[ale] Multi-label names
Todor Fassl
fassl.tod at gmail.com
Thu Mar 8 09:13:01 EST 2018
But there's only one /etc/resolv.conf file per host. I believe you are
allowed to configure DNS info per interface because it mirrors or
simulates getting DNS info via DHCP. For years you had to manually
create the /etc/resolv.conf file. Then tools like resolvconf came along
and wrote it for you based on the info from DHCP. Since the host was
getting DNS info from DHCP per interface, that info had to be
configurable per interface. I don't know what would happen if you had 2
nics in a machine and configured different DNS info for both. It would
be like having 2 nics, each getting their IP address via DHCP and
getting different DNS configuration too. I don't know how resolvconf
would handle that (speculation below).
But that's not my problem. What has happened is that systemd has created
it's own caching name server, systemd-resolvd, that creates an
interface, 127.0.0.53, for DNS queries and writes an /etc/resolv.conf
pointing there. That caching name server is misbehaving and I can't
figure out how to configure it. I can't even understand the man page.
I can disable systemd-resolvd and manually create my own
/etc/resolv.conf to bypass it. That, of course, still works fine just as
it has since Linus Torvalds wore nickers. But I'd rather not do that.
I'd rather fix systemd-resolvd.
Note 1: I would think Red Hat is going to move to systemd-resolvd
eventually. I'll admit ubuntu if f'ed up. ifupdown, netplan,
network-manager -- plus stuff in systemd. It's a huge mess.
Note 2: It never occured to me before that there was an inherent
conflict in having only one /etc/resolv.conf file per host. What if you
have one nic for example.com and a second for example.net? If you say,
"host spock", does that default to spock.example.com or
spock.example.net? Probably both. And whether it would look for
spock.example.com or spock.example.net first would depend on the order
in which the interfaces were configured. So your /etc/resolv.conf might
look like this:
nameserver 192.168.0.1
search example.com
search example.net
If DHCP also sent different name servers, they would probably both be
listed in there as well. But you can't have different DNS info per
interface because programs like firefox and thunderbird don't talk to an
interface. They talk to the network. Firefox isn't going to want to
decide which interface to talk to when you type in a URL. The list of
name servers and search domains has to be system-wide.
On 03/07/2018 10:11 PM, Jim Kinney via Ale wrote:
> Yeah. Config differences between distros are how people stay with one
> distro over others.
>
> Somewhere, ubuntu has a place to define settings for a network
> interface. If NetworkManager is used, it should pickup stuff like dns,
> default search domain(s), multiple IPs, etc.
>
> I don't poke around with every distro anymore like I used to. Decided it
> was more time efficient to just get frustrated with the changes in one.
>
> :-P
>
> On March 7, 2018 9:36:51 PM EST, DJ-Pfulio via Ale <ale at ale.org> wrote:
>
> I don't have any answers.
>
> First, Ubuntu/debian doesn't use /etc/sysconfig/ anything. That's a
> RHEL-family thing, I think.
>
> Running a non-LTS is crazy, IMHO. In 17.10, network setups changed.
> They've added a new middleman - beyond resolvconf. NetPlan is the name.
> Sorry, I haven't looked at it at all, since no LTS has it.
> https://wiki.ubuntu.com/MigratingToNetplan might be helpful. Someone
> decided that yaml is easier than the interfaces file.
>
> I purge all network manager stuff and either have static IPs or use DHCP
> reservations from the network DHCP server. Find it is easier for my
> needs. I understand that network manager is better now than when it was
> when I had all sorts of issues with it.
>
> I've also found that purging avahi is helpful. It gets in the middle of
> name resolution stuff - I usually see issues with samba that are solved
> by NOT having avahi installed.
>
> But I really don't know anything.
>
> On 03/07/2018 04:40 PM, Jim Kinney via Ale wrote:
>
> I was unclear. I have IP configuration data written in
> /etc/sysconfig/network-scripts/ifcfg-<ifacename> (RHEL/CentOS/Fedora
> location). That's how NetworkManager gets what it needs to run
> networking (as long as it's not blocked in the ifcfg-<device> file
> specifically.
>
> The new method is to have resolve.conf "built" each time the
> network is
> started up.
>
> I use bind managed through Free-IPA for DNS for my domains.
>
> On Wed, 2018-03-07 at 15:01 -0600, Todor Fassl wrote:
>
> You mean add the equivalent values to
> /etc/systemd/resolv.conf? Nothing.
