Figure 24.1 illustrates three different ways you might use ICF:
With a standalone dial-up or broadband connection (computer A)
With a shared dial-up connection (computers B and C)
With a shared broadband connection (computers D and E)
In each case, ICF is enabled only on the connection that attaches to the distrusted network. It is not enabled on the connections for inside the network because it would block the computers' ability to interact with each other ...