Getting PPP to set the forwarders for named

sgmeunier · 11-22-2006, 04:13 AM

I've set up a caching nameserver on my SuSE 10.1 box using BIND 9.3.2. Yast has an option where the PPP daemon can automatically update the forwarders for named. I'd like to know how this is done behind the scenes in the config files and how one goes about setting this manually, i.e. without the use of Yast. Also, is there any way to check which forwarders a running named process is using so that I can test it?

gilead · 11-22-2006, 09:33 PM

The DNS forwarders are usually set in /etc/named.conf in the options section. I'm not sure whether yast does something different but you can manually configure forwarders with something like this

Code:

options {
  directory "/var/named";
  forward first;
  forwarders {
    203.0.xxx.xxx;
  };
  query-source address * port 53;
  listen-on {
    127.0.0.1;
    };
  listen-on {
    192.168.1.10;
    };
};

sgmeunier · 11-23-2006, 12:13 AM

Thanks for the reply. I'm aware of the forwarders line in named.conf but I need the forwarders to change depending on what isp I'm using - I use a dial-up and gprs and both are through different isps. I could write a script to do it for me, but before I go that route I wondered if there was a simpler solution because of the "Let the PPP daemon set the forwarders" option in Yast. But I'm unable to discern what exactly this option does in terms of configuration files.

I did find some info on the net regarding a "named.boot" that had a forwarders line in it. I already wrote a script that sets the forwarders in that file automatically based on the nameserver entries in /etc/ppp/resolv.conf when I connect, but I'm under the impression that BIND 9 no longer uses named.boot. It's a pity that there isn't something like postfix's postconf which allows you to easily change entries in postfix's configuration through a script.

gilead · 11-23-2006, 05:04 AM

I'd expect the "Let the PPP daemon set the forwarders" option in Yast does something with sed -i to named.conf. You're correct in that named.boot was used by older versions of BIND.

When I used dial up access I used a script that modified my DNS set up as part of the connection process - it worked fine, there just needs to be a corresponding script that restores the settings on disconnect.

Sorry that wasn't particularly helpful...

sgmeunier · 11-23-2006, 05:32 AM

I guess the bottom line is that I'll have to write a script to do it for me. Although, this morning I found that my isp's nameserver couldn't resolve an address that I was trying to connect to. I thought the problem was with my set-up but even when I did a "dig @<isp's nameserver>" it couldn't resolve it. When I disabled the forwarders and let my caching nameserver resolve it I had no problem. So I'm tempted to disable forwarders, although I haven't run it long enough yet to compare the pros and cons of it.

Thanks for your help.