Great, I spent a few hours today to set up a nice OpenVPN server. Nice in that I wanted the (Windows) clients to be able to access the company network like they were connected locally.

My idea was to use the OpenVPN tap mode and let the DHCP server at work assign IPs to the VPN clients.

This turned out to be a dumb idea. After I got everything going, I noticed the following message in syslog (which probably scrolled by previously in the debug drivel):

NOTE: your local LAN uses the extremely common subnet address 192.168.0.x or 192.168.1.x. Be aware that this might create routing conflicts if you connect to the VPN server from public locations such as internet cafes that use the same subnet.

Hmm, sure, I guess that will exclude every second incoming VPN connection.

Summary: Think about IP space clashes before setting up a VPN.