Currently, I have two VPN clients on most of my devices:

  • One for connecting to a LAN
  • One commercial VPN for privacy reasons

I usually stay connected to the commercial VPN on all my devices, unless I need to access something on that LAN.

This setup has a few drawbacks:

  • Most commercial VPN providers have a limit on the number of simulations connected clients
  • I either obfuscate my IP or am able to access resources on that LAN, including my Pi-Hole fur custom DNS-based blocking

One possible solution for this would be to route all internet traffic through a VPN client on the router in the LAN and figuring out how to still be able to at least have a port open for the VPN docker container allowing access to the LAN. But then the ability to split tunnel around that would be pretty hard to achieve.

I want to be able to connect to a VPN host container on the LAN, which in turn routes all internet traffic through another VPN client container while allowing LAN traffic, but still be able to split tunnel specific applications on my Android/Linux/iOS devices.

Basically this:

   +---------------------+ internet traffic   +--------------------+           
   |                     | remote LAN traffic |                    |           
   | Client              |------------------->|VPN Host Container  |           
   | (Android/iOS/Linux) |                    |in remote LAN       |           
   |                     |                    |                    |           
   +---------------------+                    +--------------------+           
                      |                         |     |                        
                      |       remote LAN traffic|     | internet traffic       
split tunneled traffic|                 |--------     |                        
                      |                 |             v                        
                      v                 |         +---------------------------+
  +---------------------+               v         |                           |
  | regular LAN or      |     +-----------+       | VPN Client Container      |
  | internet connection |     |remote LAN |       | connects to commercial VPN|
  +---------------------+     +-----------+       |                           |
                                                  |                           |
                                                  +---------------------------+

Any recommendations on how to achieve this, especially considering client apps for Android and iOS with the ability to split tunnel per application?

Update:

Got it by following this guide.

Ended up modifying this setup to have better control over potential IP leakage

  • Prison Mike@links.hackliberty.orgEnglish
    2·
    5 months ago

    I use Tailscale to do this. I install the software on everything I can, but for resources on the LAN that don’t have Tailscale running I use its Subnet Router feature to masquerade the traffic and connect to those clients.

    As for the commercial VPN, it’s a bit more involved. I have a few Exit Nodes (VPS) that take incoming Tailscale traffic destined to the Internet and re-route it via the commercial VPN’s WireGuard network interface.

    This was a huge challenge for me (lots of iptables, ip6tables rules) but I have it down to a reproducible script I can provide if you’d like an example.

    My next goal is to containerize the two VPS servers into one with Docker. Tailscale is a bit annoying that you can’t have multiple Nodes running on the same machine (hence my temporary two VPS solution).

    Note: capitalized terms are Tailscale feature names

    • Emotet@slrpnk.netOPEnglish
      2·
      5 months ago

      I’ve been tempted by Tailscale a few times before, but I don’t want to depend on their proprietary clients and control server. The latter could be solved by selfhosting Headscale, but at this point I figure that going for a basic Wireguard setup is probably easier to maintain.

      I’d like to have a look at your rules setup, I’m especially curious if/how you approached the event of the commercial VPN Wireguard tunnel(s) on your exit node(s) going down, which depending on the setup may send requests meant to go through the commercial VPN through your VPS exit node.

      Personally, I ended up with two Wireguard containers in the target LAN, a wireguard-server and a **wireguard-client **container.

      They both share a docker network with a specific subnet {DOCKER_SUBNET} and wireguard-client has a static IP {WG_CLIENT_IP} in that subnet.

      The wireguard-client has a slightly altered standard config to establish a tunnel to an external endpoint, a commercial VPN in this case:

      [Interface]
PrivateKey = XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Address = XXXXXXXXXXXXXXXXXXX

PostUp = iptables -t nat -A POSTROUTING -o wg+ -j MASQUERADE
PreDown = iptables -t nat -D POSTROUTING -o wg+ -j MASQUERADE

PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT

PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT

[Peer]
PublicKey = XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
AllowedIPs = 0.0.0.0/0,::0/0
Endpoint = XXXXXXXXXXXXXXXXXXXX

      where

      PostUp = iptables -t nat -A POSTROUTING -o wg+ -j MASQUERADE
PreDown = iptables -t nat -D POSTROUTING -o wg+ -j MASQUERADE

      are responsible for properly routing traffic coming in from outside the container and

      PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT

PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT

      is your standard kill-switch meant to block traffic going out of any network interface except the tunnel interface in the event of the tunnel going down.

      The wireguard-server container has these PostUPs and -Downs:

      PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

      default rules that come with the template and allow for routing packets through the server tunnel

      PostUp = wg set wg0 fwmark 51820

      the traffic out of the tunnel interface get marked

      PostUp = ip -4 route add 0.0.0.0/0 via {WG_CLIENT_IP} table 51820

      add a rule to routing table 51820 for routing all packets through the wireguard-client container

      PostUp = ip -4 rule add not fwmark 51820 table 51820

      packets not marked should use routing table 51820

      PostUp = ip -4 rule add table main suppress_prefixlength 0

      respect manual rules added to main routing table

      PostUp = ip route add {LAN_SUBNET} via {DOCKER_SUBNET_GATEWAY_IP} dev eth0

      route packages with a destination in {LAN_SUBNET} to the actual {LAN_SUBNET} of the host

      PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE; ip route del {LAN_SUBNET} via {DOCKER_SUBNET_GATEWAY_IP} dev eth0

      delete those rules after the tunnel goes down

      PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark 0xca6c -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -I OUTPUT ! -o %i -m mark ! --mark 0xca6c -m addrtype ! --dst-type LOCAL -j REJECT
PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark 0xca6c -m addrtype ! --dst-type LOCAL -j REJECT && ip6tables -D OUTPUT ! -o %i -m mark ! --mark 0xca6c -m addrtype ! --dst-type LOCAL -j REJECT

      Basically the same kill-switch as in wireguard-client, but with the mark manually substituted since the command it relied on didn’t work in my server container for some reason and AFAIK the mark actually doesn’t change.

