Multiple modem disconnections when in Ultra-peer mode

[Larry Nieves]

Hi all,

Everytime I'm running as an ultrapeer my DSL connection will reset more
often than usual. Normally my DSL connection will be reset every 24
hours by my ISP (Freenet), but when GTKG is running as ultrapeer, the
disconnections can be as often as every 30 minutes or every 2 hours.

Currently I have the most recent SVN copy of GTKG (r15971) and I have a
maximum of 20 Ultrapeers and 25 Leaves set. This number I reduced from a
higher one I had before (I believe it was 70 or 80 UP and 100 Leaves),
in the belief that perhaps it was the number of connections being made
that bothered the DSL modem, a Fritz!Box Fon WLan (7113). But reducing
the number of connections hasn't helped a bit and I still get
disconnected every hour or so, sometimes even more quickly.

The most straightforward reason for this behaviour could simply be that
the DSL modem cannot handle the traffic, although when I'm not
downloading or uploading anything, the Gnutella traffic as reported by
the GUI is around 7 kB/s at most in any one direction (I haven't seen it
go higher than that).

Then it could be that my ISP doesn't like gnutella traffic and
disconnects me on purpose.

I don't think this is a GTKG problem per se, since I've seen similar
behavior when downloading files with Bittorrent, but I thought maybe
some of you could help me pinpoint what's the exact problem. How would I
go about finding whether the ISP is disconnecting me, or is the modem
the one failing? I'm glad with some pointers in the right direction and
I would of course do the necesary reading.

Any help would be appreciated.
--
Larry Alexánder Nieves Colmenárez               <lanieves@...>
El Liberal Venezolano            http://liberal-venezolano.net/blog/
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[Raphael Manfredi]

Hello Larry,

Quoting Larry Nieves <lanieves@...> from ml.softs.gtk-gnutella.users:
:I don't think this is a GTKG problem per se, since I've seen similar
:behavior when downloading files with Bittorrent, but I thought maybe
:some of you could help me pinpoint what's the exact problem. How would I
:go about finding whether the ISP is disconnecting me, or is the modem
:the one failing? I'm glad with some pointers in the right direction and
:I would of course do the necesary reading.

How exactly are you connected to the Internet?  Do you perform NAT?

If you do NAT in the DSL modem, it is very probable that the (rather small)
NAT tables of the modem are overflowing quickly and that could cause the
modem to re-initialize your Internet connection (because it panics, for
instance, and reboots internally).

Raphael

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[Larry Nieves]

On Tue, Feb 24, 2009 at 02:32:45PM +0000, Raphael Manfredi wrote:

> Hello Larry,
>
> Quoting Larry Nieves <lanieves@...> from ml.softs.gtk-gnutella.users:
> :I don't think this is a GTKG problem per se, since I've seen similar
> :behavior when downloading files with Bittorrent, but I thought maybe
> :some of you could help me pinpoint what's the exact problem. How would I
> :go about finding whether the ISP is disconnecting me, or is the modem
> :the one failing? I'm glad with some pointers in the right direction and
> :I would of course do the necesary reading.
>
> How exactly are you connected to the Internet?  Do you perform NAT?
>
> If you do NAT in the DSL modem, it is very probable that the (rather small)
> NAT tables of the modem are overflowing quickly and that could cause the
> modem to re-initialize your Internet connection (because it panics, for
> instance, and reboots internally).
>

Hi Raphael,

I have a laptop running behind the DSL modem, which does the NAT and
port forwarding.

