| Protocol | Port |
|---|---|
| FTP: File Transport Protocol | 20, 21 |
| SSH: Secure Shell | 22 |
| SFTP: Secure File Transport Protocol, which uses SSH | 22 |
| SCP: Secure Copy which uses SSH | 22 |
| Telnet | 23 |
| SMTP: Simple Mail Transport Protocol | 25 |
| TACACS: Terminal Access Controller Access-Control System | 49 |
| DNS: Domain Name System | 53 |
| DHCP: Dynamic Host Configuration Protocol | 67, 68 |
| TFTP: Trivial File Transport Protocol | 69 |
| HTTP: Hypertext Transfer Protocol | 80 |
| HTTPS: Hypertext Transfer Protocol Secure | 443 |
| SSL VPN: Secure Sockets Layer virtual private network | 443 |
| Kerberos | 88 |
| POP3: Post Office Protocol version 3 | 110 |
| NNTP: Network News Transfer Protocol | 119 |
| IMAP4: Internet message access protocol version 4 | 143 |
| SNMP: Simple Network Management Protocol | 161 |
| SNMP Trap: Simple Network Management Protocol Trap | 162 |
| LDAP: Lightweight Directory Access Protocol | 389 |
| ISAKMP (VPN): Internet Security Association and Key Management Protocol (virtual private network) | 500 |
| Syslog | 514 |
| L2TP: Layer 2 Tunneling Protocol | 1701 |
| PPTP: Point-to-Point Tunneling Protocol | 1723 |
| RDP: Remote Desktop Protocol | 3389 |