This problem occurred because was used somewhere to reset iptables, which cleared the Docker network iptables rules. You can confirm this by running the command
This problem occurred because iptables -F was used somewhere to reset iptables, which cleared the Docker network iptables rules.
You can confirm this by running the iptables -t nat -L -n -v command.
To resolve this problem, simply run
This command restarts Docker.
In my case, the iptables -F command was configured to run on a particular kernel, so to use Docker alongside it, I had to restart the Docker service after rebooting.
However, there were also times when iptables -F ran in between reboots,
so I set up a simple script to run to resolve this problem.
/root/check-docker-iptables.sh
#!/bin/bash
# Docker chain이 있는지 확인
if ! iptables -t nat -L DOCKER >/dev/null 2>&1; then
logger "Docker iptables chain missing, restarting Docker service"
systemctl restart docker
else
logger "Docker iptables chains are present"
fi/etc/cron.d/docker-iptables
* * * * * root /root/check-docker-iptables.shThis way, I configured crontab to check iptables and restart Docker if the Docker entries are missing.