Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.debian.user > #270924

Re: NetworkManager with dnsmasq caching NXDOMAIN response of router

From jeremy ardley <jeremy.ardley@gmail.com>
Newsgroups linux.debian.user
Subject Re: NetworkManager with dnsmasq caching NXDOMAIN response of router
Date 2024-07-08 05:50 +0200
Message-ID <IXNy2-Bez-3@gated-at.bofh.it> (permalink)
References <IXJkJ-yNn-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw


On 8/7/24 07:03, David Ayers wrote:
> Hello everyone!
> 
> My Debian 12/bookworm laptop uses DHCP with NetworkManager which
> produce an /etc/resolv.conf containing:
> # Generated by NetworkManager
> ```
> search home
> nameserver 192.168.1.254
> ```
> 
> I've setup NetworkManager to use its local dnsmasq instance to add
> additional name resolution for libvirt and a VPN, according to [1].
> My /etc/NetworkManager/conf.d/localdns.conf contains:
> ```
> [main]
> dns=dnsmasq
> ```
> and my /etc/NetworkManager/dnsmasq.d/local_dnsmasq.conf contains
> ```
> server=/virt/192.168.122.1
> server=/122.168.192.in-addr.arpa/192.168.122.1
> server=/vpn/10.70.71.1
> server=/71.70.10.in-addr.arpa/10.70.71.1
> log-queries
> ```
> 
> The name resolutions (and reverse resolutions) for the the *.vpn and
> *.virt work just fine.  But I'm having issues with the *.home domain as
> soon as set the dns=dnsmasq in /etc/NetworkManager/conf.d/localdns.conf
> independent of any entries in
> /etc/NetworkManager/dnsmasq.d/local_dnsmasq.conf
> 
> After starting (or restarting) NetworkManager either with
> ```
> sudo systemctl reload NetworkManager.service
> ```
> or with
> ```
> sudo nmcli general reload dns-full
> ```
> the name resolution works twice for anyhost.home in the local domain
> but subsequently fails with NXDOMAIN.
> 
> Here ist the output of the log-queries output for a successful
> ```
> ping -c 1 nas-server.home
> PING nas-server.home (192.168.1.103) 56(84) bytes of data.
> 64 bytes from nas-server.home (192.168.1.103): icmp_seq=1 ttl=64 time=7.47 ms
> ```
> with the corresponding
> ```
> sudo tail -f /var/log/syslog
> TS HOST systemd[1]: Reloaded NetworkManager.service - Network Manager.
> TS HOST dnsmasq[169260]: query[A] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[169260]: forwarded nas-server.home to 192.168.1.254
> TS HOST dnsmasq[169260]: query[AAAA] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[169260]: forwarded nas-server.home to 192.168.1.254
> TS HOST dnsmasq[169260]: reply nas-server.home is 192.168.1.103
> TS HOST dnsmasq[169260]: reply nas-server.home is NXDOMAIN
> TS HOST dnsmasq[169260]: query[PTR] 103.1.168.192.in-addr.arpa from 127.0.0.1
> TS HOST dnsmasq[169260]: forwarded 103.1.168.192.in-addr.arpa to 192.168.1.254
> TS HOST dnsmasq[169260]: reply 192.168.1.103 is nas-server.home
> ```
> Notice the IPv6 AAAA query and the two replies with the FQDN.
> 
> The first subsequent query succeeds again with:
> ```
> ping -c 1 nas-server.home
> ping: nas-server.home: Name or service not known
> ```
> with the corresponding
> ```
> sudo tail -f /var/log/syslog
> TS HOST dnsmasq[171213]: query[A] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server.home is NXDOMAIN
> TS HOST dnsmasq[171213]: query[AAAA] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server.home is NXDOMAIN
> TS HOST dnsmasq[171213]: query[A] nas-server from 127.0.0.1
> TS HOST dnsmasq[171213]: forwarded nas-server to 192.168.1.254
> TS HOST dnsmasq[171213]: query[AAAA] nas-server from 127.0.0.1
> TS HOST dnsmasq[171213]: forwarded nas-server to 192.168.1.254
> TS HOST dnsmasq[171213]: reply nas-server is 192.168.1.103
> TS HOST dnsmasq[171213]: reply nas-server is NXDOMAIN
> TS HOST dnsmasq[171213]: query[PTR] 103.1.168.192.in-addr.arpa from 127.0.0.1
> TS HOST dnsmasq[171213]: forwarded 103.1.168.192.in-addr.arpa to 192.168.1.254
> TS HOST dnsmasq[171213]: reply 192.168.1.103 is nas-server.home
> ```
> Notice that the FQDN caches with NXDOMAIN are followed up with just the
> host name and the same two replies, one with the IP and the other with
> NXDOMAIN.
> 
> But all subsequent queries will fail with:
> ```
> ping -c 1 nas-server.home
> ping: nas-server.home: Name or service not known
> ```
> with the corresponding
> ```
> TS HOST dnsmasq[171213]: query[A] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server.home is NXDOMAIN
> TS HOST dnsmasq[171213]: query[AAAA] nas-server.home from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server.home is NXDOMAIN
> TS HOST dnsmasq[171213]: query[A] nas-server from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server is NXDOMAIN
> TS HOST dnsmasq[171213]: query[AAAA] nas-server from 127.0.0.1
> TS HOST dnsmasq[171213]: cached nas-server is NXDOMAIN
> ```
> 
> Once I restart/reload NetworkManager (i.e. clear the cache) I get two
> successful name resolutions with subsequent requests failing again.
> 
> I do notice that when querying external domains, they seem to return
> NODATA-IPv6 instead of NXDOMAIN for what I assume are the AAAA queries.
> But I have no control of that my ZTE based ISP suppired router will
> reply for the AAAA queries.  I suppose, that the router is returning
> the wrong reply for its own local domain for AAAA queries.
> 
> So I guess my question is, can I tell dnsmasq somehow not to cache
> NXDOMAIN or interpret it as NODATA-IPv6 for queries to the *.home
> domain?
> 
> Any other suggestions are also welcome!
> 
> And in case this isn't it, where is the correct mailing list, to pose
> suche a question?
> 
> Thanks, anyone!
> David
> 
> [1] https://networkmanager.dev/docs/api/latest/NetworkManager.conf.html

