Re: Need help w/ dhcpd and shared-network option . . .
Jeff Vincent, 2001-Dec-11 19:25 -0700:
> There are no other routers between the subnets that I know of.
>
> When we configure our machines statically, all use the same static
> route at address X.Y.D.254 (same as static route?) and all use the same
> subnet mask of 255.255.252.0 regardless of subnet and has been that way
> for nearly 2 years. (netmasks have always been a bit of voodoo magic
> for me anyway (see question below)— ack!) However, our IS dept. told
> us to use that subnet mask and additionally delegated us a domain and
> the 4 class C subnets for our testing use. At least I thought they were
> class C address blocks:
>
> X.Y.A.[0-255]
> X.Y.B.[0-255]
> X.Y.C.[0-255]
> X.Y.D.[0-255]
>
> where the '0' is the network and '255' is the broadcast address.
Okay, so the the mask you are using actually makes those four
blocks into a single subnet. So, you don't have for routable
subnets configured, you have a single subnet of ~1000 host
addresses, a single network address of X.Y.A.0 and a single
broadcast address of X.Y.D.255. This is generally not a good
idea for several reasons, but it's obviously functional.
To make those four Class C blocks into four subnets, you'd need
to change the mask to 255.255.255.0 and you'd need to do some
routing.
> If I change the netmask to 255.255.252.0 I get this message:
>
> No subnet declaration for eth0 (151.155.155.252).
> Please write a subnet declaration in your dhcpd.conf file for the
> network segment to which interface eth0 is attached.
> exiting.
>
> I then added an additional subnet declaration for <subnet4> inside the
> shared-network section but with no range (we don't want any of this
> subnet in the dhcp pool) and now it seems to work. I am most confused.
Ah! I didn't catch that the first time. Yeah, you have to
declare all interfaces that the system has configured. Dhcpd
checks them all and shouldn't even start the daemon if there is a
configured interface that is not declared. The range is needed
only if you want to serve addresses on that interface.
> Maybe I need to really figure out the netmask thing. Is the netmask
> that is part of the subnet declaration different from the 'option
> subnet-mask' statement?
Yeah, this is getting a bit tricky since you've got such a huge
subnet. I'll post any ideas that might occur to me.
jc
--
Jeff Coppock Systems Engineer
Diggin' Debian Admin and User
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