This question is only related to R-devel in that I need to work out how to reach R-forge.R-project.org to update and commit files of R packages for which I am a developer. My desktop computer at work runs Ubuntu 8.04. Because this is not a supported operating system this computer is behind a firewall. I can use a proxy server for http, https and rsync connections. However, the proxy server does not allow outgoing (or incoming) ssh connections. I can use ssh to log in to a local computer that is not behind the firewall and then use svn+ssh to contact R-forge. I have managed to get myself into a bind with that scheme, however. I added and deleted files on the checked out copy on the shared file system using my desktop and then could not check in the changes from the "visible" machine because of svn version skew. The "visible" machine has an out-of-date version of svn. Does anyone know how to tunnel ssh over ssh and, further, how I would specify that in the svn checkin? If my desktop computer is A, the "visible" computer is B and the R-forge server is C then I want to use ssh to set up a tunnel between A and B so that A can reach C for an svn+ssh checkin. Off-list replies would be welcome.