Discarding package which spreads from the public network, but these packages have in your network source address, thus reduces the IP fraudulence attack.
Discarding contains the source routing information the package, reduces the source route attack. Must remember, in the source route attack, the pocket which spreads including the routing information, it covered the package to adopt the primary route through the network, possibly will bypass the existing safety procedure. Through neglects the source road 2. condition/dynamic examination firewall
The condition/dynamic examination firewall, attempts to track through firewall's network connections and the package, such firewall may use the standard which a group attaches, by determined whether to permit and refuses to correspond. It is in used the basic package to filter in firewall's correspondence to apply some technologies to do this some.
When the package of filtration firewall saw that a network package, the package is the isolated existence. It will not have the history which or the future the firewall cared. The permission and a rejection package of decision are decided the information which completely own contains in the package, like source address, destination address, port number and so on. In the package has not contained any describes it in the information flow position information, then this diaper thought that is the non-condition; It is only the existence.
Not only has the condition package of inspection firewall track is the information which in the package contains. In order to track a package of condition, the firewall also record useful information helps the recognition package, for example the existing network connections, the data spread the request and so on.
For example, if spreads pocket including video frequency data stream, but the firewall already had possibly recorded the related information, was about is located at the specific IP address the application procedure to send out the package of source address request video signal recently the information. If spreads the package is must pass to sends out the request the same system, the firewall carries on the match, the package may allow to pass.
A condition/dynamic examination firewall may interrupt the correspondence which all spreads, but permits the correspondence which all spreads. Because the firewall track interior exits the request, possesses the data which spreads according to the request to allow to pass, is closed until the connection. Then has not been requested to spread the correspondence to interrupt.
If is moving a server in the firewall, the disposition will become slightly complex somewhat, but a condition package of inspection will be very powerful and the compatible technology. For example, may dispose the firewall Cheng Zhi to permit the correspondence which enters from the specific port, only may pass to the specific server. If is moving the Web server, the Web server which the firewall only spreads to 80 ports the correspondence which sends assigns.
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