How to speed up SSH authentication

SSH enables secure log-in to remote computers and is primarily used for system administration. The log-in process could be slow, and it will add up if you need to log in many times a day as part of your job.

There are a few things that could affect SSH login speed, and there are ways that you can take to speed up SSH authentication, which you can implement from both the client and server sides.

1. Disable reverse DNS lookup for SSH server.

   SSH server could be configured to perform a reverse DNS lookup of incoming connection which could delay the log in process.

   Related: How to disable reverse DNS lookup in SSH

2. Disable GSSAPI authentication on SSH server.

   SSH server might have to check if you're using GSSAPI authentication even if you're conecting via other authentication method.

   Related: How to enable or disable GSSAPI authentication in SSH

3. Share and reuse SSH connection via multiplexing.

   multiplexing allows sharing and reuse of SSH connection which could significantly speed up remote SSH server access.

   Related: How to use multiplexing in SSH

4. Manually specify authentication method from SSH client.

   SSH client will try multiple authentication methods unless manually specified.

   Related: How to set preferred authentication method for SSH

5. Use passwordless authentication method.

   Not having to manually key in username and password during log in will speed up SSH authentication.

   Related: How to SSH without password