Accounts on sourceware.org/gcc.gnu.org/cygwin are not usually provided with shell access. Instead the various version control systems (CVS, SVN, GIT, mercurial, etc.) are handled specially. If you are a project maintainer and believe you have a need of shell access, contact the overseers to make your case.
Note that your sourceware.org/gcc.gnu.org/cygwin account name may differ from your your userid on your client workstation! If so, remember to pass the sourceware username in your ssh operations. You can do this manually:
ssh USERID@sourceware.org ....or code it into your $HOME/.ssh/config.
If you cannot log on, check the user-name first - you can fix that yourself. It is also possible that your ssh key is lost, or too old/insecure. If so, email to firstname.lastname@example.org to plead your case for a manual key replacement.
Some special commands are also available to provide account management functions. These are:
$ ssh sourceware.org appendkey < newkey.pub
Replace all existing SSH keys in your account's SSH authorized_keys file with the supplied key. Example:
$ ssh sourceware.org replacekey < newkey.pub
Set the forwarding address for mail sent to your account on sourceware (email@example.com or firstname.lastname@example.org). Example:
$ ssh sourceware.org email email@example.com
Check whether sourceware/gcc.gnu.org is alive, and its load. Example:
$ ssh sourceware.org alive Linux sourceware.org 2.6.XX-YY.ELsmp #1 SMP Mon Jan 1 12:34:56 EDT 2008 i686 i686 i386 GNU/Linux 12:28:32 up 374 days, 13:07, 4 users, load average: 3.41, 3.58, 3.25