Appendix B: Well-known Port Numbers
The port numbers are divided into three ranges: the Well Known Ports, the Registered Ports, and the Dynamic and/or Private Ports. The Well Known Ports are those from 0 through 1023. The Registered Ports are those from 1024 through 49151. The Dynamic and/or Private Ports are those from 49152 through 65535.
The Well Known Ports are assigned by the IANA, and on most systems, can only be used by system processes or by programs executed by privileged users. Table
Table B-1 Well-known port numbers
| Port number |
| Protocol |
|
|
| TCP/UDP |
|
| 21 |
| FTP (File Transfer Protocol) |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 22 |
| SSH (Secure SHell) |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 23 |
| Telnet |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 25 |
| SMTP (Simple Mail Transfer Protocol) |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 37 |
| Time |
|
| TCP, UDP |
| |
|
|
|
|
|
|
|
| |
| 39 |
| RLP (Resource Location Protocol) |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 49 |
| TACACS, TACACS+ |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 53 |
| DNS |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 67 |
| BOOTP server |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 68 |
| BOOTP client |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 69 |
| TFTP |
|
| UDP |
| |
|
|
|
|
|
|
|
| |
| 70 |
| Gopher |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 79 |
| Finger |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 80 |
| HTTP |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 110 |
| POP3 |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 119 |
| NNTP (Network News Transfer Protocol) |
|
| TCP |
| |
|
|
|
|
|
|
|
| |
| 161/162 |
| SNMP |
|
| UDP |
| |
|
|
|
|
|
|
|
|
|
43