Static IP, DHCP, and Me...

C. Ed Felt ed at
Thu Feb 3 08:44:03 MST 2005

Some ISPs use the "hostname" as the identifier for security as well as 
the mac address.  If you remember what your old hostname was then use 
the command:
to change your hostname to the one you used before. 
Just "hostname" bye itself tells you the current hostname.
"hostname <new hostname>" changes your hostname.
If that doesn't work, time to sit on hold with tech support :-( .


Bryan Sant wrote:

>I have a static IP from my ISP.  The IP must be acquired via DHCP or I
>can't even ping the default gateway.  The firewall/gateway and DHCP
>server must be in kahoots.
>I had a Gentoo server that was getting the static IP with dhcpcd.  I
>formatted that box and put CentOS 3.4 on that server.  Now when I try
>to get my IP via DHCP I get a temporary IP rather than my assigned IP.
> Obviously the MAC address on my NIC hasn't changed.  Why wouldn't the
>DHCP server identify my MAC and give me my static IP?  I've heard that
>some DHCP clients (Windows?) use a "client ID" rather than the MAC
>address to identify themselves to the DHCP server.  I'm thinking that
>this is what dhcpcd was doing when I was running Gentoo.  I'm using
>ISC's dhclient with CentOS now.
>Is my hunch correct?  Do I need to configure my DHCP client to send a
>client ID instead of my MAC (how do I do that with dhclient?).  Has
>anyone else seen this problem?
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