[Cialug] Routing Weirdness

[Zachary Kotlarek]

On Jan 28, 2014, at 1:56 PM, L. V. Lammert <lvl at omnitec.net> wrote:

> Most of the time everything works fine, but, randomly, normal traffic from
> theremote site gets routed through the Main site! For example, these
> traceroutes were done in sequence:


Are you sure the VPN router is configured to prefer the non-VPN link for non-VPN traffic? If the two routes were configured with equal priority the expected behavior would be exactly as you describe — some traffic routes directly, some goes across the VPN.

For that matter, you probably don’t want your router to have a default route via the VPN at all — unless you have some reason to forward Internet-bound traffic over the VPN it should only have routes for the specific subnet(s) inside your remote network.


> The machines with problems are all XP, and my working theory is that after
> using a program on a network share (192.168.1.145), XP wants to use the
> 192.168.1 network for some strange reason, but I have not been able to
> prove it.


Generally speaking hosts have no way to direct influence upstream IP routing decisions. Unless you’ve got some weird layer-2 stuff happening, or some out-of-band client-side interaction with the routers, I wouldn’t expect this to have anything to do with desktop hosts.

	Zach

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