Port 88: Kerberos
Port 88 is Kerberos, the ticket-based authentication protocol behind Active Directory logins. Clients contact the Key Distribution Center here to obtain and present tickets.
TCP/UDPAuthenticationUnencrypted by defaultIANA assigned
| Port number | 88 |
|---|---|
| Service | Kerberos authentication |
| Protocol | TCP/UDP |
| Category | Authentication |
| Default encryption | No |
Security note. Port 88 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 88 used for?
Port 88 is Kerberos, the ticket-based authentication protocol behind Active Directory logins. Clients contact the Key Distribution Center here to obtain and present tickets.
Is port 88 TCP or UDP?
Port 88 (Kerberos) uses TCP/UDP.
Is port 88 secure?
Port 88 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 88 on my firewall?
Only if you specifically need Kerberos. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.