[Dnsmasq-discuss] [Feature Request?] Per-Domain resolv.conf

Aaron D. Brooks aaron.brooks at sicortex.com
Wed Sep 26 03:26:13 BST 2007


    You might be interested in looking at the solution used in Gentoo
for what is an inherent problem with a multi-homed system with dynamic

    Gentoo uses their own net-dns/resolvconf-gentoo which hooks into
the init scripts (and dhcp clients) of each interface so that it can
be notified when an interface's configuration changes. resolvconf
stitches the resolution information for each interface into one
resolv.conf file which can be use directly as /etc/resolv.conf.

    resolveconf has further specific support for dnsmasq which
generates an /etc/dnsmasq-resolv.conf file which you point dnsmasq to,
allowing your system /etc/resolv.conf to point to localhost (dnsmasq).

    Because of the nature of hooking into the init/rc scripts,
resolvconf is very specific to Gentoo at this time but maybe it's
worth a look to make something which is more amenable to a Debian


Aaron Brooks - Senior Software Engineer
http://SiCortex.com - Teraflops from Miliwatts

On Tue, Sep 25, 2007 at 05:39:03PM -0500, Thomas Stephens wrote:
> Hello. I am using dnsmasq locally on my computer to solve a split-dns
> problem with the vpnc VPN client. I've got it working, but it's very
> hackish. The setup is:
> When I log into my company's VPN, I need to be able to resolve company
> hostnames. This is done by querying the DNS servers which are sent to
> vpnc. The problem is, they only resolve internal names. Normally,
> using resolvconf, vpnc will concatenate my external and internal
> nameservers. However, since they are all "up" the first one queried
> will respond, but will respond with host-not-found if it's the public
> DNS and an internal name, or vice-versa.
> I got around the problem by adding a server= line to dnsmasq.conf for
> each of the nameservers. For the public nameserver, I did not specify
> a domain, but for the VPN name servers, I had to specify the domain as
> mycompany.com.
> This mostly works, but there are some problems:
> 1) If my company decides to change DNS server IP addresses, I've gotta
> change the dnsmasq config file.
> 2) When I'm not logged into VPN, all accesses to my company's domain
> (i.e. www.mycompany.com) fail, even if they are accessible outside the
> VPN.
> 3) corollary: I have to manually specify the address of the vpn
> connection gateway with an address directive. If this IP changes I
> must, again, change the dnsmasq.conf file.
> The solution I'd like to implement is this: point dnsmasq at a
> resolv.conf for the default nameserver, as well as a resolv.conf for
> the VPN. When I connect with vpnc, the vpn-resolv.conf gets written,
> and when I disconnect it gets deleted or cleared (this part I've
> already implemented).
> I would then tell dnsmasq that the vpn-resolv.conf file is only to be
> used for mycompany.com domain names (either with syntax like
> resolv-file=/mycompany.com/vpn-resolv.conf or by having dnsmasq read
> the domain field of the resolv.conf file). This way, when the
> vpn-resolv.conf file is filled in (I'm connected to the VPN), internal
> names get resolved. When I'm not connected, all requests go to the
> default DNS.
> If this is already possible through some other mechanism, please let
> me know. I'm using dnsmasq 2.40 in Debian unstable.
> Thanks,
> Thomas
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