On a Linux Apache server, from time to time, there are messages saying TCP: Treason uncloaked!.

There are previous questions on ServerFault explaining the fixes for this issue.

However does anyone know the meaning of this error message? Why would mis-matched TCP messages provoke such an unclear error message? Has this message got some history behind it?


It's part of a long tradition of attempts (and successes) at humor in Unix and Linux error messages. It simply means that a TCP window was shrunk unexpectedly.

  • As traditions go it's more annoying than useful. These messages can fill the kernel log buffer pretty quickly on a busy internet-facing host. – Gerald Combs Jul 26 '10 at 15:31
  • Seems like we were being attacked by Slowloris - now I class this error message as a good indication of attack (ha.ckers.org/slowloris). – Metalshark Jul 26 '10 at 15:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.