Bit Torrent Question

[Partial]

Is there any harm in using ports 6881-6899 for bit torrent? I opened them on my router years ago, and the client I just downloaded is mapped by default to something in the 12000 range. Is there a reason for that?

I don't run a firewall or anything, but it is on a linux system so any changes any hacker would want to make would require the super secret code.

[SkinBasket]

the client I just downloaded is mapped by default to something in the 12000 range. Is there a reason for that?

Some ISPs are bottlenecking the 6881-6999 range because they suck cock and are tired of people actually using the bandwidth they're paying for.