How to set a route through a specific interface and tunnel?

Question

Computer networks

There is a physical eth0 (192.168.1.4), a virtual interface veth0 (192.168.3.1) and a network namespace "NS" which uses veth0 as the gateway. In NS mode, a vpn tunnel (192.168.9.68) has been raised, through which there is a route to addresses 10.5.0.x. That is, from under NS you can reach 10.5.0.43.

How to determine the route from the space 192.168.1.4 to the address 10.5.0.43?
trite route add 10.5.0.43 via 192.168.3.1 dev veth0 does not work

Answer 1

I've never done this, but I'll throw in general considerations. Would it help?
is the second end of veth0 from the NS side configured?
is there a return route? from vpn to 192.168.1.4?
in NS is it written sysctl -w net.ipv4.ip_forward=1?