# Configure transparent proxy for router in IPv6 only network

> Environment:
>
> Router: ASUS ac66u_b1
>
> OS: asus merlin 384.3
>
> Shadowsocks: shadowsocks-libev 3.1(can support udp relay)

1. Make sure router can connect to VPS via IPv6.

2. Install shadowsocks-libev on VPS, start ss-server with IPv6 enabled and `-u` (udp relay).

3. Install ss-redir on router(need to install entware first).

4. Start ss-redir on router with `-u`.

   ```
   nohup ss-redir -s [VPS's ipv6 address] -p [shadowsocks's port] -m [encrypt method] -k [password] -b 0.0.0.0 -l 1080 -u > /dev/null &
   ```

5. Enable TPROXY on router:

   ```bash
    modprobe ip_set
    modprobe ip_set_hash_net
    modprobe ip_set_hash_ip
    modprobe xt_set
    modprobe xt_TPROXY.ko
   ```

6. Configure iptables: (NOTE: Configurations below is used for IPv6 connection. If you use IPv4 connection, don't forget to set iptables to allow traffics to VPS, or network willl be unreachable)

   ```bash
   # TCP rules
   iptables -t nat -N SHADOWSOCKS_TCP
   # Uncomment line below on ipv4 environment
   # iptables -t nat -A SHADOWSOCKS -d [VPS's ipv4 address] -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 0.0.0.0/8 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 10.0.0.0/8 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 127.0.0.0/8 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 169.254.0.0/16 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 172.16.0.0/12 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 192.168.0.0/16 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 224.0.0.0/4 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -d 240.0.0.0/4 -j RETURN
   iptables -t nat -A SHADOWSOCKS_TCP -p tcp -j REDIRECT --to-ports 1080
   iptables -t nat -I PREROUTING 1 -p tcp -j SHADOWSOCKS_TCP
   iptables -t nat -I OUTPUT 1 -p tcp -j SHADOWSOCKS_TCP

   # UDP rules
   iptables -t mangle -N SHADOWSOCKS_UDP
   iptables -t mangle -N SHADOWSOCKS_MARK
   ip rule add fwmark 1 lookup 100
   ip route add local default dev lo table 100
   # Uncomment line below on ipv4 environment
   # iptables -t nat -A SHADOWSOCKS_MARK -d [VPS's ipv4 address] -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 0.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 10.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 127.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 169.254.0.0/16 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 172.16.0.0/12 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 192.168.0.0/16 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 224.0.0.0/4 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -d 240.0.0.0/4 -j RETURN
   # Uncomment line below on ipv4 environment
   # iptables -t nat -A SHADOWSOCKS_UDP -d [VPS's ipv4 address] -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 0.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 10.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 127.0.0.0/8 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 169.254.0.0/16 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 172.16.0.0/12 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 192.168.0.0/16 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 224.0.0.0/4 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_UDP -d 240.0.0.0/4 -j RETURN
   iptables -t mangle -A SHADOWSOCKS_MARK -p udp -d 8.8.8.8 --dport 53 -j MARK --set-mark 1
   iptables -t mangle -A SHADOWSOCKS_UDP -p udp --dport 53 -j TPROXY --on-port 1080 --on-ip 192.168.50.1 --tproxy-mark 0x01/0x01
   iptables -t mangle -A PREROUTING -p udp -j SHADOWSOCKS_UDP
   iptables -t mangle -A OUTPUT -p udp -j SHADOWSOCKS_MARK
   ```

   ​