SSH
server is by default configured to perform reverse DNS
lookup of your IP
address every time you try to log in to the server. It could slightly improve logging and security, but would significantly increase login time.
Basically the login prompt could take a while to appear as the server will perform reverse DNS
lookup on the incoming IP
address prior to presenting the login prompt.
You can fix this issue by disabling the UseDNS
directive on the SSH
server from the terminal.
UseDNS
Specifies whether sshd(8) should look up the remote host name
and check that the resolved host name for the remote IP address
maps back to the very same IP address. The default is “yes”.
SSHd
configuration file using a text editor. $ sudo vi /etc/ssh/sshd_config [sudo] password for user:
UseDNS
directive and set the value to no
. UseDNS no
Add the line if it doesn't already exist and remove the #
at the beginning of the line if existing line starts with #
.
SSH
server service. $ sudo systemctl restart sshd
Guide compatibility:
Operating System |
---|
Ubuntu Linux |
Debian Linux |
Red Hat Enterprise Linux |
Fedora Linux |
CentOS Linux |
openSUSE Linux |
SUSE Linux Enterprise Server |
FreeBSD |
OpenBSD |
NetBSD |
macOS |
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