Delays in ssh logins

I have 2 computers on either side of a linux router. Whenever I try to
use ssh to login there appears to be a long delay 15 -30 secs between
the time I enter the user and then get the request for password. This
only appears to happen on the computers when I go through the router.
ComputerA --------- Linux Router ---------ComputerB
once the connection is established everything seems to work fine.
There doesn't appear to be any delays in command response or lap in
typing on the command line. Is there something on linux router that I
should look for that might explain this? If I log into ComputerA
from another computer on it's side of the router there doesn' t appear
to be any delay , the same goes for ComputerB. Is there something in
the routing that I should be looking for?

(E-Mail Removed) wrote:
> I have 2 computers on either side of a linux router. Whenever I try to
> use ssh to login there appears to be a long delay 15 -30 secs between
> the time I enter the user and then get the request for password. This
> only appears to happen on the computers when I go through the router.
> ComputerA --------- Linux Router ---------ComputerB
> once the connection is established everything seems to work fine.
> There doesn't appear to be any delays in command response or lap in
> typing on the command line. Is there something on linux router that I
> should look for that might explain this? If I log into ComputerA
> from another computer on it's side of the router there doesn' t appear
> to be any delay , the same goes for ComputerB. Is there something in
> the routing that I should be looking for?

Could it be a reverse DNS lookup thing? If your router is doing NAT
this would be a very likely cause. Check if your DNS and/or hosts
files are correct and working. If, for whatever reason, you don't
want the computers to resolve hosts on the other side of the router,
try turning off UseDNS in sshd_config.

HTH
-Chris