Stephen,

Thanks for your quick reply. It was indeed the reverse DNS lookups; 
maybe something changed on a DNS server somewhere. I just replaced 
resolv.conf with one from a working machine and we're back in business :).

Thanks for the help!

Cheers,
Andy

Stephen John Smoogen wrote:
> On Wed, Jan 13, 2010 at 3:34 PM, Andy Mastbaum <[log in to unmask]> wrote:
>> Hello, all.
>>
>> I'm having a weird problem with my SL 5.3 login server. All of a sudden (and
>> without me changing anything) logins over SSH are very, very slow -- up to a
>> few minutes.
>>
>> Once users are logged in, everything is fast. This doesn't happen when I log
>> in at the console, only over the network.
>>
>> I tried restarting every network service, rebuilding the NIS directory, and
>> finally rebooting the server, and nothing has helped.
> 
> Most cases this is a reverse DNS problem. This can make things even
> slower with good old NIS.
> 
> 1) Check that the system is able to get DNS info correctly ( eg host
> 10.5.10.10 if the client comes from there and see where its stuck).
> 2) ssh -vvv is your friend on seeing if its client side.
> 3) sshd -p 2222 -ddd is your friend to see whats going on the server side.
> 4) if nscd is on. try turning it off and cleaning its cache.. that
> will remove another vector.
> 
> Usually one can see pretty quick that its something like a lookup
> failing or bad nscd cache etc.
> 
>> This is SL 5.3, Linux 2.6.18-128.1.10.el5 #1 SMP x86_64, user info is NIS
>> (on the same server), and home directories are NFS-mounted, but NIS and NFS
>> should be okay since local logins are fast. I'd think a problem with the
>> NIC, but it's a nice Intel PRO/1000 and it's only the authentication that's
>> slow.
>>
>> Any thoughts/suggestions are much appreciated... my users are getting pretty
>> unhappy :(
>>
>> Thanks!
>>
>> Andy Mastbaum
>> [log in to unmask]
>>
> 
> 
>