The Well Known Ports are those in the range 0–1023. On Unix-like operating systems, binding a communications socket to a port in this range requires administrative/root privileges. The following is the list of such ports.
7/TCP,UDP Echo
20/TCP FTP - data
21/TCP FTP—control (command)
22/TCP,UDP Secure Shell (SSH)—used for secure logins, file transfers (scp, sftp) and port forwarding
23/TCP Telnet protocol—unencrypted text communications
25/TCP Simple Mail Transfer Protocol (SMTP)—used for e-mail routing between mail servers
43/TCP WHOIS protocol
53/TCP,UDP Domain Name System (DNS)
57/TCP MTP, Mail Transfer Protocol
69/UDP Trivial File Transfer Protocol (TFTP)
70/TCP Gopher protocol
79/TCP Finger protocol
80/TCP Hypertext Transfer Protocol (HTTP)
88/TCP Kerberos—authentication system
107/TCP Remote TELNET Service[6] protocol
109/TCP Post Office Protocol 2 (POP2)
110/TCP Post Office Protocol 3 (POP3)
111/TCP,UDP Sun Remote Procedure Call
115/TCP Simple File Transfer Protocol (SFTP)
118/TCP,UDP SQL (Structured Query Language) Services
123/UDP Network Time Protocol (NTP)—used for time synchronization
143/TCP,UDP Internet Message Access Protocol (IMAP)—retrieving, synchronizing e-mail messages
156/TCP,UDP SQL Service
161/TCP,UDP Simple Network Management Protocol (SNMP)
162/TCP,UDP Simple Network Management Protocol Trap (SNMPTRAP)[9]
170/TCP Print-srv, Network PostScript
177/TCP,UDP X Display Manager Control Protocol (XDMCP)
194/UDP IRC (Internet Relay Chat)
220/TCP,UDP IMAP, Interactive Mail Access Protocol, version 3
389/TCP,UDP Lightweight Directory Access Protocol (LDAP)
443/TCP,UDP Hypertext Transfer Protocol over TLS/SSL (HTTPS)
445/TCP Microsoft-DS Active Directory, Windows shares
445/UDP Microsoft-DS SMB file sharing
465/TCP SMTP over SSL
513/UDP Who
554/TCP,UDP Real Time Streaming Protocol (RTSP)
636/TCP,UDP Lightweight Directory Access Protocol over TLS/SSL (LDAPS)
873/TCP Rsync file synchronisation protocol
989/TCP,UDP FTPS Protocol (data): FTP over TLS/SSL
990/TCP,UDP FTPS Protocol (control): FTP over TLS/SSL
992/TCP,UDP TELNET protocol over TLS/SSL
993/TCP Internet Message Access Protocol over SSL (IMAPS)
995/TCP Post Office Protocol 3 over TLS/SSL (POP3S)
