.IPNet) (subnetsToAdd []net.IPNet) {
-	for _, newSubnet := range newSubnets {
-		found := false
-		for _, oldSubnet := range oldSubnets {
-			if subnetsAreEqual(oldSubnet, newSubnet) {
-				found = true
-				break
-			}
-		}
-		if !found {
-			subnetsToAdd = append(subnetsToAdd, newSubnet)
-		}
-	}
-	return subnetsToAdd
-}
-
-func findSubnetsToRemove(oldSubnets, newSubnets []net.IPNet) (subnetsToRemove []net.IPNet) {
-	for _, oldSubnet := range oldSubnets {
-		found := false
-		for _, newSubnet := range newSubnets {
-			if subnetsAreEqual(oldSubnet, newSubnet) {
-				found = true
-				break
-			}
-		}
-		if !found {
-			subnetsToRemove = append(subnetsToRemove, oldSubnet)
-		}
-	}
-	return subnetsToRemove
-}
-
-func subnetsAreEqual(a, b net.IPNet) bool {
-	return a.IP.Equal(b.IP) && a.Mask.String() == b.Mask.String()
-}
-
-func removeSubnetFromSubnets(subnets []net.IPNet, subnet net.IPNet) []net.IPNet {
-	L := len(subnets)
-	for i := range subnets {
-		if subnetsAreEqual(subnet, subnets[i]) {
-			subnets[i] = subnets[L-1]
-			subnets = subnets[:L-1]
-			break
-		}
-	}
-	return subnets
-}
-
-func (c *configurator) removeSubnets(ctx context.Context, subnets []net.IPNet, defaultInterface string,
-	localSubnet net.IPNet) {
-	const remove = true
-	for _, subnet := range subnets {
-		failed := false
-		if err := c.acceptInputFromSubnetToSubnet(ctx, defaultInterface, subnet, localSubnet, remove); err != nil {
-			failed = true
-			c.logger.Error("cannot remove outdated allowed subnet through firewall: %s", err)
-		}
-		if err := c.acceptOutputFromSubnetToSubnet(ctx, defaultInterface, subnet, localSubnet, remove); err != nil {
-			failed = true
-			c.logger.Error("cannot remove outdated allowed subnet through firewall: %s", err)
-		}
-		if err := c.routing.DeleteRouteVia(subnet); err != nil {
-			failed = true
-			c.logger.Error("cannot remove outdated allowed subnet route: %s", err)
-		}
-		if failed {
-			continue
-		}
-		c.allowedSubnets = removeSubnetFromSubnets(c.allowedSubnets, subnet)
-	}
-}
-
-func (c *configurator) addSubnets(ctx context.Context, subnets []net.IPNet, defaultInterface string,
-	defaultGateway net.IP, localSubnet net.IPNet) error {
-	const remove = false
-	for _, subnet := range subnets {
-		if err := c.acceptInputFromSubnetToSubnet(ctx, defaultInterface, subnet, localSubnet, remove); err != nil {
-			return fmt.Errorf("cannot add allowed subnet through firewall: %w", err)
-		}
-		if err := c.acceptOutputFromSubnetToSubnet(ctx, defaultInterface, localSubnet, subnet, remove); err != nil {
-			return fmt.Errorf("cannot add allowed subnet through firewall: %w", err)
-		}
-		if err := c.routing.AddRouteVia(subnet, defaultGateway, defaultInterface); err != nil {
-			return fmt.Errorf("cannot add route for allowed subnet: %w", err)
-		}
-		c.allowedSubnets = append(c.allowedSubnets, subnet)
-	}
-	return nil
-}
-
-// updateSubnetRoutes does not return an error in order to try to run as many route commands as possible.
-func (c *configurator) updateSubnetRoutes(oldSubnets, newSubnets []net.IPNet) {
-	subnetsToAdd := findSubnetsToAdd(oldSubnets, newSubnets)
-	subnetsToRemove := findSubnetsToRemove(oldSubnets, newSubnets)
-	if len(subnetsToAdd) == 0 && len(subnetsToRemove) == 0 {
-		return
-	}
-	for _, subnet := range subnetsToRemove {
-		if err := c.routing.DeleteRouteVia(subnet); err != nil {
-			c.logger.Error("cannot remove outdated route for subnet: %s", err)
-		}
-	}
-	for _, subnet := range subnetsToAdd {
-		if err := c.routing.AddRouteVia(subnet, c.defaultGateway, c.defaultInterface); err != nil {
-			c.logger.Error("cannot add route for subnet: %s", err)
-		}
-	}
-}

internal/params/firewall.go

@@ -2,7 +2,6 @@ package params
 
 import (
 	"fmt"
-	"net"
 	"strconv"
 	"strings"
 
