Common network
ports and protocols.
A quick reference for common infrastructure services. Search the curated list by port, protocol or service name. This page does not scan a device or test a connection.
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| Port | Transport | Common association | Operational note |
|---|---|---|---|
| 20–21 | TCP | FTP data / control | Legacy file transfer; prefer a protected alternative such as SFTP when appropriate. |
| 22 | TCP | SSH | Remote shell and secure file transfer; restrict administrative access. |
| 25 | TCP | SMTP relay | Mail transfer between servers; client submission commonly uses other ports. |
| 53 | TCP, UDP | DNS | UDP is common for queries; TCP is also needed for some responses and operations. |
| 67 | UDP | DHCP server | Server-side DHCPv4 traffic on a local network. |
| 68 | UDP | DHCP client | Client-side DHCPv4 traffic on a local network. |
| 80 | TCP | HTTP | Web traffic without TLS at the transport layer; sites commonly redirect to HTTPS. |
| 88 | TCP, UDP | Kerberos | Authentication service; actual reachability depends on the directory environment. |
| 110 | TCP | POP3 | Legacy mail retrieval; use a protected configuration where supported. |
| 123 | UDP | NTP | Network time synchronization. |
| 143 | TCP | IMAP | Mail access; secure variants are commonly preferred. |
| 161 | UDP | SNMP | Device management and monitoring; do not expose broadly to untrusted networks. |
| 389 | TCP, UDP | LDAP | Directory access; evaluate transport protection and directory policy. |
| 443 | TCP | HTTPS | Web traffic protected with TLS. |
| 443 | UDP | HTTP/3 over QUIC | Modern web traffic may use UDP 443 when the client and server support HTTP/3. |
| 445 | TCP | SMB file sharing | Keep file-sharing access on trusted networks; block direct exposure to the public internet. |
| 465 | TCP | SMTP submission with TLS | Mail submission with implicit TLS. |
| 500 | UDP | IPsec IKE | Key exchange for IPsec VPNs. |
| 514 | UDP | Syslog | Common syslog transport; deployments may use other protected transports. |
| 587 | TCP | Message submission | Mail-client submission; commonly paired with STARTTLS. |
| 636 | TCP | LDAP over TLS | Protected directory access when configured and trusted correctly. |
| 993 | TCP | IMAP over TLS | Protected mail access. |
| 995 | TCP | POP3 over TLS | Protected mail retrieval. |
| 1433 | TCP | Microsoft SQL Server | Common default instance listener; allow only required application paths. |
| 1434 | UDP | SQL Server Browser | May support discovery of named instances; review whether discovery is needed. |
| 3306 | TCP | MySQL | Common database listener; restrict to trusted application networks. |
| 3389 | TCP, UDP | Remote Desktop Protocol | Do not expose directly to the public internet; prefer an approved VPN or gateway. |
| 5432 | TCP | PostgreSQL | Common database listener; restrict to trusted application networks. |
| 5985 | TCP | WinRM over HTTP | Remote management endpoint; limit by network and policy, and prefer protected configurations. |
| 5986 | TCP | WinRM over HTTPS | Remote management over TLS; certificate and listener configuration still matter. |
| 8080 | TCP | Alternate HTTP / proxy | Often configured by the application or operator; verify the actual service. |
| 8443 | TCP | Alternate HTTPS | Often configured by the application or operator; verify the actual service. |
These are common defaults and examples, not a complete registry or firewall recommendation. Applications can use different ports, one port can host unrelated services, and a listening port alone does not prove a service is safe or reachable. Check your approved network diagrams, product configuration and security policy before changing access. For registered service and transport assignments, refer to the IANA Service Name and Port Number Registry. IANA also cautions operators to choose configurations based on their knowledge of the traffic, not merely whether a port is registered.
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