991
Summary
- // if you see it open
- RFC 4707 is experimental and the supplied excerpt does not specify UDP message formats or behavior. The evidence does not establish endpoint identity, implementation, or safety.
- // common applications
- Netnews administration framework (regist Unknown; no traffic observations or deployment measurements were supplied.
About port 991/udp.
IANA assigns UDP port 991 the service name nas, described as Netnews Administration System, and references RFC 4707. The registration identifies the intended service, but the supplied evidence does not establish that NAS is deployed on this port or that traffic is present. Public internet exposure is therefore Unknown from this evidence.
RFC 4707 describes NAS as an experimental client-server framework for administering Netnews. Its distributed hierarchical database makes newsgroup and hierarchy information available to news servers, administrators, and news readers. The RFC says NAS communication is based on TCP and UDP, but the supplied excerpt gives protocol behavior in detail for TCP only; it does not establish UDP message formats or exchange behavior.
The RFC characterizes NAS as an experimental protocol and says it is not an Internet standard. No evidence here measures deployment or prevalence, identifies current operators, or establishes malware associations. Treat the service label as a registry description, not proof that a responding UDP endpoint implements NAS.
- Protocol
- IANA registers
nasfor Netnews Administration System on UDP port 991; actual deployment is Unknown. - Exposure
- Intended for news servers, administrators, and readers; RFC 4707 permits NAS servers to be located elsewhere on the Internet. Actual deployment and reachability on UDP port 991 are Unknown.
- Security
- RFC 4707 is experimental; the supplied excerpt does not describe UDP behavior in sufficient detail to assess its exchange semantics.
- Service name
- nas [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv
- Registered description
- Netnews Administration System [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv
- RFC characterization
- Experimental protocol; not an Internet standard [Confirmed] — https://www.rfc-editor.org/rfc/rfc4707.txt
- UDP deployment or traffic
- Unknown [Unknown] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| nas | TCP | Netnews Administration System | 0.00% |
| nas | UDP | Netnews Administration System | 0.00% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.