dhcpd and dns

[sputnik]

Hi.

My openbsd machine is firewall/gateway and dhcp server for other computers at my office. Now the computers uses ISP dns for resolving hostnames, but i'd like them to use my openbsd for name resolving. So i can change
"option domain-name-servers dns.of.my.isp;" to
"option domain-name-servers 192.168.1.1;",
which is the address of openbsd internal interface, but that's not enough, though. Is there something i'm missing in resolv.conf, or i just have to run named for such intentions?

Thanks.

[jggimi]

It should work, unless there's some other problem with your configuration.

Here's an example excerpt from a fairly simple SOHO configuration. The "routers" option is in the subnet as this router provides DHCP to multiple NICs:

option domain-name "example.com";
option domain-name-servers 192.168.1.1;

subnet 192.168.1.0 netmask 255.255.255.0 {
             option routers 192.168.1.1;
             range 192.168.1.100 192.168.1.200;
}

[sputnik]

Hm, but it doesn't..
There's mine:

shared-network LOCAL-NET {
        option  domain-name "my.hostname.it";
        option  domain-name-servers 192.168.1.1;

        subnet 192.168.1.0 netmask 255.255.255.240 {
                option routers 192.168.1.1;
                range 192.168.1.2 192.168.1.14;
                default-lease-time 86400; #24h
                max-lease-time 172800; #48h
        }
}

[jggimi]

Clients can override server "recommendations" -- if the clients are still pointing at your ISP's DNS address(es), I'd look at your client configurations.

[sputnik]

It's ok with clients configuration, i mean client gets 192.168.1.1 as dns server. The problem is the server doesn't resolves hostnames. I mean server it self doesn't work as resolver...

[BSDfan666]

You'll need to configure a recursive DNS server like BIND.. or something similar from the ports tree.

[sputnik]

I thought so, so i've started bind with default configuration adding only one line to named.conf

forwarders { dns.of.my.isp; };

and now it resolves hostnames, but syslog gives an error messages like this, though it works as i wanted...

May  7 11:59:54 myhostname named[27303]: client 192.168.1.6#1026: RFC 1918 response from Internet for 6.1.168.192.in-addr.arpa
May  7 12:45:35 myhostname named[27303]: client 192.168.1.5#1025: RFC 1918 response from Internet for 5.1.168.192.in-addr.arpa

Could i get rid of this messages somehow?

[BSDfan666]

BIND is forwarding the lookup of IN-ADDR.ARPA zones to your ISP's DNS server, this isn't the proper way of doing it.

You can create your own master zone to get around this,
/var/named/etc/named.conf

...
zone "1.168.192.in-addr.arpa" {
    type master;
    file "master/1.168.192.in-addr.arpa";
};

/var/named/master/1.168.192.in-addr.arpa

$ORIGIN 1.168.192.in-addr.arpa.
$TTL 24h 

@	IN	SOA	mydomain. root.localhost. (
			2009050801	; serial
			8h	; refresh
			2h	; retry
			10d	; expiration
			24h )	; minimum

		NS	mydomain.
1	IN	PTR	myhostname.mydomain.
5	IN	PTR	clienthost1.mydomain.
6	IN	PTR	clienthost2.mydomain.

You might also want to add a zone for the domain you're using, if it doesn't really exist that is..

[sputnik]

Brilliant. Thank you, this is absolutely what i needed.