Fetching torrents kills my wlan.

akejo · 2008-12-29 21:23:32

Hello all.

I have a small mystery I can't seem to solve. It is about torrents and my wlan(How my wlan is setup is shown in another thread below(http://bbs.archlinux.org/viewtopic.php?id=61071) ).

I used utorrent(via wine) to download one torrent just as a test. It seemed to work ok, but as I like to have a native client instead of wine/utorrent I pac'd Deluge and started it up. Using same network(and directory) settings as utorrent I saw my freshly downloaded torrent in deluge and it started to seed it. I continued to add another file and it connected to the peers and then ... nothing.

I experienced firefox loosing contact with this site among others and I did a check using iwconfig/ifconfig. They turned out ok as seen below.

wlan0     IEEE 802.11g  ESSID:"BEGONE"  
          Mode:Managed  Frequency:2.437 GHz  Access Point: 00:19:CB:05:47:39   
          Bit Rate=54 Mb/s   Tx-Power:-2147483648 dBm   Sensitivity=0/3  
          RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality:57/100  Signal level:-59 dBm  Noise level:-96 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

wlan0     Link encap:Ethernet  HWaddr 00:19:CB:00:FB:F5  
          inet addr:192.168.1.3  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:510640 errors:0 dropped:0 overruns:0 frame:0
          TX packets:501054 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:455859184 (434.7 Mb)  TX bytes:233436549 (222.6 Mb)

I then checked the logfiles and in messages.log I saw the following

Dec 29 21:56:07 apc possible SYN flooding on port 65534. Sending cookies.
Dec 29 21:57:08 apc possible SYN flooding on port 65534. Sending cookies.

I could use iwlist to see the access points so scanning worked. Using /etc/rc.d/net-profiles restart only resulted in a message saying it couldnt re associate interface, after a reboot it was all ok again.

Below is my card

Dec 29 22:04:05 apc ndiswrapper version 1.53 loaded (smp=yes, preempt=yes)
Dec 29 22:04:05 apc usb 1-3: reset high speed USB device using ehci_hcd and address 2
Dec 29 22:04:05 apc ndiswrapper: driver wlangzg (ZyXEL Communications Corp.,08/08/2007,1.7.1.4) loaded
Dec 29 22:04:05 apc wlan0: ethernet device 00:19:cb:00:fb:f5 using NDIS driver: wlangzg, version: 0x1070104, NDIS version: 0x501, vendor: 'ZyXEL G-202 Wireless USB Adapter', 0586:3410.F.conf
Dec 29 22:04:05 apc wlan0: encryption modes supported: WEP; TKIP with WPA, WPA2, WPA2PSK; AES/CCMP with WPA, WPA2, WPA2PSK
Dec 29 22:04:05 apc usbcore: registered new interface driver ndiswrapper
Dec 29 22:04:05 apc atl1 0000:02:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
Dec 29 22:04:05 apc atl1 0000:02:00.0: version 2.1.3
Dec 29 22:04:05 apc usbcore: registered new interface driver zd1211rw

Now.. I'm not sure where to go from here. How I can I make sure deluge isnt killing my connection, is there a threshold in the interfaces I should increase(max open connections?). The log files don't show much, deluge log seems to be ok. Same problems have occured with transmission and few other clients so I suspect its my wlan that cant handle the load, but where do I poke next to make sure it can handle some load and not die when it gets a bit busy?

Any tips on where to look next to help me use deluge without fearing the network drop is welcome.

Last edited by akejo (2008-12-29 21:25:20)

Super Jamie · 2008-12-29 21:59:29

What sort of router do you have? Most home-quality routers have weak little CPUs and can't handle massive amounts of TCP connections on top of establishing PPPoE/PPPoA and encrypting all your stuff in WPA/WPA2.

The settings I use are:
- Max Connections 50
- Max Upload Slots 8
- Max Half-Open Connections 8
- Max Connection Attempts per Second 8
Which seems not to tax my little WRT54GL too heavily, whilst still providing decent torrenting ability. Also, map a port range to your PC, don't use UPnP. Having a good router which you can set TCP timeout on definitely helps, keep it fairly low if you can, 5 minutes is good enough. The default is often up to an hour, which fills your router's memory with an absolute HEAP of connections you used to download one piece of a torrent with, then will never touch again.

