First Time with Groups

[Simon Hobson]

Matt Neimeyer wrote:

>I set up a dhcp 3.1.2 server on my Gentoo box the other day and I'm
>trying to set it up so that my "unified" network in the house has
>three computers using the office DSL router and the rest using the
>home DSL router. The three office PCs are statically assigned and all
>but one of the home PCs are dynamic. I know I could do seperate
>subnets but I've got enough shared resources between the two that I'd
>prefer not to go that route if I can avoid it. (NAS devices, printers,
>etc)
>
>If I've read the various man pages right I should indicate all devices
>in the conf file but I'm not sure how I should represent devices that
>are "self contained" with a set IP. For example, the DSL routers and
>the one switch I have. (10.1.1.1, 10.1.1.254 and 10.1.1.2
>respectively)

You don't do anything for devices you aren't configuring via DHCP - 
there is no need to.

Turning to your config, you have several errors, not least of which 
is that host statements are global and should not be within a subnet. 
Also, putting a range statement in a group doesn't help.

Try this :

subnet 10.1.1.0 netmask 255.255.255.0 {
   # // Residential
   range 10.1.1.100 10.1.1.200
   router 10.1.1.254
}

# Residential
group {
   # router 10.1.1.254 ; - redundant as it's the subnet config
   host omega {
     hardware ethernet 00:00:sa:mp:le:01;
     fixed-address 10.1.1.5;
   }
}

# Business
group {
   router 10.1.1.1 ;
   host alpha {
     hardware-ethernet 00:00:sa:mp:le:02;
     fixed-address 10.1.1.6;
   }
   host beta {
     hardware-ethernet 00:00:sa:mp:le:03;
     fixed-address 10.1.1.7;
   }
   host gamma {
     hardware-ethernet 00:00:sa:mp:le:04;
     fixed-address 10.1.1.8;
   }
}


By default, any hosts not configured otherwise will get an address 
from the one pool - and the residential router as their gateway.

Host Omega will get the fixed address specified and any options 
specified in teh group statement. In practical terms, none are 
required since the router specified is the same as the default router 
for the subnet. In this case, the group statement is redundant since 
there aren't any group specific options to set, and there's only one 
member anyway.
If you don't actually need a fixed address, then you could simply 
omit the host entry for omega altogether.


The three hosts alpha, beta, and gamma will get the alternative 
router specified in the group statement, and the fixed addresses 
specified. Note that they don't actually have to have a fixed 
address, it's OK to let them have dynamic addresses.

The group statement is really just a shorthand way of applying a set 
of config statements to multiple hosts. The end results are the same 
as writing :

host alpha {
   hardware-ethernet 00:00:sa:mp:le:02;
   fixed-address 10.1.1.6;
   router 10.1.1.1 ;
}
host beta {
   hardware-ethernet 00:00:sa:mp:le:03;
   fixed-address 10.1.1.7;
   router 10.1.1.1 ;
}
host gamma {
   hardware-ethernet 00:00:sa:mp:le:04;
   fixed-address 10.1.1.8;
   router 10.1.1.1 ;
}


-- 
Simon Hobson

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