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The Ultimate Guide to Default SSH Ports Print denne artikel
What is SSH Port : What You Need to Know and How to Change Yours Safely
Secure Shell (SSH) is an essential tool for managing servers securely, but many new users are often unaware of its default settings and the importance of customizing them. In this guide, we will cover everything you need to know about the default SSH port, why you might want to change it, and how to do so across various Linux distributions to enhance your security.
1. What is the Default SSH Port Number?
SSH connections typically operate over TCP port 22. This port is designated as the default for SSH services by the Internet Assigned Numbers Authority (IANA). Most SSH servers, including OpenSSH, listen for incoming connections on this port. Because it's the standard port, malicious actors often scan for it in their attempts to gain unauthorized access, making it essential for system admins to consider security measures.
2. Why Change the Default SSH Port?
Changing the default SSH port can significantly improve your server’s security posture. Here are some compelling reasons to consider making the switch:
- Reduce Automated Attacks: Many attackers use automated tools to scan for open ports, including port 22. Changing the port can significantly reduce the number of brute force attempts on your SSH service.
- Enhanced Security: By employing “security through obscurity,” you make it harder for unauthorized users to find your SSH service.
- Custom Port Policies: Some organizations have specific security policies that require the use of custom ports for non-standard services.
While changing the default SSH port isn’t a foolproof solution, it is an effective way to add another layer of defense.
3. How to Change the Default SSH Port
Changing your SSH port varies slightly across different Linux distributions. Here’s a detailed step-by-step guide tailored for the major distributions.
For Ubuntu/Debian-based Systems:
-
Open the SSH Configuration File:
-
sudo nano /etc/ssh/sshd_config -
Find the Port Line:
Look for a line that reads:
#Port 22Un-comment this line and change the port number to your desired value (e.g., 2222):
-
Port 2222 -
Adjust Your Firewall:
If you’re using UFW (Uncomplicated Firewall), add the new port: -
sudo ufw allow 2222/tcp -
Restart the SSH Service:
-
sudo systemctl restart ssh -
Test Your New Connection:
Open a new terminal and attempt to connect using the new port:
-
ssh -p 2222 username@your_server_ip
For RHEL/CentOS/Fedora:
-
Edit the SSH Configuration File:
-
sudo nano /etc/ssh/sshd_config -
Find the Port Line:
Similar to Ubuntu, search for:
#Port 22Remove the comment and change the port number:
-
Port 2222 -
Adjust Your Firewall:
If you’re using firewalld: -
sudo firewall-cmd --permanent --zone=public --add-port=2222/tcp sudo firewall-cmd --reload -
Restart the SSH Service:
-
sudo systemctl restart sshd -
Test Your New Connection:
Use the following command to connect:
-
ssh -p 2222 username@your_server_ip
For Arch Linux:
-
Open the SSH Config File:
-
sudo nano /etc/ssh/sshd_config -
Update the Port Line:
Locate the line with:
#Port 22Change it to your preferred port:
-
Port 2222 -
Configure the Firewall:
For iptables, do: -
sudo iptables -A INPUT -p tcp --dport 2222 -j ACCEPT -
Restart the SSH Service:
-
sudo systemctl restart sshd -
Validate the Change:
Connect using:
-
ssh -p 2222 username@your_server_ip
Important Note:
Always ensure that your firewall rules allow traffic on the new port before you restart the SSH service. If you get locked out, you may face difficulties connecting to the server.
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4. FAQ
Is it safe to change the SSH port?
Yes, changing the SSH port is a common practice to enhance security. However, it's not a silver bullet—combine it with other security measures like using SSH keys, disabling root login, and employing fail2ban.
What if I forget the new SSH port?
Make sure you document your new SSH port or create a backup of the original configuration. If you forget, you might need console access to the server to revert the changes.
Can I use any port I want?
Technically, you can use any port between 1 and 65535. However, it’s advisable to avoid ports below 1024 as they are often reserved for standard protocols.
Do I need to restart the server when I change the SSH port?
No, you only need to restart the SSH service, not the entire server.
Changing the default SSH port is a simple yet effective way to bolster your server's defenses. By making this change, combined with other security measures, you can significantly reduce your risk of unauthorized access. Follow this guide, choose a unique port, and take your server security to the next level!
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