557
Summary
- // if you see it open
- No CVE, vulnerability advisory, or malware/trojan association is recorded for 557/tcp as of a September 2026 search; AuditMyPC's port-557 page (whose template negative-verdict framing should not be read as an accusation) lists no virus/trojan association. As an OpenVMS system inter-process communication facility rather than a networked application protocol, an open 557/tcp on a non-OpenVMS host is unexpected and worth investigating; on OpenVMS/VSI systems it should be limited to trusted or cluster-internal networks rather than exposed to the public internet.
- // analyst note
- Treat an open 557/tcp outside an OpenVMS/VSI environment as anomalous and worth investigating; on OpenVMS systems, keep it confined to trusted or cluster-internal networks. [Likely]
About port 557/tcp.
Port 557/tcp carries openvms-sysipc, an OpenVMS system inter-process communication (SYSIPC/ICC) facility; it belongs on trusted internal or cluster networks rather than exposed to the public internet.
IANA registers 557/tcp and 557/udp under the same service name, openvms-sysipc, with assignee [Alan_Potter] and a blank reference field — no RFC documents the protocol. The registry entry carries no description beyond the bare name.
VSI/HPE OpenVMS documentation discusses SYSIPC/ICC (Inter-Computer Communication) primitives in general terms, but no dedicated wire-protocol specification for this port was found. General port-reference sites (SpeedGuide, AuditMyPC, GRC Port Authority) all echo only the bare IANA assignment, with no third-party software reported using this port.
Measured against the nmap-services frequency data's nmap-services-derived open-frequency figures, 557/tcp shows 0.000113 (about 0.011% of scanned hosts) and 557/udp shows 0.000461 — both rare-to-negligible observed-open rates, consistent with a niche OS-internal facility rather than a widely deployed network service.
No CVE, vulnerability advisory, or malware/trojan association is recorded for this port as of a September 2026 search. Because it is an inter-process communication facility rather than a networked application protocol, an open 557/tcp outside an OpenVMS/VSI environment is unexpected and worth investigating rather than treated as routine.
- Exposure
- Internal-only — openvms-sysipc is an OS-level inter-process communication facility, not a protocol meant for public-internet reach.
- Prevalence
- Rare; the nmap-services frequency data (nmap-services derived) records 557/tcp at open-frequency 0.000113 and 557/udp at 0.000461.
- CVE / malware
- None recorded as of a September 2026 search; AuditMyPC lists no virus/trojan association for this port (its template negative-verdict framing is not an accusation).
- Anomaly signal
- An open 557/tcp on a non-OpenVMS host has no known legitimate explanation and should be treated as worth investigating.
- IANA assignment
openvms-sysipc— description "openvms-sysipc"; reference blank; assignee [Alan_Potter]; dual-registered 557/tcp + 557/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/tcp- Range class
- well-known (0–1023) [Confirmed]
- Prevalence
- the nmap-services frequency data (nmap-services derived) open-frequency 557/tcp = 0.000113 (~0.011%), 557/udp = 0.000461 (~0.046%) [Confirmed] — this site's own tooling
- Related ports
- 557/udp (same openvms-sysipc registration, dual-registered) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp
Primary use
OpenVMS system inter-process communication (SYSIPC/ICC) facility per the IANA assignment; no RFC documents the protocol
Other/unofficial uses
none found in community sources beyond the OpenVMS SYSIPC facility itself [Unknown]
Security implications
no CVE or malware/trojan association recorded as of a September 2026 search
Typically seen on
OpenVMS / VSI OpenVMS systems running the TCP/IP Services stack
- Analyst note
- Treat an open 557/tcp outside an OpenVMS/VSI environment as anomalous and worth investigating; on OpenVMS systems, keep it confined to trusted or cluster-internal networks. [Likely]
About port 557/udp.
Port 557/udp carries openvms-sysipc, IANA's registration for OpenVMS system inter-process communication (IPC); it should stay internal to an OpenVMS cluster rather than be exposed to the public internet.
The IANA Service Name and Port Number Registry lists openvms-sysipc as registered on both 557/tcp and 557/udp under the same name, with the assignee recorded as Alan Potter and no RFC or other reference cited. The registry's description field simply repeats the service name, leaving no fuller protocol specification publicly available.
No vendor documentation, forum post, or blog entry describing real-world software using 557/udp turned up in this search, and no community-sourced sighting could be confirmed. In the nmap-services-derived corpus, the port shows a measured open-frequency of 0.000461 for UDP (0.000113 for the paired TCP registration) — rare but not absent, consistent with an obscure, legacy-era assignment that still occasionally appears in scans.
No CVE or malware association is recorded against this port as of a September 2026 search, and no honeypot or exposure study specific to 557/udp was found. The combination of a narrow legacy purpose, no public protocol spec, and low but non-zero scan sightings points to a service that has little reason to be reachable from outside its own cluster.
- Exposure
- Internal-only — openvms-sysipc is a system-level IPC mechanism intended for use within an OpenVMS cluster, not for public internet exposure.
- Malware/Trojan Association
- Not listed; auditmypc.com records an explicit "No" verdict for virus/trojan association on port 557, and no independent trojan-port list names it as malware-associated as of a September 2026 search.
- Documentation Gap
- No RFC or protocol specification is published beyond the bare registry entry, so the specifics of the wire protocol carried on 557/udp are Unknown.
- Scanning Exposure
- No dedicated honeypot or scan-prevalence study specific to 557/udp was found; its measured open-frequency in the nmap-services corpus is low (0.000461 for UDP) rather than zero.
- IANA Service Name
- openvms-sysipc [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp)
- IANA Reference/RFC
- None listed in the registry [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp)
- Dual Registration
- Also registered on 557/tcp under the same service name [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/tcp and 557/udp)
- Prevalence
- Measured open-frequency 0.000461 for 557/udp (0.000113 for 557/tcp) in the nmap-services-derived corpus [Confirmed] (this site's own tooling)
Primary Use
OpenVMS system inter-process communication (IPC); no published protocol specification found beyond the registry entry [Likely] (https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=557)
Malware/Trojan Association
Not listed as malware/trojan-associated [Likely] (https://www.auditmypc.com/tcp-port-557.asp)
- Port
- 557 [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp)
- Transport
- udp [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp)
- Assignee
- Alan Potter, per the registry contact field [Confirmed] (the IANA Service Name and Transport Protocol Port Number Registry openvms-sysipc 557/udp)
- Common Applications/Sightings
- None found; no vendor docs, forum threads, or blog posts describing real-world use of this port turned up in this search [Unknown]
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| openvms-sysipc | UDP | — | 0.05% |
| openvms-sysipc | TCP | — | 0.01% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.