Is your ssh login slow? It could be DNS issue

There could be  various reasons that could result in slow ssh login. Usually it's DNS configuration issue on your server.

In my SUSE environment,

#ping www.google.com

would wait 15 seconds before it displayed something like this

PING www.l.google.com (74.125.227.19) 56(84) bytes of data

I had similar 15 seconds delay for ssh login. Thus, I used following option in  sshd_config file (located under /etc/ssh/sshd_config)

UseDNS  no

Restart SSH Daemon

#service sshd restart

Now there is no delay in SSH login.

However delay in pining google.com was still bothering me. Finally I figured out that you shouldn't be changing DNS configuration from /etc/resolv.conf if you are using netconfig or YaST tool. Thus to clean this mess, I ran following commmand

#netconfig update -f

This command updated  resolv.conf as per netconfig/YaST configuration for DNS and my pinging issue was resolved.
I know you might be thinking of enabling UseDNS for ssh. Yes, you can do it as DNS issue is resolved.

Good Luck