> Upon examing the source of file htscatchurl.c, line
> 67 in the code shows a few listening ports. One of
> them being 31337, which is commonly known for
> trojans and malware. Why is HTTrack listening on
> this port?
"Catch URL" is used when you click in the GUI on "Add URL" / "Capture URL". It
allows to capture through a temporary proxy a POST form, and use the result to
mirror it (example: a login form you want to mirror - there is no "URL" per
se, but a POST request with fields - something httrack can mirror with some
help).

To select the temporary proxy port, httrack attempts to listen to the first
available port related to proxies (8080, 3128...), including 31337, mostly for
fun.

The "try_to_listen_to" variable is pretty transparent
(https://code.google.com/p/httrack/source/browse/trunk/src/htscatchurl.c#67)