Script to fix Docker iptables on Synology NAS

old-docker-iptables-fix.sh

#!/bin/bash

start() {
  iptables -t nat -N DOCKER
  iptables -t nat -A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
  iptables -t nat -A PREROUTING -m addrtype --dst-type LOCAL ! --dst 127.0.0.0/8 -j DOCKER
}

stop() {
  iptables -t nat -D PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
  iptables -t nat -D PREROUTING -m addrtype --dst-type LOCAL ! --dst 127.0.0.0/8 -j DOCKER
}

status() {
  iptables -t nat -L PREROUTING
}

case "$1" in 
  start)
    start
    ;;
  stop)
    stop
    ;;
  restart)
    stop
    start
    ;;
  status)
    status
    ;;
  *)
    echo "Usage: $0 {start|stop|status|restart}"
esac

exit 0

First, SSH into your Synology, then use sudo su - to enter sudo mode.

Finally, run the following commands to download the script and set the appropriate permissions:

curl https://gist.githubusercontent.com/PedroLamas/47e49d44ea885947a3fce69166238f2f/raw/docker-iptables-fix.sh -o /usr/local/etc/rc.d/docker-iptables-fix.sh
chmod 755 /usr/local/etc/rc.d/docker-iptables-fix.sh