Re: How to make DNS and DHCP server play nice?

[moseley@hank.org]

On Tue, May 27, 2003 at 11:02:48PM -0400, Jerry Quinn wrote:
> Hi, all.  I have a debian box serving as my firewall/router/dhcp
> server.  The dhcp does the job fine, except for dns.
> 
> I'd like to have dns lookups work correctly for my internal network.
> So is there a simple means of having my dhcp clients being able to
> have their names resolve to IP's easily (no or minimal config)?
> 
> I'm not currently running a DNS server but can put one in.  What I've
> read of configuring bind so far makes it sound like a sizable
> investment in time to get working what seems to me to be a pretty
> basic and common desire.

It's like everything else.  It takes days of reading conflicting HOWTOs
that you don't realize until the end that they are for a different
version and reading huge manuals and weeks to let it soak in and looking
over other's config files until it hits you that it's a relatively
simple setup after all and then it only takes a few minutes and it works
fine for a year and then you need to change something and then the
process repeats.

Ok, here's my dhcpd.conf which sets fixed IPs based on MAC address.

default-lease-time 1200;
max-lease-time 7200;

# Empty for eth0
subnet 63.205.225.168 netmask 255.255.255.248 {
}

subnet 192.168.1.0 netmask 255.255.255.0 {
   range 192.168.1.30 192.168.1.50;
   option subnet-mask 255.255.255.0;
   option broadcast-address 192.168.1.255;
   option routers 192.168.1.1;
   option domain-name "hank.org";
   option domain-name-servers 192.168.1.1;
}

host laptop {
    hardware ethernet 00:04:5A:7D:E0:38;
    fixed-address 192.168.1.3;
}

[more hosts]

Then I run bind with "views" (I need to lookup who explained this to me
so I can give credit).  The views make bind give different responses
depending on where the query comes from.  So from inside:

$ nslookup laptop.hank.org
Name:   laptop.hank.org
Address: 192.168.1.3

>nslookup laptop.hank.org
*** can't find laptop.hank.org: Non-existent host/domain

The advantage is that there's little client setup.  If I wasn't running 
bind anyways I'd just use /etc/hosts in each client.

Then I use the "options" part of named.conf that debian setup and then 
do the following.  I'm not bind expert, so hopefully someone else will 
point out any errors.

acl mylan { 
    127.0.0.0/8; 192.168.0.0/24; 192.168.1.0/24; 63.205.225.170; 
};

view "internal" {
        match-clients { mylan; };
        recursion yes;
        notify no;

        zone "hank.org" IN {
                type master;
                file "/etc/bind/hank.org.internal";
        };

        zone "1.168.192.in-addr.arpa" IN {
                type master;
                file "/etc/bind/db.192.168.1.x";
        };
};
view "external" {
        match-clients { any; };
        recursion no;
        allow-query { any; };
        notify yes;

        zone "hank.org" IN {
                type master;
                file "/etc/bind/hank.org";
        };
};

That's not all my zones, but should give you an idea.  I don't see any 
reason you can't do this even if you are not running your own DNS for 
your domain.

-- 
Bill Moseley
moseley@hank.org