Running a docker container in host network namespace

Docker is utilizing network namespaces of Linux to provide the isolation for the containers. However, it is possible to define in which network namespace the container should be running. Hence, we can also get a container running in the host network.

docker run --name hostbusybox --network=host busybox

Since the above container is running in the host network, the interface of the container can be seen with the following command

ip addr list

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Linux as a software Switch / Router Bridge

Network Interfaces Creating two network interfaces in Linux sudo ip link add eth0dummy1 type dummy sudo ip link add eth0dummy2 type dummy Setting those interfaces up sudo ip link set up eth0dummy1 sudo ip link set up eth0dummy2 Showing existing interfaces ip addr list MAC is assigned to eth0dummy1 and eth0dummy2 interfaces Bridge Creating the bridge sudo brctl addbr dummybridge Setting the bridge up sudo ip link set up dummybridge Adding interfaces to the bridge sudo brctl addif dummybridge eth0dummy1 eth0dummy2 Showing existing bridges sudo brctl show Showing virtual ports and MAC addresses sudo brctl showmacs dummybridge virtual port 1 attached to eth0dummy1 interface MAC and port 2 to eth0dummy2 MAC Router Converting the bridge to a router by assigning a L3 address. sudo ip addr add 172.16.0.1/24 dev dummybridge Reference

Hub vs Bridge vs Switch

Hub Layer: Physical Layer Connects network segments (wires) and broadcast traffic (without knowing to know MAC). Bridge Layer - Data Link Layer Connects two network segments (wires) and forward packets based on the MAC. Can be a software or a hardware. Switch Layer - Data Link Layer Multiple bridges are implemented in a switch hence it can forward traffic between more than two network segments based on the MAC.

shortnote

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