Debian 9 Webmin networking dns server bug

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#1 Thu, 06/06/2019 - 01:25
drguild

Debian 9 Webmin networking dns server bug

Installed Virtualmin / Webmin to my HP 36L Microserver with Debian 9 (new server install)

Just have the basics going but getting a massive bug with 'Hostname and DNS Client' gui page. I am trying to add extra DNS servers so the system can reach outside of the network.

Defaults are: 127.0.0.1 192.168.1.1 192.168.1.254

When trying to add more entries 8.8.8.8 / 8.8.4.4, My ISP DNS servers. Clicking 'Save' then 'Apply Configuration' the whole networking will crash meaning no Webmin, no SSH etc. The system ends up needing a reboot when this happens which when I go back into Webmin 'Hostname and DNS Client' the system is showing the standard DNS's as above.

I don't know if I need the extra entries in there for Debian 9 as Centos 6.5+ I needed to add them. I can ping google with the default entries. in my resolve is this:

domain revnet
search revnet
nameserver 127.0.0.1
nameserver 192.168.1.1
nameserver 192.168.1.254
systemd-resolve --status
Global
         DNS Servers: 127.0.0.1
                      192.168.1.1
                      192.168.1.254
          DNS Domain: revnet
          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

Looking at the Debian wiki help page I see two ways one can add nameservers.

The resolv.conf configuration file The configuration file resolv.conf at /etc/resolv.conf contains information that allows a computer connected to a network to resolve names into addresses. (Note: Do not confuse this configuration file with the program resolvconf, which unfortunately has a nearly identical name.)

The resolv.conf file typically contains the IP addresses of nameservers (DNS name resolvers) that will attempt to translate names into addresses for any node available on the network. There will be a line or lines that look like this:

The resolvconf program If the resolvconf program is installed, you should not edit the resolv.conf configuration file manually as it will be dynamically changed by programs in the system. If you need to manually define the nameservers (as with a static interface), add a line something like the following to the interfaces configuration file at /etc/network/interfaces:

- I assume we are using the resolvconf file and not the program for webmin. Adding entries in resolv.conf manually and restarting the entries are removed. With this bug adding nameservers in the webmin gui crashes the networking interface when applying the configuration.