Ubuntu: Change the SSH Port in the operating system
To gain privileges in Linux we use two commands:
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sudo su |
Update the firewall
Update the firewall to ensure that the system allows incoming connections to the newly specified port. Enter
the following command with your new port:
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root@server-02:~# ufw allow 30022/tcp Rules updated Rules updated (v6) |
Edit the SSH daemon configuration file
Perform the following steps to edit the configuration file:
1)Run the following command to open the sshd_config file:
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root@server-02:~# vi /etc/ssh/sshd_config |
2)Use the arrow keys to scroll through the file until you locate the following text:
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#Port 22 #AddressFamily any #ListenAddress 0.0.0.0 #ListenAddress :: |
3)Move the cursor to the line below the #Port 22 line and press the i key to enter Insert Mode.
4)Press Enter to insert a new line and enter Port <Specified Port Number>. Port 2021 is the new SSH port in the following example:
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#Port 22 Port 30022 #AddressFamily any #ListenAddress 0.0.0.0 #ListenAddress :: |
5)Press the Esc key to exit Insert Mode and enter :wq to save your changes and close the file.
Restart SSH daemon
To restart the SSH daemon and complete the bind to the newly specified port, run the following command:
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root@server-02:~# systemctl restart ssh |
Verify the bind to the new port
Run the following commmand to verify the bind:
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root@server-02:~# ss -tlpn| grep ssh LISTEN 0 128 0.0.0.0:2021 0.0.0.0:* users:(("sshd",pid=4227,fd=3)) LISTEN 0 128 [::]:2021 [::]:* users:(("sshd",pid=4227,fd=4)) root@server-02:~# netstat -tlpn| grep ssh tcp 0 0 0.0.0.0:2021 0.0.0.0:* LISTEN 4227/sshd: /usr/sbi tcp6 0 0 :::2021 :::* LISTEN 4227/sshd: /usr/sbi |
Verify the change by logging in
Attempt to log into the server with Secure Shell (SSH). You should see the following response:
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ssh: connect to host 104.239.174.157 port 22: Connection refused |
Now, SSH by using the -p <Port Number> option. This should work:
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ssh root@104.239.174.157 -p 2021 root@104.239.174.157's password: |