[vpn-help] Can't ping/ssh over vpn [Shrew Soft ver 2.1.5 on Ubuntu 10.04]

[r hayman]

Matthew's solution
http://lists.shrew.net/mailman/htdig/vpn-help/2008-November/001827.html
is correct, however, for some reason, you may not see success
immediately.

I experienced the exact same thing (with ModeConfig and virtual adapter
settings only, all other VPN configurations worked as expected) under
Ubuntu 10.04 64-bit desktop.  If you read RFC1812, you will understand
that these settings only affect virtual adapter configs.

I set rp_filter=0 in sysctl.conf and sysctl.d/10-network-security-conf,
rebooted, and verified the settings, yet it didn't work for me either
(at first).

You may have to wait for the SA timeouts and try again, or reboot the
remote VPN endpoint (firewall/router).

Eventually the rp_filter changes did fix the problem, but I have no idea
why it did not work at first.