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Thread: Very odd internet connection problem

  1. #21
    Join Date
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    Re: Very odd internet connection problem

    Quote Originally Posted by TheFu View Post

    This is true, but when you've been adding
    nameservers and search to the /etc/resolv.conf file with scripts for 20+ years and it stopped working with 12.04, THAT does suck. It took me some time to find a solution and another day to update AND test the automatic tools which manage these files across our infrastructure. I had better things to do that day. Plus, there isn't any added functionality for servers (static IPs) provided that I can see, besides another level of indirection.
    Even with resolvconf installed you can run with a static file at /etc/resolv.conf, so all you had to do if you wanted to continue using your custom scripts was answer No to the "linkify" question or, after upgrade, delete the symbolic link at /etc/resolv.conf.

    A minor advantage of resolvconf even for a server is that nameserver addresses are associated with the interfaces over which they are accessible, which is clearer.

    The text file method was working just fine for servers. The resolvconf devs should have made that tool backwards compatible
    The package is designed not to break name service on upgrade on machines that have static resolv.conf. I can imagine that machines whose resolv.conf is managed by custom scripts have problems on upgrade. Supporting such machines would have required enhancing glibc so that it could be configured to read another file than /etc/resolv.conf. This would have been a lot of work and would just have made other people unhappy.

    Change for the sake of change seems foolish. I'm just sayin'. </rant> Sorry for that. I do feel better now.
    Changes like that aren't made for no good reason. Prior to resolvconf, all sorts of programs fiddled with /etc/resolv.conf, none of them preserving one another's changes. Resolvconf imposes order on all that.

    I'm not saying that it isn't an improvement for GUI users on DHCP. It definitely seems to be for them.

    It would be extremely helpful if the default /etc/network/interfaces file actually contained an example for static IP configuration - all commented out.
    It does, on a fresh install.

  2. #22
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    Re: Very odd internet connection problem

    Quote Originally Posted by randytuggle View Post
    from interfaces:
    Code:
    # interfaces(5) file used by ifup(8) and ifdown(8)
    auto lo
    iface lo inet loopback
    resolv.conf:
    Code:
    # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
    #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
    nameserver 127.0.1.1
    search hsd1.pa.comcast.net
    That you had "nameserver 127.0.1.1" in /etc/resolv.conf indicates that you were using NetworkManager and its forwarding nameserver dnsmasq. Dnsmasq has known bugs.

    https://bugs.launchpad.net/ubuntu/+s...q/+bug/1003842

    Best to disable it. Comment out "dns=dnsmasq" in /etc/NetworkManager/NetworkManager.conf and then reboot.

    Quote Originally Posted by randytuggle View Post
    resolv.conf shows 8.8.8.8 and when I ping it, it works fine. I'm using wired ethernet without any wi-fi, too. I tried the network reboot method you suggested, and nothing helps. This is really odd.
    You later set your nameserver address to 8.8.8.8. The correct way to do this when you are using resolvconf and NetworkManager is to open the Connection Editor and set Method to "Automatic (DHCP) addresses only" and add the desired address (in this case, 8.8.8.8) to the "Additional DNS servers" field.

    If you are using ifup to configure the interface in question rather than NetworkManager then you put a "dns-nameservers" option in /etc/network/interfaces as has been mentioned earlier.

    Either way, make sure that /etc/resolv.conf is a symbolic link pointing to ../run/resolvconf/resolv.conf. Unless you've decided to run with a static resolv.conf file, that is.
    Last edited by jdthood; January 15th, 2013 at 06:52 PM.

  3. #23
    Join Date
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    Re: Very odd internet connection problem

    Quote Originally Posted by jdthood View Post
    It does, on a fresh install.
    Thank you very much for the detailed response. My network needs have always been fairly simple with no more than 4 interfaces involved and stacked DNS providers, so having a different provider for a different interface never occurred to me. THAT is slick!

    Please keep fighting the good fight to make it better for idiots like myself even when we seem unappreciative!

  4. #24
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    Re: Very odd internet connection problem

    Quote Originally Posted by TheFu View Post
    [B]having a different provider for a different interface never occurred to me. THAT is slick!
    It sounds as if you may have misinterpreted what I said. Resolvconf can't cause the glibc resolver to use different nameservers for different network interfaces. The glibc resolver always uses the same nameserver list for all interfaces. What resolvconf does is: it allows, for each interface, nameserver address information to be included with other information relevant to that interface (gateway address, etc.)

    Whereas the glibc resolver can't select a different nameserver per interface, the dnsmasq forwarding nameserver can select an upstream nameserver depending on the domain to be looked up. This is the most important feature for the sake of which dnsmasq (controlled by NetworkManager) was introduced to the default Desktop installation in 12.04.

  5. #25
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    Re: Very odd internet connection problem

    Quote Originally Posted by jdthood View Post
    It sounds as if you may have misinterpreted what I said. Resolvconf can't cause the glibc resolver to use different nameservers for different network interfaces. The glibc resolver always uses the same nameserver list for all interfaces. What resolvconf does is: it allows, for each interface, nameserver address information to be included with other information relevant to that interface (gateway address, etc.)

    Whereas the glibc resolver can't select a different nameserver per interface, the dnsmasq forwarding nameserver can select an upstream nameserver depending on the domain to be looked up. This is the most important feature for the sake of which dnsmasq (controlled by NetworkManager) was introduced to the default Desktop installation in 12.04.
    I must still misunderstand 'cause DNS works by letting different nameservers respond to different domains as the authoritative answer, otherwise we'd all have local hosts files like in the beginning.

    Well, we should probably not take over this thread and I should probably read up on resolveconf more before asking anymore questions. Thanks for trying.

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