I’m running Raspbian Release 10 (Kernel Linux 5.4.51-v7+) on a RPi Modell 3 with currently two Docker containers. The first container is the “pihole/pihole:latest” image which works just fine. PiHole runs with the IP address 192.168.178.67/24.
pi@myRPi:~ $ cat /etc/resolv.conf
'# Generated by resolvconf
My router has the IP address 192.168.178.1 and works as a backup DNS server. When creating the second container I’m not able to connect to the internet, unless I add ‘–dns 192.168.178.1’ to the command line.
Ping to the backup DNS server
pi@myRPi:~ $ docker container exec e408c3722e1e ping -c 2 192.168.178.1
PING 192.168.178.1 (192.168.178.1) 56(84) bytes of data.
64 bytes from 192.168.178.1: icmp_seq=1 ttl=63 time=2.53 ms
64 bytes from 192.168.178.1: icmp_seq=2 ttl=63 time=4.81 ms
— 192.168.178.1 ping statistics —
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 2.536/3.675/4.814/1.139 ms
Ping to the PiHole
pi@myRPi:~ $ docker container exec e408c3722e1e ping -c 2 192.168.178.67
PING 192.168.178.67 (192.168.178.67) 56(84) bytes of data.
64 bytes from 192.168.178.67: icmp_seq=1 ttl=64 time=0.255 ms
64 bytes from 192.168.178.67: icmp_seq=2 ttl=64 time=0.254 ms
— 192.168.178.67 ping statistics —
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.254/0.254/0.255/0.015 ms
Both DNS servers are reachable from within the second container.
I’d like to use the PiHole instead of the backup DNS server for the second container, but I don’t know why this doesn’t work.
Any help appreciated.