Abstract: With the turn of this century, many researchers
started showing interest in Embedded Firewall (EF) implementations.
These are not the usual firewalls that are used as checkpoints at network gateways. They are, rather, applied near those hosts that need protection. Hence by using them, individual or grouped network
components can be protected from the inside as well as from external attacks.
This paper presents a study of EF-s, looking at their architecture and problems. A comparative study assesses how practical each kind is. It particularly focuses on the architecture, weak points, and
portability of each kind. A look at their use by different categories of users is also presented.