SSH slow to login? Disable reverse DNS lookup

By default in Ubuntu (and probably other distributions), when you log into the SSH server, it will do a reverse DNS lookup of the client for security reasons.

That’s fine, but it’s kind of annoying when you don’t have a working reverse DNS for your IP address. Like for all my internal addresses.

To turn it off (thanks to

Edit /etc/ssh/sshd_config and add the following line:

UseDNS no


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