Host network mode

In host mode, tasks share the host's network namespace directly. The container's networking configuration is tied to the underlying Amazon ECS Managed Instances host instance that you specify using the networkConfiguration parameter when you create an Amazon ECS Managed Instances capacity provider.

There are significant drawbacks to using this network mode. You can’t run more than a single instantiation of a task on each host. This is because only the first task can bind to its required port on the Amazon EC2 instance. There's also no way to remap a container port when it's using host network mode. For example, if an application needs to listen on a particular port number, you can't remap the port number directly. Instead, you must manage any port conflicts through changing the application configuration.

There are also security implications when using the host network mode. This mode allows containers to impersonate the host, and it allows containers to connect to private loopback network services on the host.

Use host mode only when you need direct access to host networking or when migrating applications that require host-level network access.