Reasons for Using Non-Standard Transport Layer Ports

Transport Layer port numbers are used for specific services, using either TCP or UDP. These port numbers are standardized for particular protocols and network functions. However, network administrators may choose to use non-standard ports instead of well-known default ports for several important operational and security reasons:

Security through Obscurity

  • Reduces service visibility to automated scanning tools
  • Makes it harder for attackers targeting standard port numbers
  • Should be used as a supplementary security measure, not primary defense

Multiple Service Hosting

  • Enables running multiple instances of similar services on one server
  • Example: Running two web services on ports 80 and 8000
  • Allows efficient use of server resources without conflicts

Policy Bypass

  • Can circumvent network restrictions blocking standard ports
  • Useful for legitimate services affected by overly restrictive policies
  • Should be implemented with proper authorization and documentation

Conclusion

When you change port numbers, keep the following in mind:

  • Document all non-standard port usage
  • Ensure proper firewall rules are in place
  • Consider the impact on monitoring and troubleshooting
  • Maintain an updated port inventory

https://networklessons.com/network-fundamentals/introduction-to-tcp-and-udp