You may expirence a ssh login dealy, between entering your username and the password prompt.
The cause of the delay, is when SSHD service performs reverse DNS lookup to the client’s ip address.
You can disable this feature in /etc/ssh/sshd_config
Start by makeing a backup of the file.
[Expert@gw2:0]# cp -v /etc/ssh/sshd_config /etc/ssh/sshd_config_ORIGINAL
Now edit the file with vim.
[Expert@HostName]# vi /etc/ssh/sshd_config
Search for this line “#UseDNS yes”
Push Insert button and add “UseDNS no” on the line below
The file should now look like this.
#ShowPatchLevel no
#UseDNS yes
UseDNS no
#PidFile /var/run/sshd.pid
MaxStartups 10:30:100
To quit and save your settings do the following.
1. Esc
2. Shift + Q
3. wq! + Enter (w for write q for quit)
Now you should be out of vim, and can restart the service with the command below.
[Expert@gw2:0]# service sshd restart
Stopping sshd: [ OK ]
Starting sshd: [ OK ]
[Expert@gw2:0]#
Now you whould no longer have SSH login delay. 🙂
For more info see Secure Knowledge article sk106497
Delay between user name and password prompts when log in to the gateway via SSH