docker container not accepting traffic from another container

[dsl400]

Maintainer: @G-M0N3Y-2503
Environment: x86/64 OpenWrt 22.03.0 r19685-512e76967f / LuCI openwrt-22.03 branch git-22.245.77528-487e58a

root@OpenWrt:~# dockerd --version
Docker version 20.10.18, build e42327a
root@OpenWrt:~# docker --version
Docker version 20.10.18, build b40c2f6
root@OpenWrt:~# 

Description:

BusyBox v1.35.0 (2022-09-03 02:55:34 UTC) built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt 22.03.0, r19685-512e76967f
 -----------------------------------------------------
root@OpenWrt:~# docker run --rm -itd --network testnetwork --name test1 busybox
root@OpenWrt:~# docker run --rm -itd --network testnetwork --name test2 busybox
root@OpenWrt:~# docker exec -it test1 sh
/ # ping test2
PING test2 (172.18.0.3): 56 data bytes
--- test2 ping statistics ---
5 packets transmitted, 0 packets received, 100% packet loss
/ # 

[G-M0N3Y-2503]

Unfortunatly, if you are using firewall4/nftables, docker doesn't work as easily as it did with firewall3/iptables.
That is to say, If you are using firewall4, i'd imagine that if you disabled the iptables option in /etc/config/dockerd you should be able to configure the firewall and NAT etc within OpenWrt itself.

[michaellmonaghan]

This is still an issue as of 23.05.0-rc2.

[G-M0N3Y-2503]

OpenWrt: #16818 (comment)
Docker: moby/moby#26824

[G-M0N3Y-2503]

#17766