Bittorrent and NAT
david.jenkins at gmail.com
Thu Oct 14 17:11:21 BST 2004
On Thu, 14 Oct 2004 09:56:44 +0100 (BST), Jonathan Belson
<jon at witchspace.com> wrote:
> You can certainly download without port forwarding, but (according to
> the azureus documentation) your download speed will be limited if
> other machines can't connect to you.
> When you're downloading, do you get a yellow smiley or a green one?
> Green smileys mean that you can be connected to from outside, and
> (in theory) you should get better transfer rates.
Hrmm, I get a green smiley even when no-one is uploading of me !?
As a side note, I've tried a lot of bit torrent clients and to date,
Azureus is by far the best - in terms of the interface as well as (and
more importantly) the speed.
I'd definitely persist if you do plan on using bit torrent.
If it helps, here's part of my netstat output from Windows.
TCP 127.0.0.1:6880 0.0.0.0:0 LISTENING
TCP 192.168.0.10:139 0.0.0.0:0 LISTENING
TCP 192.168.0.10:1234 220.127.116.11:6884 ESTABLISHED
TCP 192.168.0.10:1323 18.104.22.168:6881 TIME_WAIT
TCP 192.168.0.10:1334 22.214.171.124:6882 ESTABLISHED
TCP 192.168.0.10:1336 126.96.36.199:27272 TIME_WAIT
TCP 192.168.0.10:1337 188.8.131.52:5000 TIME_WAIT
TCP 192.168.0.10:1345 184.108.40.206:80 TIME_WAIT
TCP 192.168.0.10:1355 220.127.116.11:65535 TIME_WAIT
TCP 192.168.0.10:1357 18.104.22.168:6895 TIME_WAIT
TCP 192.168.0.10:1359 22.214.171.124:6881 TIME_WAIT
TCP 192.168.0.10:1361 126.96.36.199:6881 TIME_WAIT
TCP 192.168.0.10:1367 188.8.131.52:6881 TIME_WAIT
TCP 192.168.0.10:1374 184.108.40.206:6881 TIME_WAIT
TCP 192.168.0.10:1388 220.127.116.11:24861 SYN_SENT
TCP 192.168.0.10:1389 18.104.22.168:6881 SYN_SENT
TCP 192.168.0.10:1390 22.214.171.124:6885 SYN_SENT
TCP 192.168.0.10:1391 126.96.36.199:302 SYN_SENT
TCP 192.168.0.10:1392 188.8.131.52:65000 SYN_SENT
TCP 192.168.0.10:1395 184.108.40.206:6881 TIME_WAIT
TCP 192.168.0.10:1397 220.127.116.11:6881 TIME_WAIT
TCP 192.168.0.10:6881 18.104.22.168:1380 LAST_ACK
TCP 192.168.0.10:6881 22.214.171.124:4076 TIME_WAIT
TCP 192.168.0.10:6881 126.96.36.199:3301 TIME_WAIT
TCP 192.168.0.10:6881 188.8.131.52:3037 TIME_WAIT
TCP 192.168.0.10:6881 184.108.40.206:3189 TIME_WAIT
TCP 192.168.0.10:6881 220.127.116.11:3283 TIME_WAIT
TCP 192.168.0.10:6881 18.104.22.168:3373 TIME_WAIT
TCP 192.168.0.10:6881 22.214.171.124:3671 TIME_WAIT
TCP 192.168.0.10:6881 126.96.36.199:3749 TIME_WAIT
TCP 192.168.0.10:6881 188.8.131.52:3998 TIME_WAIT
TCP 192.168.0.10:6881 184.108.40.206:4120 TIME_WAIT
TCP 192.168.0.10:6881 220.127.116.11:4354 TIME_WAIT
TCP 192.168.0.10:6881 18.104.22.168:4436 TIME_WAIT
TCP 192.168.0.10:6881 22.214.171.124:1893 ESTABLISHED
Note that I am not forwarding port 6881 through my router.
As an experiment I tried the following from an external box to my home box.
$ telnet unixusers.co.uk 6881
Connected to unixusers.co.uk.
Escape character is '^]'.
So my router is somehow letting traffic through on 6881 even though I
haven't asked it to ... !
As a precaution I just tried telnetting the netbios port (139) to see
if my router was somehow misbehaving ... thankfully it wasn't, and the
connection to that port timed out.
As a further test I opened up a random high port and tried telnetting
to that but that failed also.
So I'm not sure why my router is letting through inbound traffic to 6881.
Anyway, I just checked my routers forwarding and it appears it has
just created some rules (since I opened Azureus !)
126.96.36.199 192.168.0.10 tcp 6881
188.8.131.52 192.168.0.10 udp 6881
184.108.40.206 192.168.0.10 tcp 6969
So that's why it's working ... !
After I closed Azureus those rules dissapeared from my port forwarding list ...
(Anyone got any ideas on that ``intelligent port forwarding'' ?)
Sorry, that doesn't really help you though.
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