intermittent ssh connect error

Darren Tucker dtucker at
Fri Oct 19 07:30:33 EST 2007

Paul Archer wrote:
> We've got set of servers that use AFD ( to scp files 
> to a set of receiving servers. There are about 25 sending machines, and 12 
> receiving machines. All the servers are RHEL 4 and 5, with the senders 
> running openssh 4.3p2, and the receivers running 3.9p1.
> Most files are sent without a problem, but on a pretty regular basis, we 
> get "ssh_exchange_identification: Connection closed by remote host" in our 
> log files on the senders.
> The odd/interesting thing is that while that error often shows up on a 
> connection to one machine, we also get bursts, where the error happens on 
> connections to several different machines at once. That leads us to think 
> it's an issue on the sending side, rather than the receiving side.

I suspect you're hitting the MaxStartups unauthenticated connection 
limit.  It default is 10, try bumping it on the servers to, say, 30 or 40.

Darren Tucker (dtucker at
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

More information about the openssh-unix-dev mailing list