a sort of perimeter security. In order to gain access to the network, you must identify yourself to the firewall and it allows you through. There are three main types of firewalls. These are packet filters, circuit-level gateways and application gateways. Packet filters use simple checks to see that the information intended for a specific machine and user only goes to that machine. It does this by checking the computers IP address, which is a unique number assigned to a networked computer (SOS, 2). There are problems with this just as there are problems with passwords. A knowledgeable user can set a computer to "promiscuous" mode, allowing it to read all packets sent through the network. A circuit-level gateway is very much like a packet filter, with the difference being a circuit-level gateway does not give information about the computer doing the sending. It seems like the packet came from the firewall, so even if a promiscuous computer reads the packet, they cannot use the information to access a computer in a higher-level security bracket. There are two types of attacks involved in release of message contents and traffic analysis. One is Passive attack and active attacks. Passive attacks means the eavesdropping on, or monitoring of transmission. The goal of the opponent is to obtain information that is being transmitted. Active attacks present the opposite characteristics of passive attacks, passive attacks are difficult to detect, measures are available to prevent their success. It is difficult to prevent active attacks absolutely, as to do so would require physical protection of all communication facilities and paths at all times. Instead, the goal is to detect them and to recover from any disruption or delays caused by them.Comparing any network operating system is really like comparing an apple to an orange. To judge between the underlying functionality of each operating system geared towards different networking en...
