371
Summary
- // typical exposure
- Internal-only — IBM Rational ClearCase's albd service brokers internal SCM client/server connections (VOBs, views, license servers) with no documented legitimate public-facing use, so it should be restricted to trusted corporate networks rather than exposed to the internet.
- // common applications
- IBM Rational ClearCaseAtria ClearCase Traffic on this port is most often the albd broker for IBM Rational ClearCase (formerly Atria/Rational ClearCase) SCM client/server communications; no other community-sourced software sightings on this port were found in this research pass.
- // analyst note
- A responsive 371/tcp indicates an IBM Rational/Atria ClearCase albd service; treat internet-facing instances as anomalous and verify authorized enterprise use before assuming compromise.
- // if you see it open
- Enterprise SCM traffic intended for trusted internal/corporate networks only; no documented legitimate public-facing use. Unexpected public exposure is atypical and should be treated as a likely misconfiguration or investigated for anomalous activity. No CVE or dated scanning/exposure telemetry (e.g., Shodan/Censys) was verified in this pass.
About port 371/tcp.
Port 371/tcp carries albd, the Atria/ClearCase Location Broker Daemon used by IBM Rational ClearCase (formerly Atria/Rational ClearCase); it should stay internal-only rather than be exposed to the public internet.
IANA registers 371 as clearcase for both TCP and UDP, assignee Dave LeBlang, with a blank Reference column — no RFC or specification is cited; the assignee and contact columns separately carry Dave LeBlang, typical of early-era IANA registrations that predate the RFC-citation convention.
albd brokers client/server connections for ClearCase's version-control and software-configuration-management components — VOBs (versioned object bases), views, and license servers — in networked or multi-site ClearCase deployments. No RFC formally documents the protocol; the assignment is a vendor registration rather than a standards-track specification.
Research in this pass found no additional community-sourced software sightings on port 371 beyond ClearCase itself, and no dated scanning/exposure telemetry (e.g., Shodan or Censys figures) was retrievable, so exposure prevalence is Unknown rather than assumed.
- IANA assignment
clearcase— "Clearcase"; Reference column blank — no RFC or specification cited; assignee and contact columns separately carry Dave LeBlang; dual-registered 371/tcp + 371/udp [Confirmed] — IANA Service Name and Transport Protocol Port Number Registry- Range class
- well-known (0–1023) [Confirmed] — IANA registry
- Prevalence
- no nmap-services or scanning frequency figure was retrieved in this research pass [Unknown]
- Related ports
- 371/udp (same dual IANA registration); no other closely related ports identified in this pass
Primary use
Atria/ClearCase Location Broker Daemon (albd) — RPC connection brokering for IBM Rational ClearCase (formerly Atria/Rational ClearCase) software configuration management / version control
Other/unofficial uses
none identified beyond ClearCase in this pass [Unknown]
Security implications
enterprise SCM traffic intended for internal/trusted networks only; unexpected internet-facing exposure is atypical and likely a misconfiguration; no CVE or scanning telemetry was verified in this pass
Typically seen on
corporate/enterprise networks running IBM Rational ClearCase (VOB servers, view servers, license servers) in networked or multi-site deployments
- Analyst note
- A responsive 371/tcp indicates an IBM Rational/Atria ClearCase albd service; treat internet-facing instances as anomalous and verify authorized enterprise use before assuming compromise.
About port 371/udp.
Port 371/udp carries the IANA-registered clearcase service, and it should stay internal-only rather than face the public internet. IANA lists it (alongside the matching 371/tcp entry) for "Clearcase," assigned to Dave LeBlang, with no RFC reference cited.
The service is associated with IBM Rational ClearCase (originally Atria Software's product), a software configuration management and version-control system used in enterprise development shops. A secondary source labels the TCP counterpart "ClearCase albd," referring to ClearCase's Atria Location Broker Daemon — the RPC-style broker ClearCase clients use to locate ClearCase servers on a network; that "albd" detail is a community label layered on the IANA registration, not IANA-published text itself.
No RFC formally defines the protocol, and the IANA Reference column is blank for this entry. No registration or modification dates are listed either — both fields are blank in the source registry, not omissions on our part.
Research found no documented CVEs, malware associations, or active-scanning/exposure reports specific to port 371. That absence is reported honestly as Unknown rather than treated as a clean bill of health, since a niche enterprise SCM broker port receives little public security-research attention either way.
- IANA assignment
clearcase— "Clearcase"; reference (blank — no RFC cited in IANA registry); assignee [Dave_LeBlang]; dual-registered 371/tcp + 371/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry–736- Range class
- well-known (0–1023) [Confirmed] — port number 371 falls below 1024
- Prevalence
- Unknown — no nmap-services open-frequency figure was located for this port in this research pass [Unknown]
- Related ports
- 371/tcp (the same
clearcaseservice on the TCP counterpart) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry–736
Primary use
registered for IBM Rational/Atria ClearCase software configuration management (SCM) / version-control system client-server communication
Other/unofficial uses
TCP counterpart informally labeled "ClearCase albd" (Atria Location Broker Daemon, used for ClearCase client/server discovery) in a secondary source
Security implications
no documented CVEs, malware associations, or scanning-campaign reports were found for port 371; absence is reported as Unknown, not confirmed-safe [Unknown]
Typically seen on
enterprise development environments running IBM Rational/Atria ClearCase
- Analyst note
- a responsive port 371 outside a known ClearCase deployment is unusual and worth investigating as an exposed enterprise SCM broker rather than routine traffic.
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| clearcase | UDP | — | 0.06% |
| clearcase | TCP | — | 0.00% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.