549

Port 549/tcp carries no documented protocol beyond a bare IANA registration, and no sourced evidence supports treating it as belonging on the public internet — there is no curated basis to call it either internet-facing or a known backdoor, so it should be treated as unknown-use and investigated rather than assumed safe if seen open.

IANA registers 549/tcp (dual-registered with 549/udp) under the service name idfp, with the description field literally reading "IDFP" and the Reference field blank. No RFC, vendor specification, or independent technical write-up describing an idfp protocol turned up in this research pass — the registry entry itself is the only documentation located.

No CVE referencing port 549 is recorded in the NVD as of an August 2026 search, and auditmypc.com's port-549 page carries no trojan or virus verdict for it. Generic port-lookup mirrors (SpeedGuide, adminsub.net, my-addr.com) only restate the bare IANA registration with no application names attached, and no forum or vendor-support thread describing real-world traffic on this port was found.

The measured nmap-services open-frequency for 549/tcp is exactly 0 — a sampled, not-observed-open reading, not an absence of data — while 549/udp shows a small nonzero frequency of about 0.000461. Given the combination of an undocumented protocol and no observed open instances, an analyst encountering this port open should treat it as an anomaly worth investigating rather than a recognized service.

Exposure

No documented legitimate deployment or protocol specification for idfp/549 was found; treat unexpected traffic on this port as worth investigating rather than assuming a known application.

Prevalence

nmap-services open-frequency for 549/tcp is 0 (sampled, not observed open); 549/udp is approximately 0.000461.

Recommendation

Absent any documented purpose, an open port 549/tcp warrants investigation as an unknown or anomalous service rather than routine acceptance.

IANA assignment

idfp — description "IDFP"; reference (blank — no RFC cited in IANA registry); assignee [Ramana_Kovi]; dual-registered 549/tcp + 549/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/tcp

Range class

well-known (0–1023) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/tcp

Prevalence

nmap-services open-frequency 549/tcp = 0 (sampled, not observed open); 549/udp ≈ 0.000461 [Confirmed] — this site's own tooling

Related ports

549/udp (dual idfp registration) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/udp

Primary use

registered name idfp only; no RFC or independent protocol documentation found describing its function

Other/unofficial uses

none found in this research pass [Unknown]

Security implications

no CVE recorded in the NVD as of an August 2026 search; no malware/trojan verdict on auditmypc.com's port-549 page

Typically seen on

Unknown — no documented deployments or community sightings surfaced [Unknown]

Analyst note

An open port 549/tcp has no established legitimate use documented anywhere found; treat as an anomaly to investigate rather than a recognized service.

Port 549/udp carries a service IANA lists only as idfp, and no publicly available specification, vendor implementation, or usage report was found for it — so whether an open 549/udp reflects legitimate use is unknown; the evidence base supports neither a benign nor a hostile classification.

IANA's Service Names and Port Numbers registry assigns 549/udp (and the paired 549/tcp) to idfp, with the description field reading only "IDFP" and no expanding text. The assignee on record is [Ramana_Kovi], and the Reference column is blank — no RFC or other specification is cited for this registration.

What "IDFP" stands for or how the protocol actually behaves is not documented anywhere located in this research. No vendor page, blog post, or forum/support thread was found describing an application, appliance, or game that generates traffic on this port, so no specific software can be named as a likely source.

No CVE is recorded against this port or service as of an August 2026 search, and no malware or trojan association could be confirmed. GRC's Port Authority page for 549 lists only the bare name and purpose with no further detail, and a fetch of the auditmypc.com page for port 549 did not return content that could be confirmed as containing an actual verdict line, so no positive or negative malware claim is drawn from it.

Measured open-frequency for this port is very low: the repo's nmap-services-derived data records 549/udp at roughly 0.046% and 549/tcp at exactly 0 (a genuine sampled reading of no observed open hosts, not a missing measurement). Both figures are consistent with a rarely-deployed, sparsely documented service.

Exposure

Unknown — no specification, vendor sighting, CVE, or telemetry was found either confirming or ruling out legitimate use of an internet-facing 549/udp.

Protocol documentation

IDFP has no publicly located specification beyond the bare IANA registry entry, so its actual function and attack surface are Unknown.

Malware association

Unconfirmed — no source (including GRC's Port Authority and auditmypc.com) yielded a verifiable positive or negative malware verdict for this port.

Prevalence

nmap-services open-frequency ~0.046% for 549/udp and 0 for 549/tcp (sampled, not observed open) — consistent with a rarely-seen service.

IANA assignment

idfp — description literally "IDFP"; Reference column blank; assignee [Ramana_Kovi]; dual-registered 549/tcp + 549/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/udp

Range class

well-known (0–1023) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/udp

Prevalence

nmap-services open-frequency 549/udp ≈ 0.000461 (~0.046%); 549/tcp = 0 (sampled, not observed open) [Confirmed] — this site's own tooling

Related ports

549/tcp (same idfp dual registration) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry idfp 549/tcp

Primary use

Unknown — no protocol specification or expanded description found beyond the bare IANA registration

Other/unofficial uses

none found — no vendor documentation, blog, or forum thread reports an application using this port [Unknown]

Security implications

no CVE recorded as of an August 2026 search; no confirmed malware association (auditmypc.com verdict could not be confirmed via fetch, GRC Port Authority entry is a bare stub)

Typically seen on

Unknown — no application or platform sightings surfaced in research [Unknown]

Analyst note

Given the near-total absence of protocol documentation and vendor adoption, whether an open 549/udp reflects legitimate use is unknown — the evidence base neither confirms nor rules out legitimate use.