XenServer modifies the SSH (22) connection port to improve the security of the server

Modify Port:
vi /etc/ssh/sshd_config

Find "#Port 22", remove the previous "#", and modify "22" to the port you need, as follows:
# vi /etc/ssh/sshd_config
Port 6123
Save ,quit!

Modify firewall configuration (XenServer virtualization server has firewall settings by default)
vi /etc/sysconfig/iptables

find
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT

Modify "--dport 22" to the previously modified port "--dport 6123"

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 6123 -j ACCEPT

save and exit , restart the firewall
/etc/init.d/iptables restart

and then restart SSHD
/etc/init.d/sshd restart After

completing the above two steps, you can test the connection, and quickly try to connect.

      Note: If you connect to the XenServer server remotely through the ssh client, it is recommended to link 2 Putty (that is, 2 remote sessions) before the operation. Even if the modification is wrong, the recovery operation can be performed through another session.
      In addition, the port (XenServer-specific) can also be modified through XenCenter.
      Note: Changes to the server-side ssh port have been found in testing to have no effect on XenCenter connections. XenCenter doesn't sense port changes.