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Re: Can't find the DNS Servers




On Wednesday 04 October 2017 14:35:25 David Wright wrote:

> On Wed 04 Oct 2017 at 13:21:02 (-0400), Greg Wooledge wrote:
> > On Wed, Oct 04, 2017 at 11:59:04AM -0500, David Wright wrote:
> > > On Wed 04 Oct 2017 at 09:11:37 (+0300), Reco wrote:
> > > > A correct way to fix this is to "persuade" your DHCP server not
> > > > to provide DNS information.
> > > > Even more correct way is to force your DNS-at-DHCP to use
> > > > 8.8.8.8 as forwarder DNS.
> > > > Since it's unnaturally complex to do so in a consumer-grade
> > > > routers, a hack is in order.
> > >
> > > But won't that send local host lookups to google which won't have
> > > a clue?
> >
> > Which problem are we attempting to solve, exactly?  I seem to recall
> > that the reported symptom was "I can't do apt-get update", which
> > means the priority is getting real Internet DNS resolution working.
>
> "I can't even reach the other computers on my home network if I use
> their names. IP addresses work OK." as well.
>
You probably could if you enter their addresses and names in 
your /etc/hosts file, and you can run the identical /etc/hosts file on 
every machine on your home network. That /etc/hosts file will resemble 
this one:

oot@coyote:~# cat /etc/hosts
127.0.0.1 localhost
192.168.xx.1    router.coyote.den               router
192.168.xx.2    rock64Sheldon.coyote.den        rock64  rock64Sheldon
192.168.xx.3    coyote.coyote.den               coyote
192.168.xx.4    shop.coyote.den                 shop
192.168.xx.5    lathe.coyote.den                lathe
192.168.xx.6    lappy.coyote.den                lappy
192.168.xx.7    sheldon.coyote.den              sheldon
192.168.xx.8    raspberrypi.coyote.den          raspi
192.168.xx.9    odroid64.coyote.den             odroid64
192.168.xx.10   GO704.coyote.den                GO704
192.168.xx.12   picnc.coyote.den                picnc
192.168.xx.21   scanner.coyote.den              scanner
# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Replace the xx.#, the FQDN names and aliases, with yours. And note too 
that you can have more than 1 alias as I show for xx.2 above.

If you have network-mangler installed and running, stop it and remove it 
else you may have to make your /etc/resolv.conf into a normal file, make 
the nameservers work, then chattr +i resolv.conf to keep n-m from 
tearing down a working network.

It should, if your router runs something like dnsmasq, be sufficient to 
point the nameserver entry in your resolv.conf at the router, which 
will, if its internal lookups fail, forward the dns request to your 
ISP's dns servers. That adds about 60 milliseconds to the ping time of 
some site never visited before.


> > If there's a need to add local area network hosts, then *after* the
> > real Internet DNS is working, the OP can decide whether to add LAN
> > hosts to /etc/hosts on each machine, or to set up a LAN DNS
> > nameserver, and wrangle resolv.conf and/or DHCP to point to it. 
> > (Many steps and details omitted here for simplicity's sake.)
>
> I'm obviously out of my league. I was under the impression that
> everyone set up networking by working outwards from the loopback
> interface to the universe, rather than the other way round.

Basically that is how it works.
>
> > Which way the OP *should* go depends mostly on how many LAN hosts
> > we're talking about.  Which way they *will* go... anyone's guess.

Your /etc/hosts file can have, IIRC, up to 253 ipv4 entries. And it still 
is identical on all machines provided they all know their assigned 
names.  Check that by running hostname w/o an argument. See man 
hostname, ditto for domainname.

> As I just posted, I thought the OP was already using a DNS server in
> the Actiontec router. (I don't have that choice.)
>
Why not David? Get one that has enough memory to be reflashed with 
dd-wrt, which will have that feature, and since its .de sourced, not at 
all likely to have any back doors for the 3 letter agencies.

Most routers in the $70+ category can do that. In way over a decade, only 
one person has come thru dd-wrt and I had to give him all the usernames 
and passwd's to do so. I needed his expertise at the time.

Buffalo sells several with dd-wrt already installed, but their branding 
covered up a needed section of the setup, so I had to go get the real 
thing from the dd-wrt site & install it.  Shrug.

> Cheers,
> David.

Cheers David, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>