3. Configuration

3.2.1. Manually Assigning MAC to Interface Name

Whatever distribution you use, you can always use the command line to designate an Ethernet device (via the MAC) to be interface 'ethX' with or without a particular IP address. This may be necessary when you change your settings, swap out hardware or for just plain testing. Use ifconfig:

# ifconfig ethX hw ether 00:D0:09:DE:D4:6F up 

You can check if it worked by calling ifconfig without options after your next reboot. See man ifconfig for more options.

3.2.2. Automatic Configuration of Devices

The method for automatically assigning a particular interface name ethX, to a specific hardware interface (Media Access Control address) differs by distribution.

	# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8) # The
	loopback interface auto lo iface lo inet loopback auto eth0 iface eth0 inet
	static address 192.168.1.1 netmask 255.255.255.0 network 192.168.1.0 hwaddress
	ether 00:D0:09:DE:D4:6F

	auto eth1 iface eth1 inet dhcp hwaddress ether 00:04:BD:DE:42:0B

 DEVICE=eth1 
# Device name. This is the interface your cable modem will use.  
ONBOOT=yes 
# load at boot BOOTPROTO=dhcp 
# sets the device to receive an IP address from a DHCP server 
HWADDR=00:04:BD:DE:42:0B 
# the hardware MAC 

3.3.1. USB CDCEther

If you wish to use the USB interface to accept data you will need USB subsystem support in your kernel as discussed in Section 2.1, whether USB-ohci, USB-ehci, or whatever USB host controller driver required by your system. For a more in-depth discussion of this, I direct you to the Linux-USB project site.

In addition the CDCEther (Communications Device Class Ethernet) protocol common to cable modems.

There are two ways your kernel may support a device driver: either by being statically (always on) compiled within that kernel or loaded (at boot time or later by a script or manually) as a module. You can find out if a driver is statically compiled in the kernel by checking the log of messages at boot up using dmesg | less on the command line. Experienced users may want to take an easier route and check the configuration file for the currently running kernel in /boot, usually of the form config-2.X.x, which is a text file that can be grepped. On the command line, try grep -e followed by CONFIG_USB_CDCETHER in 2.4.x kernels or CONFIG_USB_ETH in 2.6.x kernels followed by the filename; you should see a '=y or =m at the end of this string for static or modular status, respectively.

The output of dmesg | less should reveal something similar to the following

 Mar 2 11:00:52 K7 kernel: CDCEther.c:
0.98.6 7 Jan 2002 Brad Hards and another
Mar 2 11:00:52 K7 kernel: usb.c: registered new driver CDCEther 

in the case of a statically compiled driver or a module loaded at boot.

If you don't see it, to find out if your kernel has already loaded the CDCEther (Communications Device Class Ethernet) driver as a module, on the command line issue lsmod as root. You should see the module CDCEther listed for 2.4.x kernels, or alternatively usbnet for 2.6.x kernels.

If you don't see it listed with lsmod try loading the module directly as root; for kernel 2.4.x this would be of the form

 # modprobe CDCEther 

 # modprobe usbnet

If all goes well you should see something like the following at the end of your system log files (/var/log/messages or /var/log/syslog, you may need to be root to view these) or at the end of dmesg | less from the command line:

 Mar 2 11:00:52 K7 kernel: CDCEther.c:
0.98.6 7 Jan 2002 Brad Hards and another
Mar 2 11:00:52 K7 kernel: usb.c: registered new driver CDCEther 

If all goes well you should see something like the following in your system log files or at the end of dmesg:

 Mar 2 11:00:52 K7 kernel: CDCEther.c:
0.98.6 7 Jan 2002 Brad Hards and another 
Mar 2 11:00:52 K7 kernel: usb.c: registered new driver CDCEther 

If you are unsuccessful with any of the above, and are determined to use the USB conduit of this device, you will need to recompile your kernel to support it. You will need the 2.4.3 kernel or later. For detailed instructions on recompiling your kernel, I direct you to the Kernel-HOWTO. The options required to get USB interface support working on this device have been addressed in Section 2.1.