Reference tool
Network Port Reference
Look up common TCP and UDP ports and the services that use them, a fast reference for writing firewall rules and troubleshooting connections.
Network Port Reference
Showing 49 of 49 entries
| Port | Protocol | Service | Description | Category |
|---|---|---|---|---|
| 20 | TCP | FTP Data | FTP data transfer channel. | File Transfer |
| 21 | TCP | FTP Control | FTP command/control channel. Use SFTP (22) or FTPS instead. | File Transfer |
| 22 | TCP | SSH / SFTP | Secure Shell remote access and SFTP file transfer. | Remote Access |
| 23 | TCP | Telnet | Unencrypted remote terminal. Deprecated, use SSH. | Remote Access |
| 25 | TCP | SMTP | Server-to-server email delivery (outbound MTA). Often blocked by ISPs. | |
| 110 | TCP | POP3 | Post Office Protocol v3. Downloads mail from server. | |
| 143 | TCP | IMAP | Internet Message Access Protocol. Syncs mail with server. | |
| 465 | TCP | SMTPS | SMTP over TLS/SSL (legacy; use 587). | |
| 587 | TCP | SMTP Submission | Authenticated email submission (STARTTLS). Preferred for clients. | |
| 993 | TCP | IMAPS | IMAP over TLS/SSL. | |
| 995 | TCP | POP3S | POP3 over TLS/SSL. | |
| 80 | TCP | HTTP | Unencrypted web traffic. Redirect all to HTTPS (443). | Web |
| 443 | TCP | HTTPS | HTTP over TLS/SSL. Standard secure web. | Web |
| 8080 | TCP | HTTP Alt | Alternate HTTP port, commonly used by dev/proxy servers. | Web |
| 8443 | TCP | HTTPS Alt | Alternate HTTPS port, used by some web applications. | Web |
| 53 | TCP/UDP | DNS | Domain Name System queries (UDP standard; TCP for large responses). | Network |
| 67 | UDP | DHCP Server | DHCP server listens on this port. | Network |
| 68 | UDP | DHCP Client | DHCP client port. | Network |
| 161 | UDP | SNMP | Simple Network Management Protocol for device monitoring. | Network |
| 162 | UDP | SNMP Trap | SNMP trap receiver. | Network |
| 123 | UDP | NTP | Network Time Protocol, clock synchronization. | Network |
| 3389 | TCP | RDP | Windows Remote Desktop Protocol. Restrict to VPN, never expose publicly. | Remote Access |
| 5900 | TCP | VNC | Virtual Network Computing remote desktop. | Remote Access |
| 1194 | UDP | OpenVPN | OpenVPN default UDP port. | VPN |
| 1723 | TCP | PPTP VPN | Point-to-Point Tunneling Protocol. Deprecated, use WireGuard/IKEv2. | VPN |
| 4500 | UDP | IKEv2 NAT-T | IKEv2 VPN NAT traversal. | VPN |
| 500 | UDP | IKE/IPsec | IPsec Internet Key Exchange. | VPN |
| 51820 | UDP | WireGuard | WireGuard VPN default port (configurable). | VPN |
| 1433 | TCP | MS SQL Server | Microsoft SQL Server. Never expose directly to internet. | Database |
| 1521 | TCP | Oracle DB | Oracle Database listener. | Database |
| 3306 | TCP | MySQL / MariaDB | MySQL and MariaDB default port. | Database |
| 5432 | TCP | PostgreSQL | PostgreSQL default port. | Database |
| 6379 | TCP | Redis | Redis in-memory data store. | Database |
| 27017 | TCP | MongoDB | MongoDB default port. | Database |
| 389 | TCP/UDP | LDAP | Lightweight Directory Access Protocol (unencrypted). | Directory |
| 636 | TCP | LDAPS | LDAP over TLS/SSL. | Directory |
| 88 | TCP/UDP | Kerberos | Kerberos authentication (Active Directory). | Directory |
| 445 | TCP | SMB / CIFS | Windows file sharing. High-value attack target, restrict to LAN. | Directory |
| 135 | TCP | MS RPC | Microsoft RPC endpoint mapper. | Directory |
| 9100 | TCP | Raw Printing | Network printer raw data port (JetDirect). | Printing |
| 515 | TCP | LPD/LPR | Line Printer Daemon protocol. | Printing |
| 631 | TCP | IPP / CUPS | Internet Printing Protocol. | Printing |
| 5060 | TCP/UDP | SIP | Session Initiation Protocol for VoIP signaling. | VoIP |
| 5061 | TCP | SIP TLS | SIP over TLS. | VoIP |
| 3478 | UDP | STUN/TURN | NAT traversal for WebRTC and VoIP. | VoIP |
| 514 | UDP | Syslog | Standard syslog UDP receiver. | Monitoring |
| 6514 | TCP | Syslog TLS | Syslog over TLS. | Monitoring |
| 9090 | TCP | Prometheus | Prometheus metrics scraping server. | Monitoring |
| 443 | TCP | M365 / Azure | All Microsoft 365 and Azure traffic uses port 443 over HTTPS. | Cloud |
Frequently asked questions
Which ports should always be blocked at the firewall perimeter?
At a minimum, block inbound access to RDP (3389), SMB (445), NetBIOS (135–139), Telnet (23), and all database ports (1433, 3306, 5432) from the internet. These are among the highest-value targets for ransomware and exploitation. Any administrative port, RDP, SSH (22), management interfaces, should be restricted to known IP ranges or accessible only over VPN. Outbound, block direct SMTP (port 25) from end-user machines to prevent spam relay.
What is the difference between TCP and UDP ports?
TCP (Transmission Control Protocol) provides reliable, ordered, and error-checked delivery. It is used by protocols where data integrity matters: web (80/443), email (25/587/993), databases, and SSH. UDP (User Datagram Protocol) is connectionless and faster but does not guarantee delivery or order. It is used by latency-sensitive applications like DNS (53), VoIP/SIP (5060), NTP (123), and video streaming. Some services use both, DNS uses UDP for standard queries and TCP for large responses or zone transfers.
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