sysadmin stuff by @jeekajoo ABOUT Archives <p class="navbar-text pull-right">Logged in as <a href="#">username</a></p> /.nav-collapse Docker and IPtables TL;DR; By default, docker daemon appends iptables rules for forwarding. For this, it uses a filter chain named DOCKER . Chain FORWARD ( policy DROP ) target prot opt source destination DOCKER all -- 0.0 . 0.0 / 0 0.0 . 0.0 / 0 ... Chain DOCKER ( 1 references ) target prot opt source destination Moreover, when you tell docker to expose a port of a container, it exposes it to the entire world, breaking your possibly existing iptables rules. So.. if you are running docker on a host that already have an iptables based firewall, you should probably set --iptables=false . Let's take an example. You want to start nginx and bind containerPort 80 to hostPort 9090 : docker run --name so...