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Old 04-16-2003, 10:24 AM   #1
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Setting up USB Cable Modem

I've just installed Mandrake 9.1 but am having the same problem as most people who try to install a USB Cable Modem.

I've read somewhere that I may need to activate the USB modem support in the kernel. The problem is that I can't seem to run xconfig as I keep getting a problem with permissions.

Can anyone shed some light on this for me?
Old 04-16-2003, 11:00 AM   #2
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How are you trying to run xconfig, from the /usr/src directory and as root? Have you tried running "make menuconfig" as well to see if that works? If you can provide the exact error, it might get quicker responses.
Old 04-16-2003, 04:15 PM   #3
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First of all, yes, you need to enable USB support in the kernel. No matter how you do your kernel configuration (xoconfig, menuconfig, or whatever), you should go to the category 'USB DEVICES' and then activate "USB Communication Class Ethernet device support" (notice the "EXPERIMENTAL"). The module which communicates with the cable modem via USB is 'CEDCEther.o'.

In my case, SuSE 8.1 has misconfigured some some USB description files and the module does not load automatically. I load it manually (modprobe CDCEther). I tried the new experimental SuSE kernel, but now it loads the module 'acm', which is used by dialup USB modems and has nothing to do with cable modems (so I run a 'rmmod acm' and then 'modprobe CDCEther'). Of course, to run 'rmmod' and 'modprobe' you need to have root privileges (or have the /etc/sudoers file suitably arranged to run those commands with a 'sudo' in front of them, which will give you root privileges for those commands only).

The CDCEther driver may have some problems with buffer overruns, as I read in sourceforge. Actually, the problems may actually be with the kernels which do not support buffers large enough for this application. This problem may be solved by the 2.4.20 and newer kernels.

You must run 'make xconfig' as ROOT and from the directory '/usr/src/linux', which is soft-linked to '/usr/src/<whatever subdirectory your new kernel is in>'.

Hope all this helps.
Old 04-16-2003, 05:06 PM   #4
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Managed to get xconfig to work. In Mandrake 9.1 the 'root' user option isn't automatically available on the login screen. Only found out how to activate it by running through each of the many configuration progs.

However I notice that the USB modem option is automatically selected as a module. So now I need to figure out where to go from here.

My copy of Mandrake has the 2.4.21 kernel in case that's any use to anyone.

I'll fiddle about some more with it.
Old 04-16-2003, 06:13 PM   #5
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Having CDCEther compile as a loadable module is fine. You need to compile your kernel with this option enabled and then hook up the USB connection to the cable modem (after booting the new kernel). Run an 'lsmod' after connecting the the calbe modem to the USB port. If the module 'CDCEther' doesn't show up, you can load it up manually by 'modprobe CDCEther' (you need to have root privileges to do this).

As I described in post above, you should make sure you are not trying to load the 'acm.o' module, which is used for DIALUP USB modems. Make sure that you enable the correct drivers in the kernel as I described in my previous post above. (The 'acm.o' module may have other uses, too, as many 3G cellphones look like USB modems to the Linux kernel, but it has nothing to do with cable modems. 'CDCEther.o' is the module you need for the cable modem to connect via USB.)
Old 07-30-2003, 07:12 PM   #6
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I have a similar problem.. I'm running Mandrake 8 and using a Motorola SB4200 Cable Modem using USB. I've tried a few things that people have told me to do (i'm a newbie) and it doesn't seem to work. When I type 'lsmod' it shows CDCEther as a module and I've also loaded it manually but it doesn't seem to work. My modem is listed as Unknown in Harddrake. I'm not sure what other info anyone would need but I'm in desperate need of help.

Last edited by IbanezS; 07-30-2003 at 07:51 PM.
Old 07-31-2003, 09:18 AM   #7
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in an xterm window type:

ifconfig -a

This should come out with something like:

eth0: USB Cable Modem etc

This means that the CDCEther module has loaded.
Now type


If the modem is communicating with the internet, it should appear again, if not, as root, type:


then try


again. Hopefully eth0 will have an IP address and internet access is available
Hope this helps, Sam


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