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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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.

Linux default route in routing table in VB with NAT

The routing table has the following entries by default with Virtual Box is used with NAT. Destination Gateway Meaning 0.0.0.0 10.0.2.2 The traffic to any undefined network/IP address will be forwarded to the default gateway at 10.0.2.2 10.0.2.0 0.0.0.0 The traffic to the network 10.0.2.0/24 does not need any special gateway. The traffic can be directly forwarded. 169.254.0.0 0.0.0.0 The Link-Local address . If a DHCP server is not available, the server broadcast the it's own IP assignment using the link local address. See ARP. 172.17.0.0 0.0.0.0 The docker bridge since this machine has docker installed.

shortnote

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