How to perform routing?

Question

linux

Colleagues, good afternoon.
Please help me to form the iptables command
there are 3 interfaces eth0 (192.168.100.0), tun0 (10.10.10.0) and tun1 (10.10.11.0)
now the rules are:
ip rule add from 10.10.10.0/24 table vpn.out
ip route add default dev tun1 table vpn.out iptables
-t nat -A POSTROUTING -s 10.10.10.0/24 -o tun1 -j MASQUERADE

Answer 1

1) s/MASQUERADE/SNAT/
No need to force the processor. The masquerade was invented for ppp when their address is not known in advance.
2) in the same way (in the sense, the first would also be brought to a similar form)

iptables -t nat -A POSTROUTING -i tun0 -s 10.10.10.0/24 -o eth0 -d 192.168.100.0/24 -j SNAT --to-source 192.168.100.x