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Change the SSH Port in CentOS and Red Hat

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Change the SSH Port in CentOS and Red Hat

This article explains how to change the default Secure Shell (SSH) port on a CentOS® or Red Hat® Enterprise Linux® server.

Open and edit the SSH daemon configuration file

  1. Run the following command to open the sshd_config file:

    [root@server-01 ~]# vi /etc/ssh/sshd_config

  2. Use the arrow keys to scroll through the file until you locate the following text:

     #Port 22
 #AddressFamily any
 #ListenAddress 0.0.0.0
 #ListenAddress ::

  3. Place the cursor on the line below #Port 22 and press the i key to enter Insert Mode.

  4. Press the Enter key to create a new line and type Port <Specified Port Number>. Port 2021 is the new SSH port in the following example:

     #Port 22
 Port 2021
 #AddressFamily any
 #ListenAddress 0.0.0.0
 #ListenAddress ::

  5. Press the Esc key to exit Insert Mode. Next, quit vi by typing :wq and pressing the Enter key.

Bind SSH daemon to the new port

  1. Install the policycoreutils package to bind the SSH daemon to the new SSH port by using the following command:

    [root@server-01 ~]# yum install policycoreutils

  2. Type y and press the Enter key to continue with the installation. When this task completes, add the following rules to ensure that the SSH daemon binds with the specified port:

    [root@server-01 ~]# semanage port -a -t ssh_port_t -p tcp 2021
[root@server-01 ~]# semanage port -m -t ssh_port_t -p tcp 2021

  3. Next restart the SSH daemon:

    [root@server-01 ~]# systemctl restart sshd

Verify the bind to the new port

Ensure that the port changes took effect by using either the netstat or ss command as shown in the following example:

    [root@server-01 ~]# ss -tlpn| grep ssh
    LISTEN   0         128                 0.0.0.0:2021             0.0.0.0:*        users:(("sshd",pid=28065,fd=4))
    LISTEN   0         128                    [::]:2021                [::]:*        users:(("sshd",pid=28065,fd=6))
    [root@server-01 ~]# netstat -tlpn| grep ssh
    tcp        0      0 0.0.0.0:2021            0.0.0.0:*               LISTEN      28065 sshd
    tcp6       0      0 :::2021                 :::*                    LISTEN      28065 sshd

As you can see, both commands show that Port 2021 is now in place.

Update your firewall

Update your firewall to ensure that incoming connections are allowed to the newly specified port. Enter the following two lines:

    [root@server-01 ~]# sudo firewall-cmd --add-port=2021/tcp --permanent
    success
    [root@server-01 ~]# sudo firewall-cmd --remove-service=ssh --permanent
    success

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