[QUESTION] question about iptables and ip route on android

[Beat-YT]

Hello, I am trying to get Wifi-Calling to go through my VPN.

I tried to use iptables to do so, without success.

Wifi calling uses uid 1001 and udp port 500 and 4500.

I tried this:

Create a table that is used when marked by 2

ip rule add fwmark 2 table 3

Set what the table do. Make everything that falls under the rule go through the VPN (tun0)

ip route add 0.0.0.0/0 via 10.8.0.26 dev tun0 table 3

Then the iptable rule to mark everything from udp port 500 to tun0:

iptables -t nat -A PREROUTING -i wlan0 -p udp --dport 500 -j DNAT --to-destination 10.8.0.26:500
iptables -A FORWARD -i wlan0 -o tun0 -p udp --dport 500 -j ACCEPT
iptables -t nat -A POSTROUTING -o tun0 -p udp --dport 500 -j SNAT --to-source 10.8.0.26

this is obviously not working.

[Beat-YT]

[Mygod]

It looks like you should bypass the Phone app in your VPN app.

[Beat-YT]

But I’m trying to get to go thorough the VPN

[Mygod]

Your VPN should support UDP first.

[Beat-YT]

Your VPN should support UDP first.

You don’t get it, normally wifi calling does not pass through the VPN and I want to make it pass through. I need an ip table rule or something like that