Docker: How to re-create dockers additional iptables rules?
If you're running Ubuntu on the host, you can use the iptables-save utility to save the iptables rules to a file after you start the docker daemon. Then, once you flush the old rules, you can simply restore the original docker rules using iptables-restore & the saved rules file.
If you don't want to restore all the old iptables rules, you can alter the saved rules file to keep only the ones you need.
If you're running another operating system, you might find a similar alternative.
the best way is to restart your docker service, then it'll re-add your docker rules to iptables. (on deb-based: sudo service docker restart)
however, if you just want to restore those rules without restarting your service, i saved mine so you can inspect, and adjust it to work for you, then load using sudo iptables-restore ./iptables-docker-ports.backup
edit and save this to ./iptables-docker-ports.backup
# Generated by iptables-save v1.4.21 on Thu Apr 30 20:48:42 2015
*nat
:PREROUTING ACCEPT [18:1080]
:INPUT ACCEPT [18:1080]
:OUTPUT ACCEPT [22:1550]
:POSTROUTING ACCEPT [22:1550]
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.17.0.1/32 -d 172.17.0.1/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 3001 -j DNAT --to-destination 172.17.0.1:80
COMMIT
# Completed on Thu Apr 30 20:48:42 2015
# Generated by iptables-save v1.4.21 on Thu Apr 30 20:48:42 2015
*filter
:INPUT ACCEPT [495:53218]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [480:89217]
:DOCKER - [0:0]
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A DOCKER -d 172.17.0.1/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 80 -j ACCEPT
COMMIT
# Completed on Thu Apr 30 20:48:42 2015