831

Port 831 is, as of the live IANA registry (Last Updated 2026-05-29), Reserved with a blank service name on both the TCP and UDP rows, a modification date of 2025-09-29, and an assignment note stating it was previously assigned to NETCONF over BEEP but released by [RFC9900]; the service name netconf-beep survives only as a name-only registry entry (no port number) with the description "NETCONF over BEEP" and references [RFC4744][RFC9900]. The port previously carried NETCONF over BEEP (the Blocks Extensible Exchange Protocol), defined in RFC 4744 (December 2006, Lear and Crozier, Cisco) as one of the alternative NETCONF transport mappings. That transport never achieved meaningful adoption — SSH (on port 830) won decisively — and RFC 4744 was moved to Historic status; the process began with B. Wijnen's 2012 draft noting the document had shown very little if any implementation or deployment and that no one in the NETCONF working group was interested in working on it anymore. RFC 9900 (December 2025, M. Boucadair, Orange) then de-assigned the port number, stating that it releases IANA-assigned NETCONF-related port numbers that have not been in use in production networks and that there are no known implementations and deployments relying on them; per RFC 6335 section 8.2, only the port number was de-assigned while the service name was retained as a name-only entry. The current registry status is therefore Reserved, with no live reference on the port row. Security-wise there is effectively nothing to defend — the port is not associated with any current standardized service. For an analyst, an open 831 today is rare, legacy, and anomalous; nmap-services lists 831/tcp at roughly 0.000050, and any traffic should be treated as non-standard.

IANA assignment

831/tcp + 831/udp — Reserved (service name blank; modification date 2025-09-29; "Previously assigned to NETCONF over BEEP but released by [RFC9900]"); the name-only entry netconf-beep ("NETCONF over BEEP") survives with [RFC4744][RFC9900]

[IANA-assigned, verified live] — IANA Service Name and Transport Protocol Port Number Registry

Range class

well-known (0–1023)

Prevalence

negligible; nmap-services 831/tcp ~0.000050 (de-facto) [Well-established] — nmap-services file

Related ports

830 (netconf-ssh — the transport that won)

Primary use

formerly NETCONF over BEEP (RFC 4744); now de-assigned/Reserved

Other/unofficial uses

none [Well-established]

Security implications

not associated with any current standardized service; an open 831 is anomalous/legacy [Well-established]

Typically seen on

nothing current (historical NETCONF-over-BEEP only)

Analyst note

An open 831 today is rare/legacy and anomalous (port de-assigned by RFC 9900, Dec 2025); treat any traffic as non-standard.