Tunneldigger is one of the projects of wlan slovenija open wireless network. It is a simple VPN tunneling solution based on L2TPv3 tunnels supported in recent Linux kernels.
Documentation is found at:
Opkg (OpenWrt) packages for both Tunneldigger client and broker are available at:
Source Code, Issue Tracker and Mailing List
For development wlan slovenija open wireless network development Trac is used, so you can see existing open tickets or open a new one there. Source code is available on GitHub. If you have any questions or if you want to discuss the project, use development mailing list.