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Port 102ISO-TSAP Class 0

ISO Transport Service Access Point (TSAP) on TCP port 102 is primarily used in OSI protocols, notably for communication between industrial control systems and automation devices such as PLCs and SCADA systems. It facilitates the transport layer's connection-oriented communication, serving as a gateway to multiple higher-level protocols and services conforming to ISO standards..

inNetwork ServicesSystem
transport
tcp

single transport

in transit
cleartext

payload readable on path

assignment
official

registered with iana

risk
4/10

caution

lookups
12,044

rank 326 of 993 · top 33%

Technical Details

what runs on :102

Port 102 is assigned to ISO-TSAP (Transport Service Access Point) Class 0, which represents the standard interface point for connection-oriented transport in the OSI (Open Systems Interconnection) model. Specifically, TSAP enables Session Layer services by offering reliable transport provided by ISO Transport Protocol Class 0 over TCP. Though OSI protocols have largely been supplanted by TCP/IP standards, port 102 remains essential where OSI stacks persist — notably in secure, real-time communication environments.

One of the primary contemporary use cases for port 102 is facilitating communication via protocols such as Siemens' S7 (used for PLCs) and other industrial automation protocols. These protocols often leverage port 102 to manage command and data transfer sessions between programming devices, control servers, engineering workstations, and embedded controllers. The connection-oriented nature of Class 0 services ensures reliable data delivery which is critical in industrial control system (ICS) environments.

Despite declining general use of OSI protocols, port 102 has a niche but vital role within certain verticals, especially where long-lived, legacy OT (Operational Technology) systems are deployed. SCADA and Distributed Control Systems (DCS) often maintain compatibility with ISO-TSAP to ensure interoperability, deterministic behavior, and robust communication in tightly controlled industrial networks.

Security Information

exposure of :102

risk score

4/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

network services averages 3.9 across 604 ports — this one sits 0.1 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp

every listening transport is another surface to filter at the edge

security overview

Common vulnerabilities associated with port 102 center around:

  • Exposure of industrial control devices and systems to unauthorized access, especially if port 102 is unfiltered externally
  • Susceptibility to protocol misuse or exploitation, as authentication and encryption are often absent in native implementations
  • Potential for exploitation through replay attacks, man-in-the-middle (MITM) attacks, or session hijacking if protective measures are lacking
  • Increased attack surface due to legacy protocol stack vulnerabilities or unpatched systems

Mitigation strategies include:

  • Strict network segmentation isolating ICS and OT environments from IT networks and external access
  • Applying access control lists (ACLs) on firewalls and routers to tightly restrict communication on port 102
  • Deploying industrial-aware intrusion detection/prevention systems (IDS/IPS) capable of identifying anomalous behavior
  • Implementing VPNs and application-layer encryption to secure data transit, where feasible
  • Ensuring industrial devices are patched regularly, and unused services disabled to reduce the attack surface
  • Applying robust authentication mechanisms and role-based access controls

Proper security hygiene and dedicated ICS security strategies are essential to protect devices using ISO-TSAP on port 102 from exploitation.

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all 604 in network services →

the 8 most looked-up other ports in network services — 604 ports carry that label.

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risk mix of the 8 listed

  • caution100%

0 of 8 encrypted