I can telnet into the DSL modem, which is running a BusyBox v1.1.2
(linux 2.6.13), but I don't know how to inspect its NAT tables. There's
no iptables command in that environment.
--
Larry Alexánder Nieves Colmenárez               <lanieves@...>
El Liberal Venezolano            http://liberal-venezolano.net/blog/
GPG Public Key: 0x1525843C                                      
Key Fingerprint = 76D0 2DA1 ADA8 11EF 661B  FEE2 923C 050F 1525 843C
gpg  --keyserver hkp://wwwkeys.eu.pgp.net --recv-keys 0x1525843C

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-OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
-Strategies to boost innovation and cut costs with open source participation
-Receive a $600 discount off the registration fee with the source code: SFAD
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[Raphael Manfredi]

Quoting Larry Nieves <lanieves@...> from ml.softs.gtk-gnutella.users:
:I have a laptop running behind the DSL modem, which does the NAT and
:port forwarding.

Then you most probably fall into the situation I was describing.

:
:I can telnet into the DSL modem, which is running a BusyBox v1.1.2
:(linux 2.6.13), but I don't know how to inspect its NAT tables. There's
:no iptables command in that environment.

That's unfortunate. And you'd need to resize them as well.  For instance
passing "hashsize=16384" to the nf_conntrack module.

Either look for a better DSL modem, or configure a dedicated small PC to
be your NAT gateway, with a direct link to the DSL modem (who would then
no longer do any NAT or forwarding, just route the packets to the linux
box).  It's probably best if you can DHCP your linux box to the DSL modem
in that case.

But that requires a much more advanced configuration and understanding
of what is going on so that you can write the proper set of iptable rules
to do what you need.

Raphael

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[Christian Biere]

Larry Nieves wrote:
> On Tue, Feb 24, 2009 at 02:32:45PM +0000, Raphael Manfredi wrote:
> > Quoting Larry Nieves <lanieves@...> from ml.softs.gtk-gnutella.users:
> > :I don't think this is a GTKG problem per se, since I've seen similar
> > :behavior when downloading files with Bittorrent, but I thought maybe
> > :some of you could help me pinpoint what's the exact problem. How would I
> > :go about finding whether the ISP is disconnecting me, or is the modem
> > :the one failing? I'm glad with some pointers in the right direction and
> > :I would of course do the necesary reading.

The first thing to consider is checking the configured bandwidth limits in
your applications, especially upload bandwidth. Make sure you haven't
confused "bits per second" with "bytes per second". If your outbound queue
gets too clogged, this can cause monitoring timeouts with DSL over PPPoE
and terminate your connection. So you better configure your applications to
use not more than 80% of your assumed upload bandwidth. You might want to
monitor the actual bandwidth use with netstat (or something like gkrellm).

Keep in mind though that your router might see much more traffic that
never makes it to your laptop.

> > How exactly are you connected to the Internet?  Do you perform NAT?
> >
> > If you do NAT in the DSL modem, it is very probable that the (rather small)
> > NAT tables of the modem are overflowing quickly and that could cause the
> > modem to re-initialize your Internet connection (because it panics, for
> > instance, and reboots internally).

You might want to check its uptime. It's also possible that it gets too
warm or that the memory is defect. If it's acceptable for your purposes
to use ethernet LAN instead of WLAN, try that too.

> I have a laptop running behind the DSL modem, which does the NAT and
> port forwarding.

If you had a "DSL modem", you wouldn't have a problem, but you have a router
(with a modem built-in it seems). You've configured a portforwarding for the
port your gtk-gnutella uses for both TCP and UDP, right? gtk-gnutella does
not support UPnP. If you don't need UPnP otherwise, it's best to disable it.

What you could further try is disabling the firewall on this router assuming the
devices behind don't expose any services that shouldn't be accessible
externally. Most-likely this router has far too little memory to act as
reasonable stateful firewall.

Another thing you could /try/ is disabling UDP for gtk-gnutella /temporarily/.
While it's an extremely bad idea in general, it would help you see whether
this makes a difference for your router. If it helps, this most likely
means the resources of your router are insufficient i.e., the NAT tables
for UDP get too big.

Maybe your router has a DMZ feature which would expose all ports of laptop
and make NAT tracking unnecessary.

--
Christian

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