# Systat (protocol)

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Systat_(protocol)
> Markdown URL: https://mediated.wiki/source/Systat_(protocol).md
> Source: https://en.wikipedia.org/wiki/Systat_(protocol)
> Source revision: 1313112942
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

**Systat** or **Active Users** is a simple [Internet](/source/Internet_Protocol_Suite) protocol ostensibly useful for "debugging and measurement".[1] A connection to port 11, by either TCP or UDP, elicits a list of users currently logged into the system. Though it remains an official Internet protocol, its use is considered a security vulnerability.[2]

## References

1. Postel, J. (May 1983). "Active Users". [IETF](/source/Internet_Engineering_Task_Force)

1. ["systat and netstat"](http://etutorials.org/Networking/network+security+assessment/Chapter+5.+Assessing+Remote+Information+Services/5.2+systat+and+netstat/). eTutorials.

---
Adapted from the Wikipedia article [Systat (protocol)](https://en.wikipedia.org/wiki/Systat_(protocol)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Systat_(protocol)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.