The following text has been added to
http://cvs.xemacs.org/#committers
You can debug your ssh connection by doing something like ssh -v
cvs.xemacs.org, and on connecting (there will be no prompt) entering
the command noop, and if ssh is working, getting the response ok.
...
You can test this by running a harmless CVS command, like cvs-rw diff
version.sh.