Identification String spam from known hosts


Web searches on this issue are polluted by logs of hacking attempts and suchlike; can't find any simple technical explanation of the condition that's actually triggering it, though.

Host's logs are filled with "Did not receive identification string from x.x.x.x" messages when i am connected to the host *from* x.x.x.x at a rate of one every 2-3 minutes. What is the cause of sshd's ire?

x.x.x.x which i am connecting from is a Gentoo system, using ebuild openssh-4.2_p1-r1.
The host is Ubuntu using openssh-server 1:4.1p1-7ubuntu4.

Across the network, i have noticed that a few Debian systems consistently complain in this manner about Gentoo systems that connect to them. I am assuming the ssh client on gentoo is (or isn't...) sending something to the remote host that it doesn't like, but i'm not sure where to start looking, even...

Rob Munsch
Solutions For Progress IT