Im having some major problems with my network. My main PC has a realtek 8139 clone card in it, connected to a clarkconnect linux gateway.

In windows, the main pc is very fast, browses the network at 50k+ speeds (the clarkconnect box is connected to cable internet). However, when I use Mandrake 9.0, 9.1 and just recently Debian 3.0, browsing the 'net is very slow, files download at about 5k/s, and slow down to 300b/s, then stop totally! I have no idea why its doing this, and am pretty sure its my main PC that has the problem. However, I *think* I can access my internal network at normal speeds, so Im stumped.

Also, in Windows when browsing the 'net, sometimes pages fail to load, or stop half-way and need to be refreshed to fully download, which could be because of my gateway pc.

Doing ifconfig on my gateway shows no lost packets or anything.

So, Im not sure where my problem lies, but really want to try and fix it up. Perhaps its a dodgy network card, badly configured something-or-other, or just bad luck?

Could anyone help at all please?

Thanks

Hi,

looks like a MTU problem. Here in germany the German networks are running a MTU of 1500 bytes. If you're masquerading some machines now, and they're sending the packets via the local net with an MTU of 1500 then the packets are gettin to big after they have been masqueraded 'cause the pppoe protocol needs at least 8 bytes in every packet ... for the 2.2 kernels there is a modules called $can't_remember_at_the_moment and for 2.4. kernels you can fix this problem by using iptables:

iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

you need to load the tcpmss module

cu

Both of my machines are running 2.4 kernels Im pretty sure.

Im connecting to the internet by Cable, not adsl, so I dont think it uses the pppoe protocol?

Which machine do I run the iptables command from? Im assuming the clarkconnect gateway?

And what is the tcpmss module used for, and how do I load it? And do I load it before issuing the iptables command?

Thanks

I think I should slap this to my head:

Yup on the gateway ...
It's called tcp_mss.o or tcpmss.o try a

find /lib/modules/$(uname -r) -iname \*mss\*

to get the right name, i can't remember it atm

after that do an

modprobe $module_name


cu

#find /lib/modules/$(uname -r) -iname \*mss\*

gives me:
/lib/modules/2.4.18-18.7.x/kernel/net/ipv4/netfilter/ipt_TCPMSS.o
/lib/modules/2.4.18-18.7.x/kernel/net/ipv4/netfilter/ipt_tcpmss.o

# modprobe ipt_TCPMSS.o
modprobe: Can't locate module ipt_TCPMSS.o

I also edited my modules.conf file, as I thought it may not be pointing there. I added:

path[net]=/lib/modules/'uname -r'/kernel/net


Thanks for all your help so far.

Hi

you can insmod a module with the full path:

insmod /lib/modules/$(uname -r)/kernel/net/ipv4/ipt_tcpmss.o

or by name

insmod ipt_tcpmss

cu

Don't run that command on your cc gateway. If you browse the internet and network on your windows install at high speeds, it is clearly NOT a problem with the CC box. I use CC myself for a router/firewall. It is either a driver or configuration problem on your main box, made evident by the speed shown when browsing with windows.

Zak

Don't fix something that's not broke. You may regret it.

I know, I havent run those commands yet, but I do sometimes get strange things happening in windows.

When browsing, a page will sometimes fail to load, or need to be refreshed as it stops partly loaded. And downloading is limited to ~55k/s, but when it was running straight into my machine, it would get 300k/s+ from some sites.

ie. When using Kazaa, max speed for all connections is 55k/s roughly.

My main pc browsing the 'net doesnt like downloading more than one page at a time, if I have 3 IE windows open, downloading large pages, only one will work at a time.

So, it could possibly be a combination of things, although Im tending to think its a problem with my machines network card in linux, but the above things make me think its got to do with my CC box.

Also, in linux browsing the internal network is fast, getting things off my cc server happens at lan speeds.

I might have to try connecting the internet straight to my main pc in windows/linux and see what connection speeds I get.

You might want to try this:

ftp://152.104.125.40/cn/nic/rtl8139a...inux24x-8139cp(160).zip

That is the driver source files provided by Realtek for the 8139 chip.

I don't know anything about it or how to install it, but there it is. You can find more informatoin @ www.realtek.com.tw

Zak

Are both of your NIC's on your CC box 8139 chips?

I personally use SMC network cards myself. You can get them @ computers4sure.com for pretty cheap, and the work flawlessly in linux with the Tulip driver, and just as well in windows.

In my CC box I have to dlink cards which also work flawlessly.

If you are loosing 5/6 of your internet speed when behind the CC gateway, that's not right. I browse/download at my max cable speed from behind my CC box. You might want to try this...

On your CC box itself, use alt+f2 to get a console, log in and run the lynx command line web browser.
Go to a site and download a file, and see how many K/s you get while downloading in lynx.
If you are still losing 5/6 of your speed, then it is probably a problem with your gateway.
If you are downloading at 300K/s then you know it's a problem on your main box.
It might also be the sites/kazaa that are limiting your speed. Kazaa is not known for 300K/s downloads. In fact, it is quite rare that you find a person sharing that has that much bandwidth. Make sure when you run your download tests that you perform the downloads on the exact same website.

Good luck,

Zak

Thanks, the externel network card was an 8039(?) card, 10mbit.

Ive since reinstalled and put in two 8139 cards, and am getting VERY fast speeds compared to what I had. Im just going out now to jump on that old card....

I dont know why I thought it was my internal networks problem when I could access my LAN at fast speeds, I totally overlooked the fact that it was probably my external network card (eth0).

Now, to try to get wireless working...

Not a problem Glad I could help.