Port 389: LDAP
Port 389 is LDAP, used to query directories like Active Directory and OpenLDAP for users and groups. The encrypted form, LDAPS, uses port 636.
TCP/UDPAuthenticationUnencrypted by defaultIANA assigned
| Port number | 389 |
|---|---|
| Service | Lightweight Directory Access Protocol |
| Protocol | TCP/UDP |
| Category | Authentication |
| Default encryption | No |
Security note. Port 389 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 389 used for?
Port 389 is LDAP, used to query directories like Active Directory and OpenLDAP for users and groups. The encrypted form, LDAPS, uses port 636.
Is port 389 TCP or UDP?
Port 389 (LDAP) uses TCP/UDP.
Is port 389 secure?
Port 389 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 389 on my firewall?
Only if you specifically need LDAP. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.