I have install RHEL AS 4 update 3 on a machine. When plug in a cable to the intel 1G eth port (the otherside is connected to a router), everything works fine. But when I unplug the cable, run ifconfig -a shows no eth0 and corresponding MAC address. So the machine only shows eth (MAC address) when there is a working eth connection. Is that normal? I need to use the MAC address when there is no eth connection. Thanks.
mmm that shouldn't be right, actually you dont need that MAC address, the router ask for it.
You can look in for the router to catch you MAC address, try looking at the router addresses or the mac table if you hace a switch somewhere, the other way is to look up the arp table in your router.