What is Well Known Ports?

Understanding Well Known Ports

Ports in the range from 0 through 1023. Well-known ports are reserved port numbers in the lowest range 0-1023 that are assigned by IANA for common standard services like HTTP port 80 HTTPS port 443 SSH port 22 FTP port 21 and other fundamental network protocols. These ports are typically restricted to privileged processes on Unix-like systems and represent core internet services. Port assignments are documented in the IANA Service Name and Port Number Registry following guidelines in RFC 6335. Organizations secure well-known ports through firewall rules service restrictions access controls and network monitoring. For example an enterprise might implement security controls for well-known ports including restricting unnecessary services running on standard ports configuring firewalls to allow only required well-known ports implementing TLS for services using well-known ports monitoring for unusual traffic on these ports and conducting regular port scans to ensure no unauthorized services are running on well-known ports. Related terms Port numbers TCP/IP Registered ports Dynamic ports Firewall Network security Service registration Application layer protocol Port scanning Network protocols IANA registry.