It'a a backdoor. ...

Not necessarily. Port-numbers (above 1024) might be used for any number of [legitimate ...] reasons. What's interesting is when a port is listening for incoming connections: if you don't know what it is or why it's doing that, then it probably should raise at least your curiosity, but it is not ipso facto cause for panic.

If the port-number is being used simply for an active connection, then ... well, for instance, "that's how routers work" (on their Internet-facing side). The port-number that's being used for a connection might have been picked more-or-less at random. Distinct connections simply need to grab a port-number (that's not on that list), and, pretty much, any port-number will do. Port-numbers basically exist to disambiguate multiple connections at the same IP-address.

A protocol will commonly use "a well-known port number" (upon which some service somewhere is listening), to negotiate the terms of a future conversation. Having agreed upon a (random ...) port-number to use, the two parties will then initiate the new conversation. Each such conversation uses its own port. When the conversation ends, the original port-number is forgotten.

9 years for "backdoor"

high number ports are used A LOT now ( 9 years later ) for torrents and i2p and such
i normally set ktorent to use ports in the 40,000 to 65,535 range

isp's do block things using
6881-6889 ,4662, 4672

back in 01 to 07 emule WAS being blocked so 48000 + got used a lot

Mmmm... I think in this case it's actually a backdoor.

By the way, I resumed this ooooold topic - and made some necroposting - because, while searching information about this, for example here:
http://www.computerworld.com/article...ur-router.html
it says this topic was left unanswered, and I could't resist.
Now, it's not unanswered anymore.

No. The OP did not give any relevant details for you to be able to determine that. I'll move your necropost to its own thread.


Since this is your second post in 6 years you might want to work on your problem solving methods.