How to Speed up SSH/SFTP Logins

There are two things that generally will slow your login via SSH or SFTP. The first is that by default SSHD will attempt to do a reverse DNS lookup on your IP address to log a DNS name instead of just the IP. If you do not have a reverse DNS, this can cause delays. The second is GSSAPI Authentication which is used with Kerberos. Having the server wait for a Kerberos token timeout just increases delay. If you don’t use Kerberos, disable it.

To disable these settings, modify /etc/ssh/sshd_config:

#GSSAPIAuthentication yes
GSSAPIAuthentication no

#UseDNS yes
UseDNS no

You then need to reload the SSHD daemon. Any established connections will not be affected.

service sshd reload

Note: Before you log off of your SSH session, open a second session to verify SSH is still functional. If it is not, you will still be able to troubleshoot the problem with your existing SSH session.

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