VPN

Hi there,

I've been using M0n0wall for years now, dozens of installs, all with PPTP vpn, all working great. I setup the latest router, working fine, pptp working fine, then today, random packet corruption over vpn. Some symptoms:

RDP connections fail with Encryption payload fails
SSH connections fail with "packet returned garbeled"
Internal websites only load partial data (part correct, part garbage)

Some things seem to be working fine. ping is 100%, low latency.  SMB shares seem to be working fine.

I've tried changing the MTU setting, and even tried building a whole new router, on new hardware, with a new WAN IP, it gives the same errors!

Has anyone seen this before or have any clue what it could be? 

I have seen it a few times when ISPs implement badly thought out DPI.  You need to set up a 3rd point in your VPN triangle an see who is the common denominator.

Actually, I think I found the root cause, the subnet on the LAN side is 10.0.0.0 255.0.0.0
and the remote side also 10.0.0.0/255.255.255.0, when I connect from a 192.x LAN to the VPN it works fine.

I've had overlapping subnets before and the VPN just didn't work, so I didn't think that was related. That combined with it working well for a couple weeks made me look in another direction. Really not looking forward to changing our IP addressing scheme.


Thanks!
Aaron

You can't have both LAN segments behind VPNs belonging to the same network. It's an ambiguous configuration. One or the other will have to change.