@@ -14,28 +13,6 @@ func (r *reader) GetFirewall() (enabled bool, err error) {
 	return r.envParams.GetOnOff("FIREWALL", libparams.Default("on"))
 }
 
-// GetExtraSubnets obtains the CIDR subnets from the comma separated list of the
-// environment variable EXTRA_SUBNETS.
-func (r *reader) GetExtraSubnets() (extraSubnets []net.IPNet, err error) {
-	s, err := r.envParams.GetEnv("EXTRA_SUBNETS")
-	if err != nil {
-		return nil, err
-	} else if s == "" {
-		return nil, nil
-	}
-	subnets := strings.Split(s, ",")
-	for _, subnet := range subnets {
-		_, cidr, err := net.ParseCIDR(subnet)
-		if err != nil {
-			return nil, fmt.Errorf("could not parse subnet %q from environment variable with key EXTRA_SUBNETS: %w", subnet, err)
-		} else if cidr == nil {
-			return nil, fmt.Errorf("parsing subnet %q resulted in a nil CIDR", subnet)
-		}
-		extraSubnets = append(extraSubnets, *cidr)
-	}
-	return extraSubnets, nil
-}
-
 // GetAllowedVPNInputPorts obtains a list of input ports to allow from the
 // VPN server side in the firewall, from the environment variable FIREWALL_VPN_INPUT_PORTS.
 func (r *reader) GetVPNInputPorts() (ports []uint16, err error) {

internal/params/params.go

@@ -41,7 +41,6 @@ type Reader interface {
 
 	// Firewall getters
 	GetFirewall() (enabled bool, err error)
-	GetExtraSubnets() (extraSubnets []net.IPNet, err error)
 	GetVPNInputPorts() (ports []uint16, err error)
 	GetInputPorts() (ports []uint16, err error)
 	GetFirewallDebug() (debug bool, err error)

internal/routing/enable.go

@@ -0,0 +1,62 @@
+package routing
+
+import (
+	"fmt"
+	"net"
+)
+
+var (
+	ErrSetup    = fmt.Errorf("cannot setup routing")
+	ErrTeardown = fmt.Errorf("cannot teardown routing")
+)
+
+const (
+	table    = 200
+	priority = 100
+)
+
+func (r *routing) Setup() (err error) {
+	defaultIP, err := r.defaultIP()
+	if err != nil {
+		return fmt.Errorf("%s: %w", ErrSetup, err)
+	}
+	defaultInterfaceName, defaultGateway, err := r.DefaultRoute()
+	if err != nil {
+		return fmt.Errorf("%s: %w", ErrSetup, err)
+	}
+
+	defer func() {
+		if err == nil {
+			return
+		}
+		if err := r.TearDown(); err != nil {
+			r.logger.Error(err)
+		}
+	}()
+	if err := r.addIPRule(defaultIP, table, priority); err != nil {
+		return fmt.Errorf("%s: %w", ErrSetup, err)
+	}
+	if err := r.addRouteVia(net.IPNet{}, defaultGateway, defaultInterfaceName, table); err != nil {
+		return fmt.Errorf("%s: %w", ErrSetup, err)
+	}
+	return nil
+}
+
+func (r *routing) TearDown() error {
+	defaultIP, err := r.defaultIP()
+	if err != nil {
+		return fmt.Errorf("%s: %w", ErrTeardown, err)
+	}
+	defaultInterfaceName, defaultGateway, err := r.DefaultRoute()
+	if err != nil {
+		return fmt.Errorf("%s: %w", ErrTeardown, err)
+	}
+
+	if err := r.deleteRouteVia(net.IPNet{}, defaultGateway, defaultInterfaceName, table); err != nil {
+		return fmt.Errorf("%s: %w", ErrTeardown, err)
+	}
+	if err := r.deleteIPRule(defaultIP, table, priority); err != nil {
+		return fmt.Errorf("%s: %w", ErrTeardown, err)
+	}
+	return nil
+}

internal/routing/mutate.go

@@ -1,17 +1,18 @@
 package routing
 
 import (
+	"bytes"
 	"fmt"
 	"net"
 
