1985

IANA registers 1985/tcp as hsrp (Hot Standby Router Protocol), but the supplied HSRP specification describes operation over UDP port 1985. The evidence does not establish what, if anything, runs on TCP port 1985 in a particular network, or whether it should be publicly reachable. Treat a TCP service there as unidentified until its application is verified.

RFC 2281 describes HSRP as a first-hop redundancy protocol for routers on multi-access, multicast- or broadcast-capable LANs. Participating routers present hosts with a virtual router; a standby router can take over packet forwarding if the active router fails. The RFC specifies HSRP messages over UDP, sent to multicast address 224.0.0.2 with TTL 1. This is evidence about UDP, not TCP.

Because the documented protocol serves routers and hosts on a LAN and the TCP assignment alone does not establish a TCP audience, the appropriate public access policy for 1985/tcp is unknown. The RFC also discusses clear-text authentication data, a security consideration for HSRP deployments, but that detail does not identify or characterize TCP traffic.

Registered name

IANA lists hsrp for 1985/tcp, described as Hot Standby Router Protocol. [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

Protocol evidence

RFC 2281 specifies HSRP over UDP port 1985; it does not establish HSRP operation over TCP. [Confirmed] — https://www.rfc-editor.org/rfc/rfc2281.txt

Exposure

Unknown; the TCP assignment does not establish the intended audience or observed deployment. [Unknown] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

IANA service name

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

IANA description

Hot Standby Router Protocol [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

IANA reference

RFC 2281 [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

RFC transport and port

HSRP runs over UDP port 1985 [Confirmed] — https://www.rfc-editor.org/rfc/rfc2281.txt

TCP deployment

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