How to run sshd on port 500 in High Sierra?

Solution 1:

To modify the ssh port, you have to edit the ssh launch daemon of the ssh server host:

• disable SIP

• open ssh.plist:

  sudo nano /System/Library/LaunchDaemons/ssh.plist 
  

• modify the <key>Sockets</key> (example port here: 10022) from

      ...
      <key>Sockets</key>
      <dict>
              <key>Listeners</key>
              <dict>
                      <key>SockServiceName</key>
                      <string>ssh</string>
                      <key>Bonjour</key>
                      <array>
                              <string>ssh</string>
                              <string>sftp-ssh</string>
                      </array>
              </dict>
      </dict>
      ...
  

  to

      ...
      <key>Sockets</key>
      <dict>
              <key>Listeners</key>
              <dict>
                      <key>SockServiceName</key>
                      <string>10022</string>
                      <key>Bonjour</key>
                      <array>
                              <string>10022</string>
                              <string>10022</string>
                      </array>
              </dict>
      </dict>
      ...
  

• unload and load the daemon

  sudo launchctl unload /System/Library/LaunchDaemons/ssh.plist 
  sudo launchctl load /System/Library/LaunchDaemons/ssh.plist 
  

• test the ssh daemon
• enable SIP

An alternative, less intrusive approach is to create a second ssh launch daemon in /Library/LaunchDaemons/:

• copy the ssh.plist

  sudo cp /System/Library/LaunchDaemons/ssh.plist /Library/LaunchDaemons/ssh2.plist 
  

• modify the ssh2.plist:

  sudo nano /Library/LaunchDaemons/ssh2.plist 
  

  change the key Label to

  <key>Label</key>
  <string>com.openssh.sshd2</string>
  

  change the key <key>Sockets</key> as described earlier

• disable SSH in the System Preferences > Sharing > Remote Login

• load the launch daemon:

  sudo launchctl load -w /Library/LaunchDaemons/ssh2.plist 
  

• with strict key checking enabled in the ssh config file on a ssh client host you may have to remove the ssh server from the known_hosts file of this remote host.
• access the ssh server with ssh user@IP -p <port>