 	"github.com/vishvananda/netlink"
 )
 
-func (r *routing) AddRouteVia(destination net.IPNet, gateway net.IP, iface string) error {
+func (r *routing) addRouteVia(destination net.IPNet, gateway net.IP, iface string, table int) error {
 	destinationStr := destination.String()
 	r.logger.Info("adding route for %s", destinationStr)
 	if r.debug {
-		fmt.Printf("ip route add %s via %s dev %s\n", destinationStr, gateway, iface)
+		fmt.Printf("ip route replace %s via %s dev %s table %d\n", destinationStr, gateway, iface, table)
 	}
 
 	link, err := netlink.LinkByName(iface)
@@ -22,6 +23,7 @@ func (r *routing) AddRouteVia(destination net.IPNet, gateway net.IP, iface strin
 		Dst:       &destination,
 		Gw:        gateway,
 		LinkIndex: link.Attrs().Index,
+		Table:     table,
 	}
 	if err := netlink.RouteReplace(&route); err != nil {
 		return fmt.Errorf("cannot add route for %s: %w", destinationStr, err)
@@ -29,17 +31,80 @@ func (r *routing) AddRouteVia(destination net.IPNet, gateway net.IP, iface strin
 	return nil
 }
 
-func (r *routing) DeleteRouteVia(destination net.IPNet) (err error) {
+func (r *routing) deleteRouteVia(destination net.IPNet, gateway net.IP, iface string, table int) (err error) {
 	destinationStr := destination.String()
 	r.logger.Info("deleting route for %s", destinationStr)
 	if r.debug {
-		fmt.Printf("ip route del %s\n", destinationStr)
+		fmt.Printf("ip route delete %s via %s dev %s table %d\n", destinationStr, gateway, iface, table)
+	}
+
+	link, err := netlink.LinkByName(iface)
+	if err != nil {
+		return fmt.Errorf("cannot delete route for %s: %w", destinationStr, err)
 	}
 	route := netlink.Route{
 		Dst:       &destination,
+		Gw:        gateway,
+		LinkIndex: link.Attrs().Index,
+		Table:     table,
 	}
 	if err := netlink.RouteDel(&route); err != nil {
 		return fmt.Errorf("cannot delete route for %s: %w", destinationStr, err)
 	}
 	return nil
 }
+
+func (r *routing) addIPRule(src net.IP, table, priority int) error {
+	if r.debug {
+		fmt.Printf("ip rule add from %s lookup %d pref %d\n",
+			src, table, priority)
+	}
+
+	rule := netlink.NewRule()
+	rule.Src = netlink.NewIPNet(src)
+	rule.Priority = priority
+	rule.Table = table
+
+	rules, err := netlink.RuleList(netlink.FAMILY_ALL)
+	if err != nil {
+		return fmt.Errorf("cannot add ip rule: %w", err)
+	}
+	for _, existingRule := range rules {
+		if existingRule.Src != nil &&
+			existingRule.Src.IP.Equal(rule.Src.IP) &&
+			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
+			existingRule.Priority == rule.Priority &&
+			existingRule.Table == rule.Table {
+			return nil // already exists
+		}
+	}
+
+	return netlink.RuleAdd(rule)
+}
+
+func (r *routing) deleteIPRule(src net.IP, table, priority int) error {
+	if r.debug {
+		fmt.Printf("ip rule del from %s lookup %d pref %d\n",
+			src, table, priority)
+	}
+
+	rule := netlink.NewRule()
+	rule.Src = netlink.NewIPNet(src)
+	rule.Priority = priority
+	rule.Table = table
+
+	rules, err := netlink.RuleList(netlink.FAMILY_ALL)
+	if err != nil {
+		return fmt.Errorf("cannot add ip rule: %w", err)
+	}
+	for _, existingRule := range rules {
+		if existingRule.Src != nil &&
+			existingRule.Src.IP.Equal(rule.Src.IP) &&
+			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
+			existingRule.Priority == rule.Priority &&
+			existingRule.Table == rule.Table {
+			return netlink.RuleDel(rule)
+		}
+	}
+	return nil
+}

internal/routing/reader.go

@@ -31,6 +31,30 @@ func (r *routing) DefaultRoute() (defaultInterface string, defaultGateway net.IP
 	return "", nil, fmt.Errorf("cannot find default route in %d routes", len(routes))
 }
 
