Help troubleshooting Pi-hole vps access from inside home network

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1

I have a cheap VPS configured with unbound + pihole + wireguard that I use when I am out & about. I have secured this box with ufw and allow tcp/udp access to port 53 just locally(local interface + fireguard interface). This has worked very well for years now.

I have a pihole instance inside in my home, I would like my router to use my vps as a backup option for dns, but I am having a tough time querying from inside my house to my vps.

This is the netstat output from my vps.

netstat -nltup | grep 'Proto\|:53 '

udp    UNCONN   0        0                 0.0.0.0:53             0.0.0.0:*      users:(("pihole-FTL",pid=3290,fd=4))
udp    UNCONN   0        0               127.0.0.1:5353           0.0.0.0:*      users:(("unbound",pid=930,fd=3))
udp    UNCONN   0        0                    [::]:53                [::]:*      users:(("pihole-FTL",pid=3290,fd=6))
tcp    LISTEN   0        32                0.0.0.0:53             0.0.0.0:*      users:(("pihole-FTL",pid=3290,fd=5))
tcp    LISTEN   0        128             127.0.0.1:5353           0.0.0.0:*      users:(("unbound",pid=930,fd=4))
tcp    LISTEN   0        32                   [::]:53                [::]:*      users:(("pihole-FTL",pid=3290,fd=7))

I have DNSMASQ_LISTENING=all set in the setupVars.conf

I have the following ufw rules.

5353                       ALLOW       127.0.0.1
53                         ALLOW       127.0.0.1
53                         ALLOW       10.10.0.0/24
53/udp                     ALLOW       <home ip>
53/tcp                     ALLOW       <home ip>

I disabled ufw and I still don't see dns working.

I ran tcpdump in the vps and I see my requests coming, but I don't see pihole-FTL getting the request.

tcpdump -i eth0 -s0 port 53
10:24:21.927310 IP <home ip>.50063 > some.domain.org.domain: 11893+ [1au] A? www.nytimes.com. (44)

I have even disabled ufw but I still don't see pihole-FTL(tail -f /var/log/pihole.log) getting the query, does anybody have any thoughts on what other approaches I can debug this issue?

Thanks!
Thadiyan

2

I figured out the issue. It was a confluence of issues. This VPS is running on Ubuntu 18. I am fairly certain I had some iptables mix up, and further throw in ufw in the mix.

I reset the vps and started afresh and everything works as expected now.

I also had an issue with ufw, there is an issue with ufw starting up on a boot up and systemd.