Just as a building or vehicle uses specially constructed walls to prevent the spread of fire, so computer systems use firewalls to prevent or limit access to certain applications or systems and to protect systems from malicious attacks.
To create a firewall under QNX Neutrino, you can use a combination of:
For more information, see pf-faq at ftp://ftp3.usa.openbsd.org/pub/OpenBSD/doc/ in the OpenBSD documentation.