Port 66Oracle SQL*Net

Historic IANA assignment for Oracle SQL*Net traffic on TCP and UDP port 66.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 8/10
lookups: 0

also known as Oracle Net, TNS

Technical Details

what runs on :66

Oracle SQL*Net is Oracle's TNS-based client/server database protocol. A client contacts an Oracle listener, negotiates or receives a database service endpoint, and then carries Oracle session traffic over the connection; traffic is not inherently encrypted. The IANA assignment covers TCP and UDP 66, but it is historic and modern Oracle listeners default to TCP 1521, so a service on 66 would generally be a deliberately configured legacy or non-default listener.

Security Information

exposure of :66

risk score

8/ 10risk

treat as sensitive. widely scanned and regularly exploited when reachable — restrict it to known sources.

databases averages 3.7 across 143 ports — this one sits 4.3 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp · udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

An exposed Oracle listener can disclose database services and provide a path to database authentication and access, while cleartext or weakly configured SQL*Net can expose credentials and data. It should not be reachable from the public internet; restrict it with firewall rules, use Oracle Native Network Encryption or TLS where supported, and maintain strong database authentication and patching.

Record

iana registry entry

port: :66
service: Oracle SQL*Net
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 8/10risk
category: Databases
usage: SQL*Net, now generally called Oracle Net Services, carries client connections to Oracle Database listeners and database sessions. Port 66 is a historical IANA assignment and is rarely encountered; current Oracle installations normally listen on TCP 1521 or a site-specific port.
lookups: 0rank 993
added: 2026-09-16
updated: 2026-09-22
references: IANA service name registry — port 66

Something wrong?

This record is maintained by the engineers who use port 66. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-22.

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edit this record →back to the registry

Related Ports

all 143 in databases →

the 8 most looked-up other ports in databases — 143 ports carry that label.

port	service	proto	category	risk	views
:8882	Atlasz Secure App Server	TCP	Web Services	caution	66.9k
:9001	ETL Service Manager	TCPUDP	Databases	caution	28.6k
:2484	Oracle SSL Listener	TCPUDPtls	Security	caution	25.0k
:5495	Applix TM1 Admin	TCP	Databases	caution	24.8k
:591	FileMaker Web Sharing	TCP	Web Services	caution	23.1k
:1521	Oracle TNS Listener	TCP	Security	caution	19.6k
:21001	AMLFilter Admin	TCP	Security	caution	19.2k
:18206	Audition FAM DB	TCPUDP	Databases	caution	19.1k

risk mix of the 8 listed

caution100%

1 of 8 encrypted

Port :66Oracle SQL*Net

Technical Details

Security Information

Related Ports

Port 66Oracle SQL*Net