Knowledge graph
Port index
Each port has its own page recording the protocols that conventionally use it, the transport, whether traffic is encrypted and where the exposure decision is documented. Port numbers are conventions, so always confirm what is actually listening.
43 ports
| Port | Protocols | Transport | Encrypted |
|---|---|---|---|
| 21 | FTP | TCP | No |
| 22 | SFTP, SSH | TCP | Yes |
| 23 | Telnet | TCP | No |
| 25 | SMTP | TCP | Optional |
| 53 | DNS | TCP, UDP | No |
| 67 | DHCP | UDP | No |
| 68 | DHCP | UDP | No |
| 80 | HTTP | TCP | No |
| 88 | Kerberos | TCP, UDP | Yes |
| 110 | POP3 / POP3S | TCP | Optional |
| 123 | NTP | UDP | No |
| 143 | IMAP / IMAPS | TCP | Optional |
| 161 | SNMP | UDP | Optional |
| 162 | SNMP | UDP | Optional |
| 389 | LDAP | TCP, UDP | Optional |
| 443 | HTTPS | (QUIC), TCP, UDP | Yes |
| 445 | SMB | TCP | Optional |
| 464 | Kerberos kpasswd | TCP, UDP | Yes |
| 500 | IPsec IKE | UDP | Yes |
| 514 | Syslog | TCP, UDP | Optional |
| 546 | DHCPv6 | UDP | No |
| 547 | DHCPv6 | UDP | No |
| 587 | SMTP Submission | TCP | Yes |
| 636 | LDAPS | TCP | Yes |
| 853 | DNS over TLS | TCP | Yes |
| 990 | FTPS | TCP | Yes |
| 993 | IMAP / IMAPS | TCP | Optional |
| 995 | POP3 / POP3S | TCP | Optional |
| 1433 | Microsoft SQL Server | TCP | Optional |
| 1521 | Oracle TNS | TCP | Optional |
| 1812 | RADIUS | UDP | Optional |
| 1813 | RADIUS | UDP | Optional |
| 3268 | Global Catalog | TCP | Optional |
| 3269 | Global Catalog | TCP | Optional |
| 3306 | MySQL / MariaDB | TCP | Optional |
| 3389 | RDP | TCP, UDP | Yes |
| 4500 | IPsec NAT T | UDP | Yes |
| 5432 | PostgreSQL | TCP | Optional |
| 5985 | WinRM | TCP | Optional |
| 5986 | WinRM | TCP | Optional |
| 6379 | Redis | TCP | Optional |
| 6443 | Kubernetes API | TCP | Yes |
| 51820 | WireGuard | UDP | Yes |
Reading a port list
A port number tells you what a service is meant to be, never what it is. Confirm the listener with a banner grab or an inventory query before writing a firewall rule around it, and treat any management port reachable from a user network as an exposure to close rather than a configuration to document.