      Now do I actually need the kill-switch in wireguard-server? Is the kill-switch in wireguard-client sufficient? I’m not even sure anymore.

      • Prison Mike@links.hackliberty.orgEnglish
        2·
        4 months ago

        Your setup looks more advanced than mine, and I’d really like to do something similar. I’m just going to copy/paste what I have with some addresses replaced by:

        VPN_IPV4_CLIENT_ADDRESS: The WireGuard IPv4 address of the VPN provider’s interface (e.g. 172.0.0.1) VPN_IPV6_CLIENT_ADDRESS: The WireGuard IPv6 address of the VPN provider’s interface VPN_IPV6_CLIENT_ADDRESS_PLUS_ONE: The next IPv6 address that comes after VPN_IPV6_CLIENT_ADDRESS. I can’t remember the logic behinds this but I’d found an article online explaining it. WG_INTERFACE: The WireGuard network interface name (e.g. wg0) for the commercial VPN

        I left 100.64.0.0/10, fd7a:115c:a1e0::/96 in my example because those are the networks Tailscale traffic will come from. I also left tailscale0 because that is the typical interface. Obviously these can be changed to support any network.

        I’m using Alpine Linux so I don’t have the PostUp, PostDown, etc. in my WireGuard configuration. I’m not using wg-quick at all.

        Before I hit paste, one thing I’ll say is I haven’t addressed the “kill switch” yet. But so far (~4 months) when the VPN provider’s tunnel goes down nothing leaks. 🤞

        sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv6.conf.all.forwarding=1

sysctl -p

ip link add dev WG_INTERFACE type wireguard

ip addr add VPN_IPV4_CLIENT_ADDRESS/32 dev WG_INTERFACE
ip -6 addr add VPN_IPV6_CLIENT_ADDRESS/127 dev WG_INTERFACE

wg setconf WG_INTERFACE /etc/wireguard/WG_INTERFACE.conf
ip link set up dev WG_INTERFACE

iptables -t nat -A POSTROUTING -o WG_INTERFACE -j MASQUERADE
iptables -t nat -A POSTROUTING -o WG_INTERFACE -s 100.64.0.0/10 -j MASQUERADE

ip6tables -t nat -A POSTROUTING -o WG_INTERFACE -j MASQUERADE
ip6tables -t nat -A POSTROUTING -o WG_INTERFACE -s fd7a:115c:a1e0::/96 -j MASQUERADE

iptables -A FORWARD -i WG_INTERFACE -o tailscale0 -j ACCEPT
iptables -A FORWARD -i tailscale0 -o WG_INTERFACE -j ACCEPT
iptables -A FORWARD -i WG_INTERFACE -o tailscale0 -m state --state RELATED,ESTABLISHED -j ACCEPT

ip6tables -A FORWARD -i WG_INTERFACE -o tailscale0 -j ACCEPT
ip6tables -A FORWARD -i tailscale0 -o WG_INTERFACE -j ACCEPT
ip6tables -A FORWARD -i WG_INTERFACE -o tailscale0 -m state --state RELATED,ESTABLISHED -j ACCEPT

mkdir -p /etc/iproute2/rt_tables

echo "70 wg" >> /etc/iproute2/rt_tables
echo "80 tailscale" >> /etc/iproute2/rt_tables

ip rule add from 100.64.0.0/10 table tailscale
ip route add default via VPN_IPV4_CLIENT_ADDRESS dev WG_INTERFACE table tailscale

ip -6 rule add from fd7a:115c:a1e0::/96 table tailscale
ip -6 route add default via VPN_IPV6_CLIENT_ADDRESS_PLUS_1 dev WG_INTERFACE table tailscale

ip rule add from VPN_IPV4_CLIENT_ADDRESS/32 table wg
ip route add default via VPN_IPV4_CLIENT_ADDRESS dev WG_INTERFACE table wg

service tailscale start
rc-update add tailscale default

iptables -A INPUT -i tailscale0 -p udp --dport 53 -j ACCEPT
iptables -A INPUT -i tailscale0 -p tcp --dport 53 -j ACCEPT

ip6tables -A INPUT -i tailscale0 -p udp --dport 53 -j ACCEPT
ip6tables -A INPUT -i tailscale0 -p tcp --dport 53 -j ACCEPT

service unbound start
rc-update add unbound default

/sbin/iptables-save > /etc/iptables/rules-save
/sbin/ip6tables-save > /etc/ip6tables/rules-save

tailscale up --accept-dns=false --accept-routes --advertise-exit-node
        • Prison Mike@links.hackliberty.orgEnglish
          2·
          4 months ago

          Forgot to mention that I run a DNS server for blocking too. When using Tailscale I’ve found it’s important to use their resolver as upstream otherwise App Connectors won’t work (the VPN provider tunnels on each VPS routes to different countries so DNS wasn’t in sync). This kind of sucks but I make do with it after a month or two of App Connectors being very iffy.