Port 3268: Global Catalog

Port 3268 is the Active Directory Global Catalog port, which lets applications search for objects across every domain in a forest instead of just one domain. It carries the same LDAP protocol as port 389, scoped to the forest-wide catalog.

TCPWindowsUnencrypted by defaultIANA assigned
Port number3268
ServiceMicrosoft Active Directory Global Catalog
ProtocolTCP
CategoryWindows
Default encryptionNo
Security note. Port 3268 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 3268 used for?

Port 3268 is the Active Directory Global Catalog port, which lets applications search for objects across every domain in a forest instead of just one domain. It carries the same LDAP protocol as port 389, scoped to the forest-wide catalog.

Is port 3268 TCP or UDP?

Port 3268 (Global Catalog) uses TCP.

Is port 3268 secure?

Port 3268 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.

Should I open port 3268 on my firewall?

Only if you specifically need Global Catalog. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.