BitTorrent ports?

[David Timms]

glenn wrote:
> Havard Rast Blok wrote:
>> Hi all,
>>
>> I'm new to the Fedora Test List, so I thought a brief introduction would
>> be appropriate: I'm a European software developer and tester currently
>> working in the QA department of Altova (the XMLSpy company). I've been 
>> using
>> Linux since about Red Hat 5.x and made the switch completely a year 
>> before
>> WinXP. My current pet projects include rememberjava.com and
>> jbookmarks.sf.net.
>>
>> What I wanted to ask you guys about, is BitTorrent, which should be
>> relevant given that Test 3 is now out:
>> http://torrent.fedoraproject.org
>>
>> The question: Which ports should I open to run BT efficiently (and 
>> securely)?
>>
>> My current firewall is rather tight, with as few ports as possibly open,
>> including the range 6881:6999 TCP source and destination ports, plus
>> 33301:34999 on TCP source (not sure if I need those). However, I still 
>> get
>> loads of junk in my /var/log/message from my iptables setup whenever I 
>> run
>> BT. Also, the up and down speeds are rather unimpressive; both about 
>> 10-20
>> KB/s (I'm on a 3 Mb/s cable modem line). Should I open more ports? Should
The cable speed is really a peak speed capability while communicating 
with a local / fast mirror. Once connections are going all over the 
place (peer2peer) this speed probably wont be achievable.

I find azureus bittorent client to suit my needs. It includes things like:
. firewall test
. statistics and graphs on in/out throughput
. azureus wide and per torrent upload and download rate limits
. total and per torrent no of connection limits
all in a nice GUI.
It is common to find is that the outbound data will be flooding your 
internet connection, making it difficult for download ack packets to 
make it out your connection (so the peer sending you data doesn't 
continue until your ack gets through).

Limit upload rate to about half your upload bandwidth, and download to 
90% (if adsl 512 then rate capability is 400kb/sec, *.9 =360).

Also, a lot of home routers have trouble because of the nature of their 
inbuilt firewalls tracking connection states. They have a table of a 
fixed size, and once the table is full, they have to drop/stop 
connections to keep operating. Indeed, some router only last a few days 
or hours once peer2peer clients are operating within the network.

So the other helpful thing to do is limit the number of connections 
total to a smaller number.

I find both of these things improve bittorrent and gnutella peer2peer 
speeds. It does seem weird that limiting your bandwidth can increase the 
achievable speed (it's sort of QOS).

DaveT.