List of TCP/IP UDP Ports and Protocols
Here we are listing out important well-known ports or system ports with protocol. Port number can vary from 0-65535 so total number of ports are 65536. The Internet Assigned Numbers Authority (IANA) maintains official assignments of port numbers for specific uses. However, many unofficial uses of both well-known and registered port numbers occur in practice.

| Protocol | Port Numbers | ||
| FTP | 20/21 | ||
| SSH | 22 | ||
| Telnet | 23 | ||
| SMTP | 25 | ||
| DNS | 53 | ||
| DHCP | 67/68 | ||
| TFTP | 69 | ||
| HTTP | 80 | ||
| POP v3 | 110 | ||
| NTP | 123 | ||
| NetBios | 137/138/139 | ||
| IMAP | 143 | ||
| SNMP | 161/162 | ||
| LDAP | 389 | ||
| HTTPS | 443 | ||
| LDAPS | 636 | ||
| POP3 -SSL | 995 | ||
| FTP over TLS/SSL | 989/990 | ||
| Remote Desktop | 3389 | ||
| Previously Netstat | 15 | ||
| Host Name Server | 42 | ||
| Kerberos | 88 | ||
| AD Global Catalog | 3268 | ||
| AD Global Catalog SSL | 3269 |



