on certain ssh-servers the ssh-client fails with "xmalloc: zero size" and exits immediately before asking for a password or so. What I found was: http://www.gossamer-threads.com/lists/openssh/bugs/44110 "ssh fails with xmalloc: zero size when connecting to a server with present but empty banner." where there is also a patch mentioned for OpenSSH 5.1b1. And somebody mentioned workarounds, which I didn't yet try: http://utcc.utoronto.ca/~cks/space/blog/solaris/FixingSolarisSsh
This is already fixed in the testing update and 5.1p1 is not in released updates yet.
Pending update from testing fixes it. Tried, looks good. Other bug-ID I found for this: #457326