+func (r *routing) defaultIP() (ip net.IP, err error) {
+	routes, err := netlink.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return nil, fmt.Errorf("cannot get default IP address: %w", err)
+	}
+
+	defaultLinkName := ""
+	for _, route := range routes {
+		if route.Dst == nil {
+			linkIndex := route.LinkIndex
+			link, err := netlink.LinkByIndex(linkIndex)
+			if err != nil {
+				return nil, fmt.Errorf("cannot get default IP address: %w", err)
+			}
+			defaultLinkName = link.Attrs().Name
+		}
+	}
+	if len(defaultLinkName) == 0 {
+		return nil, fmt.Errorf("cannot find default link name in %d routes", len(routes))
+	}
+
+	return r.assignedIP(defaultLinkName)
+}
+
 func (r *routing) LocalSubnet() (defaultSubnet net.IPNet, err error) {
 	routes, err := netlink.RouteList(nil, netlink.FAMILY_ALL)
 	if err != nil {
@@ -60,6 +84,26 @@ func (r *routing) LocalSubnet() (defaultSubnet net.IPNet, err error) {
 	return defaultSubnet, fmt.Errorf("cannot find default subnet in %d routes", len(routes))
 }
 
+func (r *routing) assignedIP(interfaceName string) (ip net.IP, err error) {
+	iface, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return nil, err
+	}
+	addresses, err := iface.Addrs()
+	if err != nil {
+		return nil, err
+	}
+	for _, address := range addresses {
+		switch value := address.(type) {
+		case *net.IPAddr:
+			return value.IP, nil
+		case *net.IPNet:
+			return value.IP, nil
+		}
+	}
+	return nil, fmt.Errorf("IP address not found in addresses of interface %s", interfaceName)
+}
+
 func (r *routing) VPNDestinationIP() (ip net.IP, err error) {
 	routes, err := netlink.RouteList(nil, netlink.FAMILY_ALL)
 	if err != nil {

internal/routing/routing.go

@@ -7,8 +7,8 @@ import (
 )
 
 type Routing interface {
-	AddRouteVia(destination net.IPNet, gateway net.IP, iface string) error
-	DeleteRouteVia(destination net.IPNet) (err error)
+	Setup() (err error)
+	TearDown() error
 	DefaultRoute() (defaultInterface string, defaultGateway net.IP, err error)
 	LocalSubnet() (defaultSubnet net.IPNet, err error)
 	VPNDestinationIP() (ip net.IP, err error)

internal/settings/firewall.go

@@ -2,7 +2,6 @@ package settings
 
 import (
 	"fmt"
-	"net"
 	"strings"
 
 	"github.com/qdm12/gluetun/internal/params"
@@ -10,7 +9,6 @@ import (
 
 // Firewall contains settings to customize the firewall operation.
 type Firewall struct {
-	AllowedSubnets []net.IPNet
 	VPNInputPorts []uint16
 	InputPorts    []uint16
 	Enabled       bool
@@ -18,10 +16,6 @@ type Firewall struct {
 }
 
 func (f *Firewall) String() string {
-	allowedSubnets := make([]string, len(f.AllowedSubnets))
-	for i := range f.AllowedSubnets {
-		allowedSubnets[i] = f.AllowedSubnets[i].String()
-	}
 	if !f.Enabled {
 		return "Firewall settings: disabled"
 	}
@@ -36,7 +30,6 @@ func (f *Firewall) String() string {
 
 	settingsList := []string{
 		"Firewall settings:",
-		"Allowed subnets: " + strings.Join(allowedSubnets, ", "),
 		"VPN input ports: " + strings.Join(vpnInputPorts, ", "),
 		"Input ports: " + strings.Join(inputPorts, ", "),
 	}
@@ -48,10 +41,6 @@ func (f *Firewall) String() string {
 
 // GetFirewallSettings obtains firewall settings from environment variables using the params package.
 func GetFirewallSettings(paramsReader params.Reader) (settings Firewall, err error) {
-	settings.AllowedSubnets, err = paramsReader.GetExtraSubnets()
-	if err != nil {
-		return settings, err
-	}
 	settings.VPNInputPorts, err = paramsReader.GetVPNInputPorts()
 	if err != nil {
 		return settings, err