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Most of the info I see online says to edit /etc/resolv.conf, but any changes I make just get overridden.

$ cat /etc/resolv.conf 
# 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

It seems that 127.0.1.1 is a local instance of dnsmasq. The dnsmasq docs say to edit /etc/resolv.conf. I tried putting custom nameservers in /etc/resolv.conf.d/base, but the changes didn't show up in /etc/resolv.conf after running sudo resolvconf -u.

FYI, I don't want to change DNS on a per-connection basis, I want to set default DNS settings to use for all connections when not otherwise specified.

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5 Answers 5

I believe if you want to override the DNS nameserver you merely add a line similar to this in your base file under resolv.conf.d.

Example

$ sudo vim /etc/resolvconf/resolv.conf.d/base

Then put your nameserver list in like so:

nameserver 8.8.8.8
nameserver 8.8.4.4

Finally update resolvconf:

$ sudo resolvconf -u

If you take a look at the man page for resolvconf it describes the various files under /etc/resolvconf/resolv.conf.d/.

   /etc/resolvconf/resolv.conf.d/base
          File  containing  basic  resolver  information.  The lines in this 
          file are included in the resolver configuration file even when no
          interfaces are configured.

   /etc/resolvconf/resolv.conf.d/head
          File to be prepended to the dynamically generated resolver 
          configuration file.  Normally this is just a comment line.

   /etc/resolvconf/resolv.conf.d/tail
          File to be appended to the dynamically generated resolver 
          configuration file.  To append nothing, make this  an  empty  
          file.   This file is a good place to put a resolver options line 
          if one is needed, e.g.,

              options inet6

Even though there's a warning at the top of the head file:

$ cat /etc/resolvconf/resolv.conf.d/head
# 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

this warning is is there so that when these files are constructed, the warning will ultimately work its way into the resulting resolv.conf file that these files will be used to make. So you could just as easily of added the nameserver lines that are described above for the base file, to the head file too.

References

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I believe you should add this line to the base file as the head file basically contains the header comments to tell you not to modify the file. –  xuhdev May 29 at 6:18
    
@xuhdev - I've changed the A to use base but you could've used head as well. See my updates for more info. –  slm May 29 at 6:34

I am also interested in this question and I tried the solution proposed @sim.

To test it, I put

nameserver 8.8.8.8

in /etc/resolvconf/resolv.conf.d/base and

nameserver 8.8.4.4

in /etc/resolvconf/resolv.conf.d/head

Then I restarted the network with

sudo service network-manager restart

The result is that /etc/resolv.conf looks like

# 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 8.8.4.4
nameserver 127.0.1.1

and nm-tool states that the dnsserver are

DNS:             208.67.222.222
DNS:             208.67.220.220

which are the ones provided by my router. On the other hand digging an address tells that

;; Query time: 28 msec
;; SERVER: 8.8.4.4#53(8.8.4.4)

If I am right, I conclude from all this that

  1. only the "head" part is read by resolvonf: the "base" part is somehow controlled by dnsmasq
  2. the dnsserver is actually forced to 8.8.4.4 regardless of the server provided by dhcp, BUT you loose the caching provided by dnsmasq, since the request is always sent to 8.8.4.4
  3. dnsmasq is still using ONLY the dnsserver provided by dhcp.

All in all, it works but I don't think it is the intended result asked for. A more close solution I think is the following. Edit

sudo vim /etc/dhcp/dhclient.conf

then add

supersede domain-name-servers 8.8.8.8;

The result is the following: resolv.conf contains only 127.0.0.1, which means that dnsmasq cache is invoked and nm-tool says

DNS:             8.8.8.8

which means that if the name searched for is not in the cache, then it is asked for at 8.8.8.8 and not at the server provided by dhcp.

Another (perhaps better) option is to use "prepend" instead of "supersede": in this way, if the name is not resolved by 8.8.8.8, then the request falls back on the other server. In fact, nm-tool says

DNS:             8.8.8.8    
DNS:             208.67.222.222
DNS:             208.67.220.220
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A quick and dirty workaround that wasn't mentioned yet is setting the immutable flag on the resolv.conf file right after editing it.

$ sudo nano /etc/resolv.conf

Add this and save:

nameserver 8.8.8.8

Then:

$ sudo chattr +i /etc/resolv.conf

That should do the trick. I do this on my system too.

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Try adding dns-nameservers XXX.XXX.XXX.X into your /etc/networking/interfaces file.

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Leave a comment when you downvote, please. This is the method given in the manual, page 38. –  Zook Jul 24 at 16:07

sudo echo -e "nameserver 8.8.8.8\n" | sudo resolvconf -a eth0

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2  
Hi and welcome to the site We like answers to explain what they do and how they work here. Please don't post one-line code only answers. Also, there's no point in using sudo for the echo, you only need it for the resolvconf. Similarly, there is absolutely no point in using -e and \n. Simple echo adds a newline anyway, what you're doing will print an empty line. If that's what you wanted, then please explain why. –  terdon Aug 11 at 11:05

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