C# Watchdog for thread?

Question

C++ / C#

A MITM proxy server is being written using NetworkStream and SslStream.
The problem is that NetworkStream doesn't signal connection close (callback or exception).
For example, a request "proxy server" has been processed and is waiting for the Web server to respond ( NetworkStream.Read ), or it's set to Connection: keep-alive and you need to keep the connection, or the situation when the channel is slow and receiving data takes a long time, in general, it doesn't matter if it takes a long time work as a Web server via NetworkStream/SslStream. And the client NetworkStream closed (timeout or browser tab closed).
I see an option, when processing a new client NetworkStream, to start monitoring it in a separate thread for an exception with a zero write to the stream (as recommended by MSDN).
From here the question is how to complete the parent thread from the child thread.

Answer 1

how to terminate parent thread from child thread.

Threads do not have a parent/child relationship. End accordingly as always:

var parentThread = new Thread(..
...
parentThread.Abort();