Skip to main content

slow ssh connections

(5 September 2019)

Problem

When I ssh login to a CentOS 7 system, it always takes around 30 second to log in.

Solution

Turn off the authentication types you don't need in /etc/ssh/sshd_config :

useDNS no
ChallengeResponseAuthentication no
KerberosAuthentication no
GSSAPIAuthentication no
IgnoreRhosts yes
RhostsRSAAuthentication no
HostbasedAuthentication no

With this configuration, the ssh server should still accept both interactive passwords and ssh pubkeys.

Details

Found )here. In my highly specific case, disabling GSSAPIAuthentication made the difference between a 50 second wait to log in and a sub-1-second wait to log in.