Should port 66 be open on my firewall?

Port 66 is generally safe to have open. Apply standard security practices: keep software updated and monitor access logs.

What transport protocol does port 66 use?

Port 66 (Oracle SQL*NET) uses the TCP/UDP transport protocol and falls under the Database category.

:66 (TCP/UDP)

Oracle SQL*NET

Q: Is port 66 (Oracle SQL*NET) dangerous?

Port 66 is classified as low risk. This service uses encryption or has a minimal attack surface, making it relatively safe to expose with standard security practices.

Low Risk

TCP/UDP — Database

Port Overview

Port Number 66

Service Name Oracle SQL*NET

Transport Protocol TCP/UDP

Category Database

Security Risk Low

Port Range Well-Known (0-1023)

What is Port 66?

Port 66 was historically associated with Oracle SQL*NET, an early version of Oracle's proprietary network protocol for database communication before it migrated to port 1521. This port is largely unused today as Oracle Net Services standardized on higher port numbers.

TCP/UDP Database

Security Considerations

Port 66 (Oracle SQL*NET) is classified as low risk. This service uses encryption or has a minimal attack surface, making it relatively safe to expose.

Recommendation: Standard security practices apply. Keep software updated and monitor access.

Related Ports — Database

118 SQL Services 134 INGRES-NET 142 BL-IDM 150 SQL-NET 156 SQL Service 181 Unify 188 MUMPS 210 ANSI Z39.50

Related Terms

ASN BGP Hijack Data Center Domain Name Dual Stack Internet Exchange Point (IXP)