[lug] SSH slows to a crawl

[Zan Lynx]

Gordon Golding wrote:
> 
> SSH on 2 out of 3 linux FC11 servers has slowed to a crawl.
>  
> We have 3 Linux servers all plugged into the same hub.
>  
> Yesterday, they were all fast with ssh and other connections.
>  
> Today, 2 out of the 3 suddenly have very very slow ssh connection 
> speeds, taking seconds to respond.  But other connections are not slow.
>  
> Any combination ssh connection involving a Slow server is slow.
> BUT -
> If you ping the slow ones from in the room (same hub) or out of the 
> room, through a switch, ping is fast:  0.180 ms or 0.284 ms, for example.
> Other things like HTTP seem just fine, too.
> 
> Looking at /var/log/secure, I see no attempted connections.
> 
> SELinux has been disabled.  No effect.
> CPU is only at 0.3 usage.
>  

Are you talking about transfer speeds or the time it takes to open a new 
SSH connection?

If it is slow times on new connections, it is probably a DNS problem. 
SSH normally does extra DNS checks with reverse lookups.

If your DNS administrator reconfigured some zones, or if your DNS 
servers became unavailable, or someone removed entries from /etc/hosts, 
or ...


-- 
Zan Lynx
zlynx at acm.org

"Knowledge is Power.  Power Corrupts.  Study Hard.  Be Evil."