How to open ssh://username@hostname link

What I could gather, you have to register the protocol in the gconf:

gconftool-2 --set --type=bool /desktop/gnome/url-handlers/ssh/enabled true
gconftool-2 --set --type=string /desktop/gnome/url-handlers/ssh/command 'gnome-terminal -e "%s"'
gconftool-2 --set --type=bool /desktop/gnome/url-handlers/ssh/needs_terminal false

(source)

I can't get it to register ssh in chromium though. Haven't tried with firefox, but these instructions should help.

You can open the ssh link on the command line by using ssh username@hostname (I think you know this already) if you want to access it via nautilus in gnome then you can minimise all windows and do [ctrl]+L which will open a dialog. Type in your url ssh://username@hostname and click open.

This should solve most of your problems. xdg-open can only open the url if the url has been mounted somewhere already. Otherwise it can't access the ssh files.