My Ubuntu Subversion server is not directly accessible to the Internet, 192.168.1.2
My public Ubuntu machine is exposed through the DMZ at 192.168.1.1
I've setup port forwarding from 192.168.1.1:3906 to 192.168.1.2:3906, but I have no idea how this would work with svn+ssh since one extra hop is required to reach my Subversion server
edit: For anybody going through the same problem, my confusion came because I was trying to port forward to my SVN server (running a daemon at port '3906') but accessing your SVN server through SSH is totally different from accessing your SVN server running a daemon (at 3906). You need to treat this as a typical ssh connection. Both of the methods below worked once I edited my settings