Port 55ISI Graphics Language
ISI Graphics Language (ISI-GL) is an early network protocol designed primarily for transferring graphical data between systems, often used in academic and research settings. It facilitates rendering commands and image data transfer over network connections, enabling remote visualization and graphical computing. Though largely obsolete today, understanding ISI-GL provides insight into the evolution of networked graphics protocols..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- unofficial
- risk
- 4/10
- lookups
- 9,363
2 transports registered
payload readable on path
used by convention
caution
rank 511 of 993 · top 51%
Technical Details
what runs on :55ISI Graphics Language (ISI-GL) was developed to enable the transmission of graphical display commands and vector-based images across networked computer systems. It originated at the Information Sciences Institute, supporting experimental remote visualization and interactive computing in the early stages of networked graphics.
Technically, ISI-GL operates over both TCP and UDP ports, allowing it flexible mode selection based on reliability versus latency requirements. It encapsulates graphical primitives and rendering commands, which receiving hosts interpret to display or manipulate graphical objects remotely. The protocol supports basic drawing instructions, user interface elements, and some real-time updates, intended for use over ARPANET and similar research networks.
Due to its vintage, ISI-GL lacks features such as encryption, authentication, or sophisticated error handling present in modern graphical protocols. It is mostly of academic interest or seen in legacy environments, having been superseded by established standards like X11, RDP, and VNC for remote graphics.
Security Information
exposure of :55risk 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
unofficial
used by convention, not registered — what answers here varies by deployment
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Common vulnerabilities with ISI-GL include:
- Lack of encryption, exposing all transferred graphical commands and data to interception or tampering on the network.
- No authentication mechanism, making it susceptible to unauthorized access and man-in-the-middle attacks.
- Potential buffer overflows or implementation flaws in older client/server software.
Common mitigations involve:
- Segmentation of network traffic to restrict ISI-GL communications within trusted zones.
- Wrapping connections in secure tunnels using SSH, VPNs, or other encrypted channels to protect transmitted data.
- Restricting usage to private, isolated testbed environments due to its age and insecurity.
- Replacing with modern, secure alternatives where possible to reduce exposure risk.
Related Ports
the 8 most looked-up other ports in network services — 604 ports carry that label.
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|---|---|---|---|---|---|
| :9080 | Groove RPC | TCPUDP | Web Services | caution | 70.8k |
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| :3268 | Microsoft Global Catalog (GC) | TCPUDP | Security | caution | 54.6k |
| :135 | Microsoft EPMAP | TCPUDP | Security | caution | 51.9k |
| :3128 | Tatsoft Default HTTP Proxy | TCP | Web Services | caution | 46.8k |
risk mix of the 8 listed
- caution100%
0 of 8 encrypted