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ArnaudParan

Member

Registered: 2021-05-03

Posts: 3

[SOLVED] No internet inside docker

Hello all,

If my post doesnt follow the rules please delete it

I have had issues with docker recently since I installed arch on my new computer, I had no internet connection inside of docker and while
building images. I just wanted to share how I solved it in case anyone (me included) has that issue again. The issue was that docker0
took an ip which was already used by my internet connection (wlan0)

$ ip a yielded

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 44:af:28:1a:32:59 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.42/24 brd 192.168.0.255 scope global dynamic noprefixroute wlan0
       valid_lft 41654sec preferred_lft 36254sec
    inet6 2a01:e0a:4e0:5f0:c17d:b553:57cf:fb5/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 86163sec preferred_lft 86163sec
    inet6 fe80::2419:8b30:35c9:d434/64 scope link 
       valid_lft forever preferred_lft forever
6: br-2ad1dcd37bee: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:7d:f1:50:fa brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global br-2ad1dcd37bee
       valid_lft forever preferred_lft forever
7: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:14:95:89:51 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/16 brd 192.168.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:14ff:fe95:8951/64 scope link 
       valid_lft forever preferred_lft forever

You can see that the ip of wlan0 aka 192.168.0.42/24 and docker0 aka 192.168.0.1/16 do clash, so I solved the issue
by changing the default ip of docker0 by editing /etc/docker/daemon.json with

{
  "default-address-pools":
  [
    {"base":"192.160.0.1/16","size":16}
  ]
}

I restarted docker with systemd and now internet works like a charm