Bandwidth-wise, you can set max download to be fairly close to your actual max download speed. Max upload should be about 50-75% of your connection capability. So if you have ADSL2+ with 24Mbps down and 1Mbps up, your max upload is (theoretically) about 100kb/sec, so set your Deluge max upload to about 50-75kb/sec. That's the thing which usually kills people's connections while torrenting.

Bittorrent is a fairly inefficient protocol. Even if Deluge "says" you're uploading at 30kb/sec, that's just actual traffic. Because of the nature of torrents (many concurrent TCP connections to many hosts) you get alot of overhead, in such a circumstance you're probably using closer to 40kb/sec of actual bandwidth.

Last edited by Super Jamie (2008-12-29 22:00:39)

akejo · 2008-12-29 22:12:38

Thanks for your response Super Jamie.

I got a Zyxel P-320W router(Free offer from Telia ), and I have mapped a ports 65534-65535 to my pc. The router itself don't have much more settings then just a few, but it have done its job quite ok this far.

The thing is, the settings I have in my router havent been changed in the last 4 months and I used Torrentflux on my server(before the old pc/server died of old age.) with atleast 5-6 torrents active simultaneously, my family used utorrent on their windows pc's(on wlan in Windows) downloading stuff at the same time as my server downloaded. The little itsy bitsy router seems to have handled the load quite ok there(though I miss my ancient, now diseased, netgear beast I had a few years back).

I will try change Deluge settings to the ones you propose, then see what happens. Its to bad the logs don't show very much info on what is gong on

akejo · 2008-12-30 11:44:51

Here we go again...

I've tried the settings proposed, I've used several clients and still get the same result. While my wlan drops my family can continue use the net, both using the same wireless router I am. I am certain there's a 'flood setting' somewhere in my installation that is causing the problem and not the network/router itself.

Does anyone else have or have had the same problems with 'flooding' in arch and solved someway?

Super Jamie · 2008-12-30 22:33:30

I'd look more at the limitations of the windows driver when loaded into ndiswrapper, or limitations of USB bandwidth (I gather from the above that your wireless NIC is USB).

Do you have cabled ethernet on the PC you're using? Are you able to try disabling wireless and torrenting over a network cable temporarily instead? That'll at least tell you if it's a wireless issue or not.

Networking setup is pretty basic, and torrent clients (should) just do what they're told. I doubt there's a setting like mess_up_my_wlan_but_nobody_elses=1 in /etc/rc.conf or something

kludge · 2008-12-31 00:20:56

Super Jamie wrote:

I'd look more at the limitations of the windows driver when loaded into ndiswrapper, or limitations of USB bandwidth (I gather from the above that your wireless NIC is USB).
Do you have cabled ethernet on the PC you're using? Are you able to try disabling wireless and torrenting over a network cable temporarily instead? That'll at least tell you if it's a wireless issue or not.
Networking setup is pretty basic, and torrent clients (should) just do what they're told. I doubt there's a setting like mess_up_my_wlan_but_nobody_elses=1 in /etc/rc.conf or something

a friend of mine who runs "that noobie distro" was experiencing random, un-called-for hardware reboots on a cabled connection. after weeks of scratching his head over the every-day-or-so reboots, he quit seeding all those torrents. and... his uptime is now 9d14h. my guess is that these two cases are related, probably having to do with network drivers responding *real* poorly to excess connection attempts.

but... that's about as far as insight carries me.

Last edited by kludge (2008-12-31 00:23:32)

Arch Linux

#1 2008-12-29 21:23:32

Fetching torrents kills my wlan.

#2 2008-12-29 21:59:29

Re: Fetching torrents kills my wlan.

#3 2008-12-29 22:12:38

Re: Fetching torrents kills my wlan.

#4 2008-12-30 11:44:51

Re: Fetching torrents kills my wlan.

#5 2008-12-30 22:33:30

Re: Fetching torrents kills my wlan.

#6 2008-12-31 00:20:56

Re: Fetching torrents kills my wlan.

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