There are hundreds of hundreds of ports associated with specific protocols. You only need to know most common handful of ports for your professional certification exams and job interview.
| Protocol | General Port | Secure Port | TCP/UDP |
|---|---|---|---|
| FTP | 21 | 989/990 | TCP |
| SSH/SEP | 22 | 22 | TCP/UDP |
| Telnet | 23 | NA | TCP/UDP |
| SMTP | 25 | 587 or 465 | TCP |
| DNS | 53 | NA | TCP/UDP |
| DHCP | server 87 clinet 68 |
NA | TCP/UDP |
| HTTP | 80 | 443 | TCP |
| POP3 | 110 | 995 | TCP |
| NetBIOS | 143 | 993 | TCP |
| SNMP | 161 | NA | UDP |
| SNMPTRAP | 162 | NA | TCP/UDP |
| SLP | 427 | NA | TCP/UDP |
| AFP | 548 | NA | TCP |
| RDP | 3389 | NA | TCP/UDP |
Other common ports you should know
| Protocol | General Port | Secure Port | TCP/UDP |
|---|---|---|---|
| Echo | 7 | NA | UDP |
| Chargen | 19 | NA | TCP/UDP |
| WINS Replication | 42 | NA | – |
| WHOIS | 43 | NA | TCP |
| TACACS | 49 | NA | TCP/UDP |
| TFTP | 69 | NA | UDP |
| Gopher | 70 | NA | TCP |
| Finger | 79 | NA | TCP/UDP |
| Kerberos | 88 | NA | UDP/TCP |
| MS Exchange | 103 | NA | TCP/UDP |
| Ident | 113 | NA | UDP |
| NTP | 123 | NA | UDP |
| IMAP4 | 143 | NA | TCP |
| BGP | 179 | NA | TCP |
| DHCPv6 | 546 or 547 | NA | UDP |
| RADIUS | 1812 or 1813 | NA | TCP/UDP |
| MySQL | 3306 | NA | TCP |
| Microsoft SQL | 1433 or 1434 | NA | TCP |
| PostgreSQL | 5432 | NA | TCP |