493

Port 493/tcp carries ticf-2, IANA's "Transport Independent Convergence for FNA" assignment; it is a legacy vendor-registered port with no evidence of legitimate public-internet use, so it should stay internal-only if it is running at all.

IANA's Service Names and Port Numbers registry lists 493/tcp and 493/udp identically as ticf-2, assignee Mamoru Ito, with a blank Reference field — meaning no RFC or other standards-track document was ever attached to the assignment. FNA (Fujitsu Network Architecture) is Fujitsu's legacy proprietary mainframe/host networking stack, and "ticf" most plausibly denotes a transport-independent convergence function that bridges FNA traffic onto TCP/IP, though IANA's own text does not spell this out further.

No credible vendor documentation, blog post, or forum thread was found in an August 2026 search naming specific software that generates traffic on this port. Generic port-lookup aggregators (SpeedGuide, AuditMyPC, SANS ISC, adminsub.net) simply restate the IANA registry line rather than documenting an observed application, and SANS ISC's live port-493 activity page showed no populated scan data at fetch time.

No CVE or malware family is documented against port 493 as of an August 2026 search. AuditMyPC's port-493 page carries the site's standard disclaimer sentence directly above its own "Virus/Trojan: No" verdict — read correctly, that is a negative finding, not evidence of any association.

IANA assignment

ticf-2 — "Transport Independent Convergence for FNA"; reference (blank — no RFC cited); assignee Mamoru Ito; dual-registered 493/tcp + 493/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry ticf-2 493/tcp

Range class

system/well-known (0–1023) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry ticf-2 493/tcp

Prevalence

nmap-services open-frequency 493/tcp = 0.000025 (~0.0025%); 493/udp = 0.00056 (~0.056%) [Confirmed] — this site's own tooling

Related ports

other system-range Fujitsu/legacy host-integration assignments in the low 400s–500s block; contrast the /port/ hub

Primary use

vendor-registered transport-convergence function for Fujitsu's FNA (Fujitsu Network Architecture) mainframe/host networking; no RFC attached

Other/unofficial uses

none documented

Security implications

no CVE or malware association documented as of August 2026; AuditMyPC boilerplate correctly read as a negative, not a finding; no notable scanning activity observed on SANS ISC

Typically seen on

legacy Fujitsu FNA-integrated host/mainframe environments, if anywhere; otherwise an anomaly

Analyst note

An open 493/tcp is rare and has no documented modern legitimate driver outside legacy Fujitsu FNA contexts — treat an unexpected hit as worth investigating rather than routine.

Port 493/udp carries ticf-2, IANA's registered name for "Transport Independent Convergence for FNA"; it is a legacy, no-RFC registration with no evidence of active modern deployment, so it should never appear as internet-facing traffic and a response on it is a signal worth investigating rather than a normal service.

IANA registered 493/udp (and the paired 493/tcp) to ticf-2 under assignee Mamoru Ito, with a blank Reference column — no citing RFC exists in the registry. "FNA" most plausibly points to Fujitsu Network Architecture, a mainframe/host networking architecture, and ticf-2 pairs with a companion service ticf-1 on port 492, consistent with a narrow vendor-specific transport-convergence pairing rather than a broadly deployed general-purpose protocol.

No authoritative technical specification beyond the bare IANA entry was found, and no vendor documentation, forum sighting, or malware report ties concrete software to this port as of an August 2026 search. nmap-services records an open-frequency of 0.00056 for 493/udp (0.000025 for 493/tcp), both near the low end of the measured range, consistent with a port that is essentially never seen open in practice.

IANA assignment

ticf-2 — "Transport Independent Convergence for FNA"; reference (blank — no RFC cited); assignee Mamoru Ito; dual-registered 493/tcp + 493/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry ticf-2 493/udp

Range class

well-known/system (0–1023) [Confirmed] — this site's own tooling

Prevalence

nmap-services open-frequency 493/udp ≈ 0.00056 (~0.056%); 493/tcp ≈ 0.000025 [Confirmed] — this site's own tooling

Related ports

492/tcp+udp (ticf-1, companion registration) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry ticf-1 492/udp

Primary use

Legacy vendor-oriented transport-convergence service; no RFC, no evidence of broad deployment

Other/unofficial uses

Possibly linked to Fujitsu Network Architecture (FNA) naming convention; pairs with ticf-1 on port 492

Security implications

essentially never legitimately open; no CVE or malware association found as of an August 2026 search

Typically seen on

not observed in normal deployments; an open instance is an anomaly [Unknown]

Analyst note

An open 493/udp is statistically rare and has no established legitimate modern use — treat as anomalous and investigate rather than assume normal service traffic.