155
Summary
- // if you see it open
- No known CVE or malware family targets this port. Sub-1024 range requires privileged bind, so an unexpected listener would be notable. Not commonly scanned or exploited.
- // analyst note
- An open port 155 is statistically rare and has no documented legitimate modern use — treat a live listener as an anomaly worth investigating rather than a routine service.
About port 155/tcp.
Port 155/tcp is registered with IANA as netsc-dev, described simply as "NETSC," with assignee and contact both listed as Sergio Heker. The registration is dual — identical service name, description, assignee, and contact appear on both the tcp and udp rows — and every other column in the IANA registry (Registration Date, Modification Date, Reference, Service Code, Unauthorized Use Reported, Assignment Notes) is blank, so no RFC, date, or usage note can be honestly attached to it. A secondary aggregator (connected.app) claims the netsc-dev/netsc-prod name pair traces back to the "Assigned Numbers" RFCs of the early 1990s (RFC 1340, July 1992, and RFC 1700, October 1994), but that provenance does not appear in IANA's own live Reference field, so it is carried here only as an unconfirmed, single-source claim rather than a verified citation. No surviving specification documents what protocol actually ran on the port, and no mainstream client, server, or library is known to use it today. The registrant's name is associated in the historical record with JvNCnet, an early regional network operator, which is a plausible but unproven origin for a "dev" service on this port. Scan-frequency data suggests the port is essentially never found open in modern exposure surveys, and no CVE or malware family is tied to it, so an unexpected listener here would be unusual and worth investigating rather than dismissing as routine.
- IANA assignment
netsc-dev— "NETSC"; reference blank; assignee/contact Sergio Heker; dual-registered 155/tcp + 155/udp [Confirmed] — IANA Service Name and Transport Protocol Port Number Registry (https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=155)- Range class
- well-known (0–1023)
- Prevalence
- reported by a secondary aggregator as essentially never seen open in scan data (TCP frequency ~0, UDP slightly higher but still very rare); the underlying raw nmap-services frequency file was not independently re-verified this pass [Likely] — https://www.connected.app/bg/ports/155
- Related ports
- no adjacent or paired port number is confirmed in the registry data gathered this pass
Primary use
Unknown — no surviving RFC or vendor spec documents the actual protocol run on this port; "dev" naming suggests a development/internal counterpart to an implied "netsc-prod" service, but no such pairing is confirmed in the registry itself [Unknown]
Other/unofficial uses
none independently documented; no known mainstream software, daemon, or protocol implementation binds to this port today [Unknown]
Security implications
no known CVE or malware family targets this port; being in the well-known (sub-1024) range, binding it requires elevated privileges, so an unexpected listener would be notable
Typically seen on
unknown; the registrant's historical association with JvNCnet (an early regional supercomputer network) is a plausible but unproven link to the port's original purpose [Unknown]
- Historical RFC association (unconfirmed)
- a secondary source states netsc-dev/netsc-prod appeared in the "Assigned Numbers" documents RFC 1340 (July 1992) and RFC 1700 (October 1994); not present in IANA's own live Reference field for this entry, so treated as unverified provenance, not a citable IANA reference[Likely, single-source] — https://www.connected.app/bg/ports/155
- Analyst note
- An open port 155 is statistically rare and has no documented legitimate modern use — treat a live listener as an anomaly worth investigating rather than a routine service.
About port 155/udp.
Port 155/udp is registered with IANA as netsc-dev with the description "NETSC," assignee and contact [Sergio_Heker], and blank Registration Date, Modification Date, and Reference columns — dual-registered with an identical entry at 155/tcp. Sergio Heker was the founder and operator of JvNCnet (the John von Neumann National Supercomputer Center network), one of the original NSFNET regional networks; the port's naming pattern strongly suggests a paired production/development registration alongside port 154 (netsc-prod) for an internal NETSC network-management tool from that era, though IANA records no assignee for the port-154 rows, so any shared-owner inference is unverified. No RFC or public protocol specification for NETSC was ever published, and no evidence surfaced of any currently maintained software implementing netsc-dev as a live listening service — this reads as a dormant, legacy IANA registration rather than an actively used protocol. No authoritative CVE or malware association was confirmed; a single non-authoritative community reference site reports no known virus/trojan tie to UDP 155, but that source is not IANA/CVE-grade and is cited only as a weak corroborating signal, not a finding. A vendor application-signature page nominally citing port 155 was excluded as internally inconsistent (it lists an unrelated port set). Because the registration predates modern documentation norms and no protocol details or operational sightings could be verified, most operational fields here are honestly Unknown rather than fabricated.
- IANA assignment
netsc-dev— "NETSC"; reference (blank — no RFC cited in IANA registry); assignee/contact[Sergio_Heker]; dual-registered 155/udp + 155/tcp with identical fields [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry, https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=155- Range class
- well-known (0–1023) [Confirmed]
- Prevalence
- nmap-services observed open-frequency 155/udp ≈ 0.000659 — very low (roughly 7 in 10,000 scanned hosts in the nmap-services sample); the paired 155/tcp row carries a frequency of 0 (never observed open in the same sample) [Confirmed] — nmap-services dataset. Read that figure with the standard caveat that general UDP scans are slower and harder to cover than TCP scans per Nmap documentation (not port-155-specific)[Likely] — https://nmap.org/book/scan-methods-udp-scan.html
- Related ports
- 154/tcp and 154/udp (
netsc-prod) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry-386
Primary use
historical NETSC network-management tool tied to Sergio Heker / JvNCnet (early NSFNET regional network); paired with the "prod" counterpart at port 154
Protocol specification
no RFC or public protocol document was ever published for NETSC
Other/unofficial uses
no evidence of any currently maintained software implementing netsc-dev; appears to be a dormant legacy registration
Security implications
no known CVEs found in this pass (absence not exhaustively confirmed); a single non-authoritative community site reports no known virus/trojan association for UDP 155, low-confidence and excluded as a finding rather than treated as proof
- Data-quality note
- a Juniper Threat Labs "NETSC-DEV" signature page nominally cites port 155 TCP/UDP but lists an inconsistent, unrelated port set alongside it; excluded as unreliable rather than cited as a finding [Unknown] — https://www.juniper.net/us/en/threatlabs/application-signatures/detail.NETSC-DEV.html
- Analyst note
- legacy dormant registration with no modern operational footprint verified; treat an open 155/udp as unusual and worth investigation rather than an expected service.
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| netsc-dev | UDP | — | 0.07% |
| netsc-dev | TCP | NETSC | 0.00% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.