Re: ssh hangs for 5 seconds for a particular machine
On 2015-04-08 13:46:06 -0400, Michael Graham wrote:
> On 8 April 2015 at 13:41, Vincent Lefevre <email@example.com> wrote:
> > # /usr/sbin/sshd -D -ddd -p 80 -f /etc/ssh/sshd_config 2>>(ts -s "%.s")
> > [...]
> > 3.315346 debug3: Trying to reverse map address 188.8.131.52.
> So sshd is doing the reverse lookup and fails
Yes, but with nslookup, the failure is *immediate*. So, this doesn't
explain the 5-second delay.
> You probably want to add (or modify) the UseDNS setting to your sshd
> config file.
> UseDNS Specifies whether sshd(8) should look up the remote host name
> and check that the resolved host name for the remote IP address maps
> back to the very same IP address. The default is “yes”.
Thanks, this solves the problem.
(I've also reported the DNS issue to the sysadmin.)
Vincent Lefèvre <firstname.lastname@example.org> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)