>
> I actually copied a working resolv.conf from another machine to
> /etc/systemd/resolv.conf and restarted systemd.resolvd. The
> resulting
> /etc/resolv.conf file (actually a symlink to
> ../run/systemd/resolve/stub-resolv.conf) was the same. I
> even deleted
> the ../run/systemd/resolve/stub-resolv.conf and then restarted
> systemd.resolvd to make sure it was generating a new file.
> No joy.
>
> I am not totally surprised that experiment did not work
> though. I think
> the resolv.conf is correct as far as it goes. It is the
> behaviour of the
> thing listening at 127.0.0.53 that is in question.
>
>
>
>
>
> On 03/07/2018 01:46 PM, Jim Kinney wrote:
>
> What happens if you add
>
> DNS1=8.8.8.8
> DOMAIN=mydomain.net
>
> To the network configuration? NetworkManager will that
> that as an entry
> in resolv.conf and write it there.
>
> I thought systemd-resolvd was used only (mostly) during
> startup to do
> thing like handle remote filesystems, etc. I've never
> used it.
>
> On March 7, 2018 2:38:13 PM EST, Todor Fassl via Ale
> <ale at ale.org <mailto:ale at ale.org>> wrote:
>
> Well, I could just disable systemd-resolvd and then create a
> /etc/resolv.conf in a text editor. But I'd rather not go
>
> backwards. I've
>
> mentioned before on this list that I rue the day I
> decided to
>
> switch my
>
> end users from debian stable to ubuntu. But I can't go
> back on that
> either. I'd like to get systemd.resolvd working.
>
> Have you ever heard of this term, "multi label name"? I am
>
> thinking it
>
> means either an fqdn *or* an unqualified dn. So examples
> would be
>
> spock
>
> and/or spock.example.com.
>
> On 03/07/2018 12:32 PM, Lightner, Jeffrey wrote:> This
> posts
>
> suggests it
>
> is systemd-resolved and gives options for using dnsmasq
> instead:
>
>
>
>
> https://askubuntu.com/questions/898605/how-to-disable-systemd-resolved-and-resolve-dns-with-dnsmasq
>
>
>
> My RHEL7 systemd doesn't have systemd-resolved.
>
> -----Original Message-----
> From: Ale [mailto:ale-bounces at ale.org] On Behalf Of
> Lightner,
> Jeffrey
>
> via Ale
>
> Sent: Wednesday, March 07, 2018 1:28 PM
> To: Todor Fassl; Atlanta Linux Enthusiasts
> Subject: Re: [ale] Multi-label names
>
> Does it run any better if you turn off systemd-resolv
> (systemctl
> stop
>
> systemd-resolv)?
>
>
> What is in your /etc/resolv.conf on the two servers?
>
>
>
> -----Original Message-----
> From: Ale [mailto:ale-bounces at ale.org] On Behalf Of
> Todor Fassl
> via Ale
> Sent: Wednesday, March 07, 2018 1:09 PM
> To: Atlanta Linux Enthusiasts
> Subject: [ale] Multi-label names
>
> I am having a problem after an upgrade to ubuntu artful.
> If I
>
> do a
>
>
> host lookup for a non-existing, unqualified host name,
> it takes a
>
> long
>
> time to error ot. Say I have a host named spock. I can
> say, "host
>
> spock"
>
> and that comes back instantly. If I say, "host sopck" or
> some other
> typo, it takes like 10 seconds and I get this:
>
> $ host -v sopck
> Trying "sopck.example.com
> Trying "sopck"
> ;; connection timed out; no servers could be reached
>
> On an old machine, I get this:
> $ host -v sopck
> Trying "sopck.example.com
> Trying "sopck"
> Host sopck not found: 3(NXDOMAIN)
> Received 98 bytes from 192.168.0.1#53 in 0 ms
>
> I see that on the ubuntu/artful machines, I am running
> systemd-resolv
>
> (through no fault of my own). It's listening on
> 127.0.0.1 and caching
> DNS queries. So trying to read the man page for
> systemd-resolv, I
>
> keep
>
> coming across the term "multi label names". I never
> heard that term
> before, don't know what it means, and it appears to be
> ungoogleable.
>
>
> Any advice on the original problem or on the meaning of
> that term
>
> would be appreciated.
>
>
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--
Todd
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