Arch Linux

merasil

Member

Registered: 2019-06-08

Posts: 1

Problem with dns and local name resolution

Hi there,

i currently trying to solve a problem within a heterogeneous network (linux servers with arch, windows clients).

Current Situation:
I got a nat gateway which runs dnsmasq as dns and dhcp server. It got 3 interfaces (wan, home, guest) with different networks. Interfaces got static ips via systemd-networkd. The files are located at /etc/systemd/network/eth*.network:

eth0 (wan):

[Match]
Name=eth0

[Network]
Address=192.168.0.4/24
Gateway=192.168.0.254
DNS=192.168.0.254

eth1(guest):

[Match]
Name=eth1

[Network]
Address=172.17.0.254/16

eth2(home):

[Match]
Name=eth2

[Network]
Address=172.16.0.254/16

nsswitch.conf looks like that:

# Name Service Switch configuration file.
# See nsswitch.conf(5) for details.

passwd: files mymachines systemd
group: files mymachines systemd
shadow: files

publickey: files

hosts: files mymachines myhostname resolve [!UNAVAIL=return] dns
networks: files

protocols: files
services: files
ethers: files
rpc: files

netgroup: files

dnsmasq is setup this way:

domain-needed
bogus-priv
no-resolv
dhcp-sequential-ip

interface=lo
interface=eth1
interface=eth2
bind-interfaces

domain=local
expand-hosts
local=/local/

server=192.168.0.254
#server=8.8.8.8
#server=8.8.4.4

dhcp-range=eth1,172.17.2.1,172.17.2.200,255.255.0.0,168h
dhcp-range=eth2,172.16.2.1,172.16.2.200,255.255.0.0,168h
dhcp-option=eth1,3,172.17.0.254
dhcp-option=eth2,3,172.16.0.254
dhcp-option=eth1,6,172.17.0.254
dhcp-option=eth2,6,172.16.0.254

Behind the nat gateway there is another router (192.168.0.254) which provides DNS-Services. I got another Linux-Server on 172.16.0.1 (server01).
I configured the /etc/hosts on the nat gateway like this:

# Static table lookup for hostnames.
# See hosts(5) for details.
127.0.0.1       localhost
172.16.0.254     server02
172.17.0.254     server02
192.168.0.4       server02
172.16.0.1     server01

There is nothing written in /etc/resolv.conf on nat gateway. I can ping www.google.de or similiar from every device within my network and it resolves fine. if i use drill with any hostname (no matter if they are looking for local hosts or in the internet) on my linux machines i get this error:

Error: error sending query: No (valid) nameservers defined in the resolver

if i use nslookup on my linux machines they time out (no matter if its looked for local hosts or in the internet). pinging www.google works. pinging for server02 (or server02.local, .lan or whatever) on server01 isnt. I am using systemd-resolved as my dns-service on server01. Interface config for server01 is this:

[Match]
Name=eth0

[Network]
Address=172.16.0.1/16
Gateway=172.16.0.254
DNS=172.16.0.254

resolvectl status on server01:

Global
       LLMNR setting: yes
MulticastDNS setting: yes
  DNSOverTLS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes
Fallback DNS Servers: 1.1.1.1
                      9.9.9.10
                      8.8.8.8
                      2606:4700:4700::1111
                      2620:fe::10
                      2001:4860:4860::8888
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home
                      internal
                      intranet
                      lan
                      local
                      private
                      test

Link 2 (eth0)
      Current Scopes: DNS LLMNR/IPv4
DefaultRoute setting: yes
       LLMNR setting: yes
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: allow-downgrade
    DNSSEC supported: yes
  Current DNS Server: 172.16.0.254
         DNS Servers: 172.16.0.254

If i use nslookup on my windows machines i get a resolution for any hostname (server01, server01.local, etc) (no matter if they are local or in the internet). if i ping for server02 it cant resolve. if i ping for server02.local or server01.local it resolves.
I really cant explain this behavior. My best guess is that it has something todo with another dns server that is running somewhere hidden in my network. But this must be a client or whatever, since there are only two servers with very minimal setup. i have looked for avahi-daemons running anywhere but i dont find any or i am doing it the wrong way.
Can some1 give me a hint where to look at to solve my problems? My biggest problem is that i want to access my samba shares at server01 via hostname resolution, which doesnt work

Last edited by merasil (2019-06-08 12:05:06)