How to specify a network interface name for an individual application?

Question

linux

Situation: a computer with a 3G modem plugged into it (ppp0) and connected to a certain router (eth0). For the first, pppd is used, for the second, NetworkManager.
How to make, for example, Chromium go to the Internet through ppp0, and not through eth0?

Answer 1

Through iptables, you can mark the packets of a specific application,
then create a separate routing table for the marked packets and route it to the interface you need.
in general, not the easiest way, and earlier, certain iptables extension packages were needed for this, the
second way to register a proxy in chrome and throw the route to the proxy on the desired interface one line with
ip route add bla bla lba

Answer 2

Look towards network namespaces.