Arch Linux

Magician21

Member

Registered: 2007-03-23

Posts: 45

DHCP and DNS advice

My home network is being served by a wired Linksys router that provides DHCP (DNS being provided as part of that).

I need to use a static IP address for my Myth master backend.  The problem is that when I do that, I don't have DNS values provided to me by the router.  I know that I could just copy them from the router and put them in /etc/resolv.conf.  However, if those servers change (I have Verizon DSL - going to Fios this week), it's unlikely that I would know about it (unless my master backend stops getting schedule info from SchedulesDirect).

I've already tried just adding the appropriate static IP to my DHCP'd interface (eth0:0).  The problem is that when the DHCP lease expires / renews, the static IP doesn't get re-added.  I was using rc.local to add it at boot time.

I have 3 Linksys WRT54G APs in my house (1 for each floor).  I put White Russian on one, and disabled the DHCP on the wired router.  It turns out that if you specify static DHCP addresses, all the addresses have to be in the static list.  I won't discount that I did something wrong, but also I couldn't find anywhere in the web interface to specify enable / disable (or IP range) for the DHCP server.  It also insisted on specifying itself (192.168.1.12) to clients instead of the value I specified in the web interface (192.168.1.1) for the gateway.

I upgraded to Kamikaze, and didn't even get a web interface out of it.  I eventually restored the Linksys firmware, and I'm back to square one.

I downloaded the GPL firmware for the WRT54G, and am investigating how to simply use dnsmasq to provide DHCP instead of udhcp.  That would get me the static DHCP I need.  I don't see a terribly clear howto for this though, so it's slow going...

Can anyone recommend a solution for me that doesn't involve hard-coding the DNS addresses in my /etc/resolv.conf file?  Bonus points if I don't have to modify firmware.  Double bonus points if I have to modify firmware, and can be walked through it

RedShift

Member

From: Belgium

Registered: 2004-07-16

Posts: 230

Re: DHCP and DNS advice

Why not just use the router's IP address in /etc/resolv.conf? Your DNS server on your router will forward the request or recurse for it on its own.

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Magician21

Member

Registered: 2007-03-23

Posts: 45

Re: DHCP and DNS advice

I tried that too, but forgot to mention it.  It's an older router (BEFSR41), and doesn't seem to do that.  I'm guessing it gets the DNS servers from my ISP, but expects the clients to use them appropriately.

vacant

Member

From: downstairs

Registered: 2004-11-05

Posts: 816

Re: DHCP and DNS advice

Well, if your ISP DNS change during the switch to Fios (or any other time) then you'll know ... because you'll stop getting schedule info. Is that a big problem?

Otherwise set your myth box dns to opendns 208.67.220.220 & 208.67.222.222.

Magician21

Member

Registered: 2007-03-23

Posts: 45

Re: DHCP and DNS advice

Schedule info comes down for 2 weeks at a time, right?  It's unlikely I would notice for approx 2 weeks, until I couldn't record shows.

I hadn't heard of OpenDNS before.  That would be the best solution I can think of.  Thanks!

tam1138

Member

Registered: 2007-09-10

Posts: 238

Re: DHCP and DNS advice

If your router doesn't include one, you could run your own DNS cache.  You could take that a step further and run your own DHCP server, as well, which would allow you to hand out DNS servers of your choice and always give the same IP address to the same machines (effectively static addresses via DHCP).

Magician21

Member

Registered: 2007-03-23

Posts: 45

Re: DHCP and DNS advice

Before I knew about the OpenDNS, I considered that.  Getting the DNS server IP addresses was the part that had me stumped.  dnsmasq was the tool I was looking at, but it really expected to be running on the gateway machine.  Of course, if you hard-code the DNS servers that expectation kind of goes away.

Thanks!