4321

IANA registers TCP port 4321 as rwhois (“Remote Who Is”), referencing RFC 2167. That registration identifies the assigned service; it does not show that a particular host runs RWhois or establish that the port should be reachable from the public internet. With no deployment or audience evidence, the recommended exposure category is Unknown.

RFC 2167 describes RWhois as a client/server directory protocol for discovering, retrieving, and maintaining directory information. It organizes data hierarchically and can refer a client toward other servers as queries move closer to the authority for requested information. The RFC also describes operations that can modify server data, with guardian-based authentication and privacy controls.

These protocol capabilities make access control and authentication relevant when RWhois is deployed. The supplied evidence does not establish which implementations are in use, how common they are, or whether any specific network currently exposes this port. RFC 2167 is informational and does not define an Internet standard.

Registered service

IANA lists rwhois (“Remote Who Is”) for TCP port 4321, referencing RFC 2167.

Exposure

Unknown; the evidence identifies a protocol but does not establish its intended audience or any host's exposure.

Security

RFC 2167 describes directory operations including modification, and guardian-based authentication and privacy controls.

Protocol purpose

RWhois provides distributed discovery, retrieval, and maintenance of directory information

Port assignment

IANA lists rwhois for TCP port 4321 [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

Internet-standard status

RFC 2167 states that it does not specify an Internet standard [Confirmed] — https://www.rfc-editor.org/rfc/rfc2167.txt

Deployment on any particular host

Unknown [Unknown] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

IANA registers UDP port 4321 as rwhois, “Remote Who Is,” and references RFC 2167. That identifies the service associated with the port, but the supplied sources do not establish whether any system deploys RWhois over UDP or whether the service is intended for public access. Treat the public exposure policy as Unknown from this evidence.

RFC 2167 describes RWhois as a distributed directory protocol for discovering, retrieving, and maintaining information, including network objects such as domain names and IP networks. Servers organize data into authority areas. A query can receive data, an error, or a referral: a link referral points down to a more specific authority area, while a punt referral points upward to a parent area.

The RFC also describes security controls: guardian requirements can require clients to satisfy an authentication or encryption scheme to modify, delete, or possibly view guarded data. Objects and individual attributes marked private restrict public viewing. These are protocol provisions, not evidence that a UDP service is deployed or configured with those controls. RFC 2167 is informational and does not specify an Internet standard.

Service

IANA registers rwhois (“Remote Who Is”) for UDP port 4321 and cites RFC 2167.

Protocol

RWhois describes distributed directory lookup and maintenance, with authority areas and referrals that route queries upward or downward in a hierarchy.

Exposure

Unknown. The supplied evidence gives no intended audience or observed deployment for UDP/4321.

Security

RFC 2167 describes guardian authentication or encryption requirements and private objects or attributes; actual UDP configuration is unverified.

IANA service name

rwhois (“Remote Who Is”) [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

Protocol purpose

Distributed directory discovery, retrieval, and maintenance

RFC reference

RFC 2167, Informational [Confirmed] — https://www.rfc-editor.org/rfc/rfc2167.txt

Query routing

Authority areas use referrals; punt referrals point upward and link referrals downward [Confirmed] — https://www.rfc-editor.org/rfc/rfc2167.txt

Security provisions

Guardians can impose authentication or encryption requirements; private objects or attributes restrict viewing [Confirmed] — https://www.rfc-editor.org/rfc/rfc2167.txt

Deployment and public access intent for UDP/4321

Unknown [Unknown] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv