Hi, On Wed, Apr 09, 2003 at 12:22:56PM +0200, Bernhard R. Link wrote: > > An example > > =--------- > > /run/resolvers/eth0 Created by the DHCP client process that > > has configured interface eth0. > > "resolv.conf"-formatted info for eth0 > > /run/resolvers/ppp0 Created by the pppd process that has > > created ppp0. > > "resolv.conf"-formatted info for ppp0 > > ... > > /etc/resolvers/default Included in base-files > > Generates /run/resolv.conf which is a > > composite of the above files. The local > > admin can link /etc/resolv.conf to that file > > if s/he doesn't run a local DNS cache. > > Hm, I never worked with anything dynamic like dhcp or ppp or even > several of them. So I wanted to ask why there are entries for > several configurations. (When I remember correct a program resolving > an address has no way to specify an interface for doing so). The advantage is that a system managing a single interface, does not need to 'edit' a shared file; each has a file of its own. That is an aspect of directories that's generally underused IMHO. > I'm also curious, why the parts should be "resolv.conf" formatted. > Nameserver entries can easily be combined, but domain or search > statements seem a bit more tricky. (are they transported by dhcp or > ppp at all?) They are, at least by PPP. > Might a more strict format of theese files (as they > are written/read by programs) useful? It might, but using resolv.conf as the format allows you to implement it trivially by having pppd/dhcp write their existing file to /run/resolvers/<interface> and symlinking /etc/resolv.conf to eg. /run/resolvers/eth0. IOW, it makes implementation smooth and ensures good backwards compatibility. > > /etc/resolvers/named Included in bind package > > Generates /run/bind/named.conf.forwarders > > which is a "forwarders { ... }" statement > > listing all nameserver addresses listed in > > in the files above. Then reloads named. > > The admin can include this file inside the > > "options { ... }" statement in named.conf. > > /etc/resolvers/dnscache Included in djbdns package > > Does appropriate stuff to configure and > > notify dnscache. > > ... > > /sbin/update-resolvers Does a run-parts on /etc/resolvers > > Is called by ifup/ifdown, pon/poff. > > Are multiple "forward-provider" reasonable? Or would an alternative > link be better? I personally think a single update-resolvers script provided by each local cache / resolving library, possibly through the alternatives mechanism is enough; I see little advantage in doing a full blown run-parts. A default version would concatenate (with due care to concatenate 'search' and 'domain' entries into 'search' lists, for sure), the various resolv.confs into a single one to which /etc/resolv.conf could be a symlink. Or, as said, you could initially skip this and just have the admin choose an interface to link his /etc/resolv.conf to. I'd definitely to put the scripts outside /etc/resolvers though; I'd expect them to be fairly static, not conffiles. Cheers, Emile. -- E-Advies - Emile van Bergen emile@e-advies.nl tel. +31 (0)70 3906153 http://www.e-advies.nl
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