Static IP, DHCP, and Me...

Dan Egli dan at
Wed Feb 2 21:05:17 MST 2005

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?

This is somewhat similiar to experiences I'm dealing with, and have yet 
to resolve. Everyone keeps telling me that they use Linux and either 
dhclient or dhcpcd to get their IP from Comcast. But ever since I did a 
silly thing and tried to assign multiple dhcp addresses to the same 
physical card (I don't even remember WHY now), no linux machine in my 
house has been able to obtain a DHCP address. I've tried all 3 clients 
(pump, dhcpcd, dhclient) to no avail, I've tried different network 
cards, heck I've even tried different COMPUTERS! Every time, if the 
computer is Linux, it fails. If not, it works great. Windows gets an 
address and even my Wireless router gets an address. But a Linux 
computer? Heck no!

Now if anyone can figure this one out, I'll be VERY greatful! As it is I 
have to have 2 networks to get the type of firewall customizibility I 
want. There's the outside network, which goes from the wireless router 
to the linux firewall (and of course includes any wireless machines), 
then from the Linux firewall on back is the "inside" network. I'd LOVE 
to consolidate these into one network!

-- Dan

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