Prerequisite: Download and install OMNeT++ from omnetpp.org.
Recent versions of the OMNeT++ IDE can download and install INET (the latest stable version) for you.
How does it work?
If you skipped this step (opened the workbench but skipped installing INET), nothing is lost:
Both ways, the IDE will download, unzip, and automatically build INET from the sources.
You’ll need manual installation if you downloaded an INET version other than the latest stable one, or you have cloned the INET git repository to the local filesystem. The only “tricky” part is how to import the project into the workspace.
tar xvfz inet-<version>.tgz
Please also read the
INSTALLATION file in the INET sources, as it may contain additional information.