Port

Port 389

Conventionally used by LDAP. Port assignments are conventions, so confirm the actual listener before you write a rule around this number.

TCP · UDPEncrypted: Optional

Protocols on this port

LDAP

Directory queries and binds

Security: Use LDAPS or StartTLS; enforce signing and channel binding

TCP / UDP · Encrypted: Optional

Where this port appears in the documentation

Active Directory

Microsoft's on premises directory service, providing authentication, authorisation, policy and object management for Windows environments.

LDAP

Lightweight Directory Access Protocol is the query and update protocol for directory services, running on TCP/389 or TCP/636 for LDAPS.

Exposure guidance

Decide reachability from the identity of the caller, not from the port number. If the service on this port carries credentials or administrative control, restrict it to an administrative network, require strong authentication, and log every session that reaches it.

Nearby ports

Port 162 Port 443

In the knowledge graph

Open the interactive map centred on this entity to see everything it connects to and travel outwards from there.

Explore port 389 in the knowledge graph