L2TP over IPsec on Cisco IOS

Written in the mid-afternoon in English • Tags: , , , , ,

I wanted to use the OS X VPN client to connect to my home network while on the road. I guess using an OS X server would be the easiest way to get a Mac-compatible VPN server up and running. Using a Cisco running IOS required quite a few lines of configuration.

The OS X VPN client provides terrible feedback. It will happily tell you that there was “no response from the VPN server” when in reality the server responds with a rejection of all the ISAKMP or IPsec transforms proposed by the client. Fortunately both the Cisco debugging messages and verbose output from tcpdump were quite helpful.

In about 3 hours I got it all working, including routing with other VRFs and DMVPN sites. (more…)