There is also the file /etc/nsswitch.conf. That gives you fine grained 
control over name services and the order they are consulted

If you have a very small .home network you can create static entries in 
/etc/hosts and if configured in nsswitch.conf will be used before any 
call to an external dns provider.

Back to linux.debian.user | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

NetworkManager with dnsmasq caching NXDOMAIN response of router David Ayers <ayers@fsfe.org> - 2024-07-08 01:20 +0200
  Re: NetworkManager with dnsmasq caching NXDOMAIN response of router jeremy ardley <jeremy.ardley@gmail.com> - 2024-07-08 06:10 +0200
    Re: NetworkManager with dnsmasq caching NXDOMAIN response of router David Ayers <ayers@fsfe.org> - 2024-07-08 12:00 +0200
      Re: NetworkManager with dnsmasq caching NXDOMAIN response of router Detlef Vollmann <dv@vollmann.ch> - 2024-07-10 15:20 +0200
        Re: NetworkManager with dnsmasq caching NXDOMAIN response of router Greg Wooledge <greg@wooledge.org> - 2024-07-10 15:20 +0200
          Re: NetworkManager with dnsmasq caching NXDOMAIN response of router songbird <songbird@anthive.com> - 2024-07-11 01:00 +0200
  Re: NetworkManager with dnsmasq caching NXDOMAIN response of router jeremy ardley <jeremy.ardley@gmail.com> - 2024-07-08 05:50 +0200
  Re: NetworkManager with dnsmasq caching NXDOMAIN response of router Michael Kjörling <c9bc136c6063@ewoof.net> - 2024-07-08 09:50 +0200

csiph-web