How to Modify the Login Port of a US Server

Securing your server’s login ports is a critical aspect of maintaining robust security for your server hosting infrastructure. In today’s increasingly sophisticated cyber threat landscape, default server ports have become prime targets for malicious actors. By modifying default login ports, you significantly reduce the risk of automated attacks and unauthorized access attempts. This comprehensive guide will walk you through the process of changing them on both Windows and Linux servers, ensuring your systems remain protected against potential threats.

Understanding Server Port Security

Default ports like 22 for SSH and 3389 for RDP are common targets for cybercriminals. These ports face constant scanning and brute-force attempts from automated bots, with some servers receiving thousands of login attempts daily. While changing default ports isn’t a complete security solution, it serves as an effective first line of defense through security by obscurity. This practice, combined with other security measures, can dramatically reduce your server’s attack surface.

Statistical analysis shows that servers using default ports experience up to 95% more unauthorized access attempts compared to those using custom ports. This significant difference emphasizes the importance of port modification as part of a comprehensive security strategy.

Pre-modification Checklist

Before initiating any port changes, it’s crucial to prepare thoroughly to prevent potential system lockouts or service disruptions. Here’s a detailed checklist of essential preparations:

• Create comprehensive backups of all configuration files
  • SSH configuration files
  • Firewall rules
  • System settings
• Verify root or administrative access credentials
  • Test sudo privileges
  • Confirm administrative passwords
• Document existing port configurations
  • Current port numbers
  • Active services
  • Dependencies
• Prepare updated firewall rules
  • New port allowances
  • IP restrictions
• Establish backup connection methods
  • Alternative SSH ports
  • Emergency console access

Modifying SSH Port on Linux Systems

Linux servers typically use SSH for remote access. Changing it requires careful modification of several system components. Follow these detailed steps:

# Step 1: Access SSH configuration with backup
sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.backup
sudo nano /etc/ssh/sshd_config

# Step 2: Locate and modify port (choose a port between 1024 and 65535)
# Comment out old port
#Port 22
# Add new port
Port 2022

# Step 3: Configure SELinux (if enabled)
semanage port -a -t ssh_port_t -p tcp 2022

# Step 4: Update firewall rules
sudo ufw allow 2022/tcp
sudo ufw deny 22/tcp

# Step 5: Restart SSH service safely
sudo systemctl restart sshd
sudo systemctl status sshd  # Verify service is running
        

After executing these commands, maintain your current session while testing the new configuration. This approach ensures you don’t lose access if something goes wrong.

Changing RDP Port on Windows Servers

Windows Remote Desktop Protocol (RDP) port modification requires registry changes and proper firewall configuration. Here’s the detailed process:

# Step 1: Create Registry Backup
reg export "HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp" rdp_backup.reg

# Step 2: Modify Registry Settings
# Navigate to:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp

# Step 3: Change PortNumber value
# Default is 3389 (decimal)
# Example new port: 3390

# Step 4: Configure Windows Firewall
New-NetFirewallRule -DisplayName "RDP-Custom" -Direction Inbound -Protocol TCP -LocalPort 3390 -Action Allow
Remove-NetFirewallRule -DisplayName "Remote Desktop (TCP-In)"  # Optional: remove old rule
        

Verification and Testing Procedures

Proper verification is crucial to ensure continued server access. Follow this comprehensive testing protocol:

• Maintain current session while testing:
  • Keep existing connection active
  • Open new session on new port
  • Verify functionality before closing original session
• Firewall verification:
  • Check incoming and outgoing rules
  • Verify port accessibility
  • Test from different networks
• System logs monitoring:
  • Check for error messages
  • Monitor authentication attempts
  • Verify successful connections

Advanced Security Enhancements

Beyond port changes, implement these advanced security measures to create a robust defense system:

• Port knocking configuration:
  • Sequential port activation
  • Dynamic port sequences
  • Time-based rules
• SSH key authentication:
  • 4096-bit RSA keys
  • Password-protected key pairs
  • Regular key rotation
• Access restrictions:
  • IP whitelisting
  • Geographic restrictions
  • Time-based access controls

Remember that server security is an ongoing process. Regular audits, updates, and monitoring are essential components of maintaining a secure hosting environment. By implementing the strategies outlined in this guide, you’ve taken a significant step toward protecting your infrastructure from potential threats.