If you connect your Motorola Surfboard SB4200 to your computer with a Ethernet (TCP/IP) connection, you need to know a bit more about your computer.
One of the things you need to know are the IP addresses of your modem and computer. For some ISP's you also need to know the DNS IP addresses.
Probably your modem IP address is 192.168.100.1 and if you change your computers IP address to anything in the 192.168.100.XXX range (Subnet Mask 255.255.255.0)
Change in Linux "Network Configuration" the "Default Gateway" Address to 192.168.100.1
Try to find the first and second DNS server IP addresses from your provider, if you still can connect your modem to a Windows computer you can run IPconfig /all to see DNS address.
After this changes (you probably have to restart) you must be able to open your modem setup page (http://192.168.100.1
Probably you can also connect to the internet............
Look at http://adsl.yoll.net/setting-up-adsl...-08-Linux.html
to see some pictures on how-to
With kind regards,