Extremely slow authentication via SSH on FreeBSD 6.0

Alan Bram arb46 at cornell.edu
Mon Jan 9 09:22:46 PST 2006

Boy, talk about good timing!

I just joined this list yesterday.  The reason I joined was to see if
I could get any help solving what appears to have been (approximately)
this same problem.

I also had the problem of extremely slow SSH authentication.  In fact,
it was so slow that at first I thought is was simply dead, because
most often it would time out and give up.

In my case, I had not made any changes to the system whatsoever.  SSH
had been working fine since I originally installed FreeBSD 5.4 a few
months ago.  But then a few days ago it just suddenly started having
this problem.

In my case, Apache did _NOT_ seem to be suffering from the same

I changed my sshd configuration to set UseDNS to no, and that seems to
have fixed the problem.  So I'm quite happy, and grateful.

However, it does leave me curious ...

Something must have changed in my network (a small home network on a
DSL router), I guess, but I don't know what.

> I posted a similiar problem on Sunday but didn't get any responses.  I 
> turned off DNS in the sshd_config file and the sshd time out problem went 
> away for me as well.   Actually I had to turn off dns lookup up for apache 
> and proftpd as well because those services were running extremely slow or 
> not responding. 
> If you've not made any modifications to your system, why would this happen?

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