NETCUE TECHNOLOGY: We Rescue Networks

Port Number Lookup

Look up port numbers and their associated network services and protocols.

Port Information:

Common Port Numbers

Port Protocol Service Description
20, 21 TCP FTP File Transfer Protocol
22 TCP SSH Secure Shell
23 TCP Telnet Telnet remote login service
25 TCP SMTP Simple Mail Transfer Protocol
53 TCP/UDP DNS Domain Name System
80 TCP HTTP HyperText Transfer Protocol
110 TCP POP3 Post Office Protocol v3
143 TCP IMAP Internet Message Access Protocol
443 TCP HTTPS HTTP Secure
993 TCP IMAPS IMAP over SSL/TLS
995 TCP POP3S POP3 over SSL/TLS

Port Ranges

Port Range Usage Description
0-1023 Well-known ports Assigned by IANA for standard services
1024-49151 Registered ports Assigned by IANA for specific services
49152-65535 Dynamic/Private ports Available for private use

Port Security Considerations

  • Open Ports: Unnecessary open ports increase security risk
  • Firewall Rules: Configure firewalls to only allow required ports
  • Port Scanning: Regular port scans help identify vulnerabilities
  • Default Ports: Change default ports for sensitive services
  • Port Forwarding: Only forward ports that are absolutely necessary

IANA Port Assignments

The Internet Assigned Numbers Authority (IANA) maintains the official list of port number assignments. This database is regularly updated and contains:

  • Well-known ports (0-1023)
  • Registered ports (1024-49151)
  • Dynamic ports (49152-65535)

You can find the complete list at: IANA Service Name and Transport Protocol Port Number Registry

TCP vs UDP

TCP (Transmission Control Protocol)

  • Connection-oriented
  • Reliable data delivery
  • Error checking and correction
  • Ordered data transmission
  • Slower but more reliable

UDP (User Datagram Protocol)

  • Connectionless
  • Unreliable data delivery
  • No error checking
  • Faster but less reliable
  • Used for real-time applications