The most basic function of firewall is the configuration of the packet filtering rules, but in the process of configuration, also have a question, always can't find the answer, and related solutions.
To configure allowed from segment to segment B Telnet function, usually we only need to have A rule in the configuration, the Source Address A, service Source port: any - & gt; Destination Address B, the Service Destination port: 23: the action permit. Only need to configure A such rules, we can from A visit to b.
But from the network level: to establish A session, shake hands at least three interactive information is necessary, B returned network packets from the network, A firewall is A check or not check. Look from actual situation, should be the default is allowed, you have A detail document?
It is to find a related links.

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