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Thread: dhclient dns info from ISP not reaching resolvconf

  1. #1
    Join Date
    Apr 2007
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    26

    Unhappy dhclient dns info from ISP not reaching resolvconf

    I have 12.04 on a gateway machine with 2 interfaces and eth0 gets its IP address and the DNS server IP addresses for the whole LAN from the ISP via the ADSL modem.

    I want dhclient from isc-dhcp-client to pass the ISP DNS info to resolvconf to put into the /etc/resolv.conf but this isn't happening.

    I know the DNS IPs are coming in from the modem at DHCP time because I put some debugging into /etc/dhcp/dhclient-enter-hooks.d/resolvconf and I can see them coming through. The IP addresses just never make it into /etc/resolv.conf.

    Up until now, I've been using another machine as the lan's gateway with debian etch and I want to get it running on this new machine with ubuntu.

    I installed the standard ubuntu and it had network-manager installed, so I de-installed that since I'll be using this box with no changes to the network in the long term.

    I've dpkg-reconfigured both isc-dhcp-client and resolvconf but still no joy.

    My guess is that the issue is either a) due to removal of network-manager or (b) a missing line of config somewhere, or (c) something interfering from another package - I have installed dnsmasq for instance (default ubuntu package)

    Have searched up and down the internet and can only find other problems with resolvconf, never this one.

    Any help massively appreciated!

  2. #2
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    75 views so far but no ideas - not a good sign! I was thinking of just re-installing the whole OS - but that's such a Microsoft-style way to go, I can't bring myself to do it.

  3. #3
    Join Date
    Apr 2006
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    417

    Re: dhclient dns info from ISP not reaching resolvconf

    I usually just manually edit resolv.conf on Ubuntu server
    Code:
    nameserver 4.2.2.2
    If you have dnsmasq setup correctly on that machine you can just point it to 127.0.0.1 and get the cached DNS and local DNS you can setup too.

  4. #4
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    yes, thats what i was doing with my old machine. it'd be good to get this new resolvconf program going, but it looks like its foobarred.

  5. #5
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    After googling a bit more just now, I decided to remove and purge dnsmasq and now resolvconf works - the DNS server from my ISP is in there.

    Cool but not that cool - I need dnsmasq. Hmmm. Maybe it will all magically start working when I re-install it. That looks like correct usage of that smilie.

  6. #6
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    Rats. Re-installing dnsmasq just brought back the problem. dnsmasq puts 127.0.0.1 into resolv.conf and chucks out the actual DNS server.

    I guess it's a dnsmasq issue so I'll do some more googling on dnsmasq and start a new thread if I still can't solve it.

  7. #7
    Join Date
    Apr 2006
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    417

    Re: dhclient dns info from ISP not reaching resolvconf

    What are using dnsmasq for? Why do you not want it for DNS? How do you have this option set in dnsmasq.conf?
    # Change this line if you want dns to get its upstream servers from
    # somewhere other that /etc/resolv.conf
    resolv-file=/etc/dnsmasqupstreamservers

  8. #8
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    i need dnsmasq as the dhcp server for my lan. it's the easiest i've come across - although at the moment i'm defaulting to it, haven't looked for a better one recently. maybe i should. or maybe i should de-install resolvconf - don't really need it that bad.

    but i dont understand your question. this is a gateway machine. eth0 is getting its ip address & dns from the ISP.

    dnsmasq serves dhcp to the rest of the lan on eth1 and gives them the gateway machine and I figured it passes on the DNS info from the resolv.conf.

    So why is it overwriting the resolv.conf? I'll look into it but I'm going to post this msg now so i can reconfigure it all and try out that dnsmasq option you mention

  9. #9
    Join Date
    Feb 2009
    Location
    Dallas, TX
    Beans
    7,739
    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: dhclient dns info from ISP not reaching resolvconf

    Hi ahardy66.

    My first guess is that you are using the Desktop Edition.

    12.04 introduced a dnsmasq plugin for Network-Manager. It works great for is intended to do, but it is incompatible with other DNS packages like dnsmasq and bind (read here).

    If you are committed to use the Desktop Edition, you would need to unisntall Network-Manager and manage the network using config files.

    On the other hand, the server edition does not have this problem.

    Let us know how it goes.
    Regards.

  10. #10
    Join Date
    Apr 2007
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    26

    Re: dhclient dns info from ISP not reaching resolvconf

    1 step forward, 2 steps back.

    Now I've got rid of dnsmasq, but still dhclient isn't putting the dns info from the ISP into resolv.conf via resolvconf when the machine brings up eth0

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