• linux
• multihome
• openvpn

Linux multihome openvpn

Setup of OpenVpn on multihome box.

• Problem is Openvpn answers udp packets back using default Gw, and selects different ip than incoming ip.

• OpenVpn: Bind to all interfaces.

  • Linux selects int/ip based on routing. Local gen packets select int before mangle can replace fwmark.

• OpenVpn: Bind to lo:127.0.0.2, use nat to nat incoming on udp:1194 to 127.0.0.2.

  • Kernel bug ? Still selecting wrong source

• OpenVpn: Multiple instances each bound to specific ext ip.

  • WORKS! but need separate subnet for each instance, thus client ip changes when re-connects.