How to configure SSH Server to listen on multiple ports

Configuring SSH to listen on multiple ports provides flexibility for environments that span different networks, firewalls, or access policies. Additional ports can separate administrative access, support alternative forwarding rules, or allow migration away from a heavily filtered default port without interrupting existing connections.

The sshd daemon reads listener definitions from the /etc/ssh/sshd_config file and creates a TCP listener for every Port directive it finds. When multiple Port lines are present, sshd binds to each of them on IPv4 and IPv6, subject to any restrictions imposed by the local firewall or access control lists.

Each additional port must be opened in the host firewall and permitted by any SELinux policy applied to sshd. Failing to update these layers can cause connections on the new port to hang or be rejected even though the daemon is running, and incorrect changes to listener settings can make remote logins impossible if no alternative access path is available.

1. Open a terminal session on the server with access to an account that can use sudo.

   $ whoami
   admin

   Any account able to edit /etc/ssh/sshd_config and restart sshd is suitable.

2. Inspect existing SSH listening ports to confirm that the additional port is free.

   $ ss -tlnp | grep -E "22|2022"
   LISTEN     0      128          *:22                       *:*
   LISTEN     0      128         :::22                      :::*

   Output showing only port 22 indicates that port 2022 is not yet in use.

3. Open the sshd configuration file in a text editor with elevated privileges.

   $ sudo vi /etc/ssh/sshd_config

   vi is used here, but any preferred editor such as nano or vim works.

4. Locate the existing Port directive near the top of the file or add one if it is missing.

   Many distributions ship a commented example such as #Port 22; remove the leading # to activate it.

5. Add a separate Port line for each TCP port that sshd should listen on.

   Port 22
   Port 2022

   Each listener requires its own Port directive, and all active directives must remain uncommented.

   A line beginning with # is treated as a comment and ignored, which can unintentionally disable a listener or leave only a nonstandard port active.

6. Save the file and exit the editor after confirming that only the intended Port lines are present.

   Retain at least one known-good port until connectivity on any new ports is verified.

7. Validate the updated configuration before restarting the daemon.

   $ sudo sshd -t

   No output from sshd -t indicates that the configuration syntax is valid.

   If an error message appears, revert or correct the changes before restarting sshd to avoid losing remote access.

   Related: How to check and validate SSH server's configuration

8. Permit the new port through the host firewall if filtering is enabled.

   $ sudo ufw allow 2022/tcp
   Rule added
   Rule added (v6)
   $ sudo firewall-cmd --add-port=2022/tcp --permanent
   success
   $ sudo firewall-cmd --reload
   success

   Use the ufw command on systems that rely on UFW (commonly Ubuntu or Debian) and the firewalld commands on systems such as CentOS or Red Hat.

   Exposing additional ports increases the attack surface, so combine these rules with network-level filtering and strong authentication.

9. Register the new port with SELinux so that sshd is allowed to bind to it when enforcement is enabled.

   $ sudo semanage port -a -t ssh_port_t -p tcp 2022

   The ssh_port_t type labels the port for SSH traffic, aligning the listener with the existing security policy.

   If semanage is not available, it can be installed on CentOS or Red Hat using a package such as policycoreutils-python or policycoreutils-python-utils, for example:

   $ sudo yum install --assumeyes policycoreutils-python

10. Restart the sshd service to apply the new listener configuration.

    $ sudo systemctl restart sshd

    Some distributions name the unit ssh instead of sshd; adjust the command accordingly if the restart fails with a unit-not-found error.

    Restarting sshd replaces the running daemon, so invalid settings can prevent new logins even if current sessions remain open only temporarily.

    Related: [DRAFT] How to manage the SSH server service with systemctl in Linux

11. Confirm that the sshd service is running cleanly after the restart.

    $ sudo systemctl status sshd
    ● sshd.service - OpenSSH server daemon
         Loaded: loaded (/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
         Active: active (running) since Thu 2025-01-09 09:34:00 UTC; 5s ago
    ##### snipped #####

    The Active: active (running) line confirms that the daemon started successfully with the new configuration.

12. Verify that sshd is listening on all configured ports.

    $ ss -tlnp | grep -E "22|2022"
    LISTEN     0      128          *:22                       *:*
    LISTEN     0      128          *:2022                     *:*
    LISTEN     0      128         :::22                      :::*
    LISTEN     0      128         :::2022                    :::*

    Entries for both 22 and 2022 on IPv4 and IPv6 confirm that the SSH server is listening on multiple ports.

    If the new port does not appear, review firewall and SELinux settings and inspect logs using journalctl for startup or binding errors.