Slow SSH login on VMWare ESX and ESXi

If you’re experiencing slow SSH logins on your VMWare ESX and ESXi hosts, I might just have the fix for you.

I had the slight feeling that logging on one of my servers was horribly slow.. as if some delay was applied upon login but it actually is a DNS problem : the SSH Server is trying to get the reverse DNS of the client connecting to it…

This can be disabled and fixed very easily 🙂

Here are the steps to follow to get back to a fast connection:
– Login on the server via SSH
– Edit the file /etc/ssh/sshd.config for example with vi /etc/ssh/sshd.config
– Check if the parameter useDNS exists. If it does change its value to no otherwise add useDNS no to the file
– Save your changes
– Next login should be fast again