[CentOS] Delay in SSH login..

Mon Apr 3 23:40:51 UTC 2006
Jim Perrin <jperrin at gmail.com>

On 4/3/06, siva m <tech.sivam at gmail.com> wrote:
> Hi,
> I have CentOS 4.3 running on my AMD Athlon XP(32 bit) PC and Windows 2000
> running on my other Intel P3 PC(These 2 PCs are connected using a network
> switch). Basically I use the one running Linux as back end server and
> everything was fine so far. But recently I am experiencing some delay in
> loggin in to CentOS through SSH.
> The Putty client which I use generally opens up asking for username
> prompt(no delay in that) but after entering the password it takes atleast
> 10-15 seconds gap before I logged in.
> It was fine before and I am sure I didn't made any changes to linux
> configuration. Can anyone please help me with this issue.
> By the way I always use the IP address like($ ssh user at 192.168.0.xxx without
> any hostname)

This is where ssh is doing a reverse DNS lookup, which is failing and
timing out. Set up DNS , or turn off the reverse lookup check in the
sshd config. Of the two, setting up DNS is the best option, but
involves a bit more work.

Any sufficiently advanced technology is indistinguishable from magic.
-Arthur C. Clarke