Value of number between 0-65535 that is part of every TCP or UDP packet.
TCP and UDP use 2 port numbers. The first port number is used by receiving system to determine the program that needs the data (like email server). The second number is a return address that the receiving system uses when it responds to the client. The second number is called ephemeral port number, quite large, arbitrary generation by client.
The internet consortium creators set up the first 1024 port numbers as well known numbers for specific use.
| Port Number | Protocol | Service Acronym | Service Name |
|---|---|---|---|
| 20 | TCP | FTP | File Transfer Protocol (Data Connection) |
| 21 | TCP | FTP | File Transfer Protocol (Control Connection) |
| 22 | TCP | SFTP | Secure Shell File Transfer Protocol (Control Connection) |
| 22 | TCP | SSH | Secure Shell |
| 23 | TCP | TELNET | Telnet |
| 25 | TCP | SMTP | Simple Mail Transfer Protocol |
| 33 | UDP/TCP | DSP | Display Support Protocol |
| 38 | UDP/TCP | RAP | Route Access Protocol |
| 39 | UDP/TCP | RLP | Resource Location Protocol |
| 53 | UDP/TCP | DNS | Domain Name System |
| 67 – 68 | UDP | DHCP | Dynamic Host Configuration Protocol |
| 69 | UDP/TCP | TFTP | Trivial File Transfer Protocol |
| 80 | TCP | HTTP | Hypertext Transfer Protocol |
| 110 | TCP | POP | Post Office Protocol |
| 123 | UDP | NTP | Network Time Protocol |
| 137 – 138 – 139 | UDP/TCP | NETBIOS/NETBT | NetBIOS/NetBT |
| 143 | TCP | IMAP | Internet Message Access Protocol |
| 161 – 162 | UDP | SNMP | Simple Network Management Protocol |
| 194 | TCP | IRC | Internet Relay Chat |
| 389 | TCP | LDAP | Lightweight Directory Access Protocol |
| 427 | UDP/TCP | SLP | Service Location Protocol |
| 443 | TCP | HTTPS | Hypertext Transfer Protocol over TLS/SSL |
| 445 | TCP | SMB/CIFS | Server Message Block/Common Internet File System |
| 514 | UDP | Syslog | System Logging Protocol |
| 548 | UDP/TCP | AFP | Apple File Services Protocol |
| 636 | TCP | LDAPS | Lightweight Directory Access Protocol over TLS/SSL |
| 587 | TCP | MSA/SMTPS | Message Submission Agent/SMTP Secure |
| 993 | TCP | IMAPS | Internet Message Access Protocol over TLS/SSL |
| 995 | TCP | POPS | Post Office Protocol over TLS/SSL |
| 1720 | TCP | H.323 | H.323 Call Control Signaling |
| 3389 | UDP/TCP | RDP | Remote Desktop Protocol |
| 5060 – 5061 | TCP | SIP | Session Initiation Protocol |