vpn backend does not route return packets on Darwin

[scareything]

I set up a vpn share, the backend was created on Darwin and it was accessed from a Windows host. An ssh connection from the Windows host didn't work initially. A packet capture on the Mac showed that the segments from the ssh client on Windows were arriving, but the return segments were going out on the Mac's default route and not making it to the client host.

The connections started working after I manually added a route to send subnet packets through the tun interface:

sudo route add 10.122.0.0/16 -interface utun5