Usernet Portmap Natunprot

Container on a nat-unprotected network, with a published port

Running the daemon with the userland proxy disable then, as before, adding a network running a container with a mapped port, equivalent to:

docker network create \
  -o com.docker.network.bridge.name=bridge1 \
  -o com.docker.network.bridge.gateway_mode_ipv4=nat-unprotected \
  --subnet 192.0.2.0/24 --gateway 192.0.2.1 bridge1
docker run --network bridge1 -p 8080:80 --name c1 busybox

Most rules are the same as the nat mode network:

{{index . "Ruleset4"}}

But ...

The filter-forward-in chain has no per-port rule, instead it accepts packets for any port (needed in case the filter-FORWARD chain's default policy is "drop"):

{{index . "chain filter-forward-in__bridge1"}}

In chain raw-PREROUTING, there's no "DROP DIRECT ACCESS" rule, so container can be accessed from outside the host:

{{index . "chain raw-PREROUTING"}}

The "dnat" and "masquerade" rules are still in-place. And, if the userland proxy is enabled, it is still started.