How to configure the dhcp server for a laptop

Marc Chamberlin marcc at easystreet.com
Tue Jul 10 00:52:23 UTC 2007


Hello -  I know this may go a bit beyond the pale for most users but I 
need help configuring my home network dhcp server....

I have a dual boot laptop that I use between multiple work sites and 
home. This laptop is configured to boot up either in Windows Vista or 
SuSE Linux and has two network connections - wired and wireless. Because 
I am constantly moving around from one network to another I must leave 
the laptop configured so that it receives it's IP address dynamically 
from a local DHCP server and cannot configure it to use a fixed static 
IP address.

What I need my home DHCP server to do is to assign my laptop one 
particular IP address if it boots up in Windows and another if it boots 
up in Linux, regardless of which network connection (wired or wireless) 
that I choose to use when I get home. (This is so disk mounts, and other 
programs running on my home network will work properly when my laptop 
enters my home network environment. Also I frequently switch between 
wired and wireless mostly for performance purposes when transferring 
large files but also for remote control operations.) For each OS, I do 
assign the laptop a different host name, depending on which OS is 
booted, to help identify it, but I cannot understand the DHCP server's 
model well enough to figure out how this would help, though it seems it 
should..

So in a nutshell I want -

OS          medium   MAC addr               IP Addr
Linux       wired      aa:aa:aa:aa:aa:aa       192.168.2.10
Linux       wireless   bb:bb:bb:bb:bb:bb    192.168.2.10

Windows wired      aa:aa:aa:aa:aa:aa        192.168.2.20
Windows wireless  bb:bb:bb:bb:bb:bb      192.168.2.20

I searched through the archives and found one suggestion for configuring 
dhcpd.conf for using two interfaces on a laptop so as to
get the same IP address assigned to each, but that approach seems to 
ignore the actual name given to the laptop. It was suggested to 
configure it with unique DHCP host names for each MAC address as follows -

group {
    host laptopname_wired {
         hardware    ethernet  aa:aa:aa:aa:aa:aa;
         fixed-address 192.168.2.10;
    }
    host laptopname_wireless {
          hardware   ethernet  bb:bb:bb:bb:bb:bb;
          fixed-address 192.168.2.10
    }
}

I guess I am thoroughly confused by the DHCP server's model of computers 
on a network. Does it not use both the name of the laptop as supplied by 
the laptop AND the MAC address of the interface to uniquely identify it? 
I thought the following might work but it gives me an error instead 
apparently because the host names are not completely unique....

group {
    host laptopname_linux {
         hardware    ethernet  aa:aa:aa:aa:aa:aa;
         fixed-address 192.168.2.10;
    }
    host laptopname_linux {
          hardware   ethernet  bb:bb:bb:bb:bb:bb;
          fixed-address 192.168.2.10
    }
    host laptopname_windows {
         hardware    ethernet  aa:aa:aa:aa:aa:aa;
         fixed-address 192.168.2.20;
    }
    host laptopname_windows {
          hardware   ethernet  bb:bb:bb:bb:bb:bb;
          fixed-address 192.168.2.20
    }
}

In this configuration file, does/must the name following the host 
parameter actually correspond to the actual name given to a computer on 
the network served by the DHCP server? If so, then must the name given 
to a computer change, for each interface actually used, to accomplish 
what I want to do? If so, I have no idea how to accomplish that!  Or are 
these just identifiers used internally by the DHCP server? If that is 
the case, then is there some other means of using two (or more) 
"identifiers" (MAC addresses being one of them) to allow the DHCP server 
to identify and assign fixed IP addresses to the client based on such 
combinations?

I have no idea how to determine what the version of the DHCP server I am 
using is, it is what came with SuSE10.1
I am by no means an expert on networking or DHCP servers so any step by 
step guidance in simple terms would be greatly appreciated! Thanks in 
advance...

    Marc...




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