I understand that a firewall is for security purposes and I also understand that hardware and (software (such as Zone Alarm)) firewalls can be configured to block certain inward or outward traffic by specifying certain IP addresses or protocols such as udp, ftp, tcp, http, smtp and so on. What I don’t understand is how some hardware firewalls (such as one that I have) that are not configurable are capable of determining what is acceptable traffic and what is forbidden traffic. IS IT BECAUSE IT ACCEPTS ALL IN COMING TRAFFIC THAT YOU SOLICIT TO AND REJECTS ALL THE REST.