Re: OpenSSH's sshd drops connections

On 26 jul, Nejc Škoberne wrote:
> I manage around 50 FreeBSD servers and I have created a script which does
> some work every 5 minutes. Actually this script transfers some files to/from
> the central server, which is running a OpenSSH's sshd
> (OpenSSH_4.5p1 FreeBSD-20061110, OpenSSL 0.9.7e-p1 25 Oct 2004). So I use
> sftp (I have also tried scp) on client sides to perform the task.
>
> The problem is, that (apparently because all the servers start transferring
> files at approximately the same time), some clients are able to do the 
> transfers
> and others are not.
[deleted]
> Do you have any ideas why the central server's sshd drops the connections?

The ssh server will only allow a certain sessions at a time to be in the
authentication phase. This is controlled by the MaxStartups option,
which defaults to 10. The symptoms you see matches what happens when
this triggers.

Note that setting up the encrypted tunnel is potentially quite stressful
for the machine, and if the time gets more synchronized (think ntp) this
will probably become a bigger problem. The best solution is, IMHO, to
add a random delay to the clients rather than just increasing
MaxStartups.

        /MaF
-- 
Martin Forssen <maf@appgate.com>              Development Manager
Phone: +46 31 7744361                         AppGate Network Security AB