fix: set accept_ra=2 to fix missing ipv6 address on WAN interface if necessary (#504)

control/control_plane.go

@@ -208,6 +208,7 @@ func NewControlPlane(
 	if len(global.LanInterface) > 0 {
 		if global.AutoConfigKernelParameter {
 			_ = SetIpv4forward("1")
+			_ = setForwarding("all", consts.IpVersionStr_6, "1")
 		}
 		global.LanInterface = common.Deduplicate(global.LanInterface)
 		for _, ifname := range global.LanInterface {
@@ -227,6 +228,19 @@ func NewControlPlane(
 			}
 		}
 		for _, ifname := range global.WanInterface {
+			if len(global.LanInterface) > 0 {
+				// FIXME: Code is not elegant here.
+				// bindLan setting conf.ipv6.all.forwarding=1 suppresses accept_ra=1,
+				// thus we set it 2 as a workaround.
+				// See https://sysctl-explorer.net/net/ipv6/accept_ra/ for more information.
+				if global.AutoConfigKernelParameter {
+					acceptRa := sysctl.Keyf("net.ipv6.conf.%v.accept_ra", ifname)
+					val, _ := acceptRa.Get()
+					if val == "1" {
+						_ = acceptRa.Set("2", false)
+					}
+				}
+			}
 			if err = core.bindWan(ifname, global.AutoConfigKernelParameter); err != nil {
 				return nil, fmt.Errorf("bindWan: %v: %w", ifname, err)
 			}

control/control_plane_core.go

@@ -247,7 +247,6 @@ func (c *controlPlaneCore) bindLan(ifname string, autoConfigKernelParameter bool
 	if autoConfigKernelParameter {
 		SetSendRedirects(ifname, "0")
 		SetForwarding(ifname, "1")
-		setForwarding("all", consts.IpVersionStr_6, "1")
 	}
 	if err := c._bindLan(ifname); err != nil {
 		var notFoundErr netlink.LinkNotFoundError

control/netns_utils.go

@@ -281,11 +281,11 @@ func (ns *DaeNetns) setupNetns() (err error) {
 
 func (ns *DaeNetns) setupSysctl() (err error) {
 	// sysctl net.ipv6.conf.dae0.disable_ipv6=0
-	if err = sysctl.Set(fmt.Sprintf("net.ipv6.conf.%s.disable_ipv6", HostVethName), "0", true); err != nil {
+	if err = sysctl.Keyf("net.ipv6.conf.%s.disable_ipv6", HostVethName).Set("0", true); err != nil {
 		return fmt.Errorf("failed to set disable_ipv6 for dae0: %v", err)
 	}
 	// sysctl net.ipv6.conf.dae0.forwarding=1
-	if err = sysctl.Set(fmt.Sprintf("net.ipv6.conf.%s.forwarding", HostVethName), "1", true); err != nil {
+	if err = sysctl.Keyf("net.ipv6.conf.%s.forwarding", HostVethName).Set("1", true); err != nil {
 		return fmt.Errorf("failed to set forwarding for dae0: %v", err)
 	}
 
@@ -295,12 +295,12 @@ func (ns *DaeNetns) setupSysctl() (err error) {
 	defer netns.Set(ns.hostNs)
 
 	// *_early_demux is not mandatory, but it's recommended to enable it for better performance
-	sysctl.Set("net.ipv4.tcp_early_demux", "1", false)
-	sysctl.Set("net.ipv4.ip_early_demux", "1", false)
+	sysctl.Keyf("net.ipv4.tcp_early_demux").Set("1", false)
+	sysctl.Keyf("net.ipv4.ip_early_demux").Set("1", false)
 
 	// (ip net e daens) sysctl net.ipv4.conf.dae0peer.accept_local=1
 	// This is to prevent kernel from dropping skb due to "martian source" check: https://elixir.bootlin.com/linux/v6.6/source/net/ipv4/fib_frontend.c#L381
-	if err = sysctl.Set(fmt.Sprintf("net.ipv4.conf.%s.accept_local", NsVethName), "1", false); err != nil {
+	if err = sysctl.Keyf("net.ipv4.conf.%s.accept_local", NsVethName).Set("1", false); err != nil {
 		return fmt.Errorf("failed to set accept_local for dae0peer: %v", err)
 	}
 	return

control/sysctl.go

@@ -1,6 +1,7 @@
 package control
 
 import (
+	"fmt"
 	"os"
 	"strings"
 	"sync"
@@ -76,8 +77,29 @@ func (s *SysctlManager) startWatch() {
 	}
 }
 
-func (s *SysctlManager) Set(key string, value string, watch bool) (err error) {
-	path := SysctlPrefixPath + strings.Replace(key, ".", "/", -1)
+type SysctlKey string
+
+func (s *SysctlManager) Keyf(format string, a ...any) SysctlKey {
+	return SysctlKey(SysctlPrefixPath + fmt.Sprintf(strings.ReplaceAll(format, ".", "/"), a...))
+}
+
+func (k SysctlKey) Get() (value string, err error) {
+	return sysctl.get(string(k))
+}
+
+func (k SysctlKey) Set(value string, watch bool) (err error) {
+	return sysctl.set(string(k), value, watch)
+}
+
+func (s *SysctlManager) get(path string) (value string, err error) {
+	val, err := os.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(val)), nil
+}
+
+func (s *SysctlManager) set(path string, value string, watch bool) (err error) {
 	if watch {
 		s.mux.Lock()
 		s.expectations[path] = value

docs/en/user-guide/kernel-parameters.md

@@ -10,7 +10,7 @@ For every LAN interfaces you want to proxy:
 ```shell
 export lan_ifname=docker0
 
-sudo tee /etc/sysctl.d/60-dae-$lan_ifname.conf << EOF
+sudo tee /etc/sysctl.d/60-dae-lan-$lan_ifname.conf << EOF
 net.ipv4.conf.$lan_ifname.forwarding = 1
 net.ipv6.conf.$lan_ifname.forwarding = 1
 net.ipv4.conf.$lan_ifname.send_redirects = 0
@@ -27,3 +27,20 @@ sudo sysctl --system
 ```
 
 Please modify `docker0` to your LAN interface.
+
+For your WAN interfaces that accept RA:
+
+```shell
+export wan_ifname=eth0
+
+if [ "$(cat /proc/sys/net/ipv6/conf/$wan_ifname/accept_ra)" == "1" ]; then
+    sudo tee /etc/sysctl.d/60-dae-wan-$wan_ifname.conf << EOF
+net.ipv6.conf.$wan_ifname.accept_ra = 2
+EOF
+    sudo sysctl --system
+fi
+```
+
+Please modify `eth0` to your WAN interface.
+
+Setting accept_ra to 2 if it is 1 because `net.ipv6.conf.all.forwarding = 1` will suppress it. See <https://sysctl-explorer.net/net/ipv6/accept_ra/> for more information.