Re: Does a home network router need to run a DNS server for robust name resolution ?
- From: Joe <joe@xxxxxxxxxxxxxx>
- Date: Sun, 23 Apr 2006 21:10:50 +0100
Geico Caveman wrote:
Hello
I am setting up a home network with a gateway machine that acts as a
firewall and NAT forwarding host. I have set up a DHCP server and a DHCP
client on this machine. The client talks to eth0, which is the connection
to the cable modem. The server listens on wlan0, which is a wireless
network device (Netgear MA311) running hostap drivers as an access point.
The DHCP server works - wireless clients are able to connect and get IP
addresses. On the router, I am running guarddog and guidedog to make
firewalling and IP masquerade easier.
My /etc/dhcp3/dhcpd.conf :
ddns-update-style interim;
ignore client-updates;
option domain-name "domain.edu";
option domain-name-servers 192.168.1.1;
option routers 192.168.1.1;
default-lease-time 28800;
max-lease-time 86400;
authoritative;
log-facility local7;
subnet 192.168.1.0 netmask 255.255.255.0
{
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
range 192.168.1.3 192.168.1.5;
}
host host2
{
hardware ethernet xx:xx:xx:xx:xx:xx;
fixed-address 192.168.1.2;
}
From client host2 above, I can ssh into any server on the Internet as long
as I use its IP address. However, when I use the FQDN, I get a temporary
failure of name resolution. This means that while my wireless clients can
get through to the Internet, the router does not resolve names for them.
As an experiment, I then placed an internet (non class C address) nameserver
from the router's /etc/resolv.conf (generated by its dhcp client from the
ISP's response) into the option domain-name-servers line, restarted the
DHCP server, got another lease on the client, and name resolution on the
clients worked perfectly. However, this is a fragile solution - the day my
ISP changes its name servers, my clients will stop getting name resolution
again.
Do I need to set up a DNS server like bind on the router for name resolution
to occur or can the DHCP server be tweaked to forward all name resolution
requests to its own nameserver on the Internet in a robust fashion
(something that makes the option domain-name-servers line dynamic,
dependent on the current contents of its /etc/resolv.conf, for instance) ?
If so, can you point me to a resource that explains this ?
GC
It is recommended that you run a local DNS server. While the ISP should
not often change DNS servers, it may happen. There are alternatives to
bind, which is probably more than you need, though it will certainly do
the job.
You seem not to be using a named distribution for the router, in which
case the easiest caching DNS server to install is probably djbdns
( http://cr.yp.to/djbdns.html ) which uses simpler configuration files
than bind. I've used it before, though I'm currently using bind which
is trivial to install on Debian.
The wireless device may itself have a simple DNS server, but I'm a bit
wary of them. A Speedtouch DNS server caused me considerable difficulty
until I realised it wasn't handling certain types of request.
.
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