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Port Reference Guide
A comprehensive reference of common network ports, their services, protocols, and security risk levels. Use this to understand which ports should be open or closed on your systems.
49 of 49 ports
| Port | Protocol | Service | Description | Risk |
|---|---|---|---|---|
| 20 | TCP | FTP (data) | File Transfer Protocol — data transfer channel. | high |
| 21 | TCP | FTP (control) | File Transfer Protocol — command/control channel. Transmits credentials in plaintext. | high |
| 22 | TCP | SSH | Secure Shell — encrypted remote administration. | low |
| 23 | TCP | Telnet | Unencrypted remote administration. Deprecated and dangerous. | high |
| 25 | TCP | SMTP | Simple Mail Transfer Protocol — email sending. | medium |
| 53 | TCP/UDP | DNS | Domain Name System — name resolution. | medium |
| 67 | UDP | DHCP (server) | Dynamic Host Configuration Protocol — IP assignment. | medium |
| 68 | UDP | DHCP (client) | DHCP client port. | low |
| 80 | TCP | HTTP | Hypertext Transfer Protocol — unencrypted web traffic. | medium |
| 110 | TCP | POP3 | Post Office Protocol v3 — email retrieval (unencrypted). | high |
| 119 | TCP | NNTP | Network News Transfer Protocol. | medium |
| 123 | UDP | NTP | Network Time Protocol — time synchronization. | low |
| 135 | TCP | MS-RPC | Microsoft Remote Procedure Call endpoint mapper. | high |
| 137 | UDP | NetBIOS NS | NetBIOS Name Service. | high |
| 139 | TCP | NetBIOS SSN | NetBIOS Session Service. | high |
| 143 | TCP | IMAP | Internet Message Access Protocol — email retrieval. | medium |
| 161 | UDP | SNMP | Simple Network Management Protocol — network device monitoring. | high |
| 194 | TCP | IRC | Internet Relay Chat. | medium |
| 389 | TCP | LDAP | Lightweight Directory Access Protocol. | medium |
| 443 | TCP | HTTPS | HTTP over TLS/SSL — encrypted web traffic. | low |
| 445 | TCP | SMB | Server Message Block — Windows file/printer sharing. Common ransomware vector. | high |
| 465 | TCP | SMTPS | SMTP over TLS — secure email sending. | low |
| 500 | UDP | IKE / IPsec | Internet Key Exchange — VPN negotiation. | low |
| 514 | UDP | Syslog | System logging protocol. | medium |
| 587 | TCP | SMTP (submission) | Email submission with STARTTLS. | low |
| 636 | TCP | LDAPS | LDAP over TLS/SSL. | low |
| 993 | TCP | IMAPS | IMAP over TLS/SSL. | low |
| 995 | TCP | POP3S | POP3 over TLS/SSL. | low |
| 1080 | TCP | SOCKS | SOCKS proxy protocol. | medium |
| 1194 | UDP | OpenVPN | OpenVPN default port. | low |
| 1433 | TCP | MS SQL | Microsoft SQL Server. | high |
| 1521 | TCP | Oracle DB | Oracle database default listener. | high |
| 2049 | TCP/UDP | NFS | Network File System. | high |
| 2083 | TCP | cPanel SSL | cPanel/WHM over HTTPS. | low |
| 3306 | TCP | MySQL | MySQL / MariaDB database. Should never be publicly exposed. | high |
| 3389 | TCP | RDP | Remote Desktop Protocol. High-value target for brute force. | high |
| 4443 | TCP | HTTPS alt | Alternate HTTPS port. | low |
| 5432 | TCP | PostgreSQL | PostgreSQL database default port. | high |
| 5900 | TCP | VNC | Virtual Network Computing — remote desktop. | high |
| 5985 | TCP | WinRM (HTTP) | Windows Remote Management over HTTP. | high |
| 5986 | TCP | WinRM (HTTPS) | Windows Remote Management over HTTPS. | medium |
| 6379 | TCP | Redis | Redis in-memory database. Often publicly exposed without auth. | high |
| 6443 | TCP | Kubernetes API | Kubernetes API server. | high |
| 8080 | TCP | HTTP alt | Alternate HTTP port, commonly used by proxies and dev servers. | medium |
| 8443 | TCP | HTTPS alt | Alternate HTTPS port. | low |
| 8888 | TCP | Jupyter | Jupyter Notebook default port. | high |
| 9200 | TCP | Elasticsearch | Elasticsearch REST API. Often publicly exposed without auth. | high |
| 27017 | TCP | MongoDB | MongoDB default port. Commonly found exposed publicly. | high |
| 51820 | UDP | WireGuard | WireGuard VPN default port. | low |