employees of organization are not allowed to browse the internet and cannot send any HTTP request. Outgoing packets destined for an HTTP server (port 80) are blocked i.e. Incoming packets for internal host 156.255.7.8.8 are blocked. Incoming packets destined for any internal TELNET server (port 23) are blocked. Incoming packets from network 124.56.0.2 are block (* means any). the packets are filtered according to following specifications : 1. A packet filter firewall filters at the network or transport layer.Īs shown in fig. Packet filter firewall maintains a filtering table that decides which packets are to be forwarded or discarded. For example, the firewall might allow e-mail and Web packets to and from any computer on the intranet, but allow telnet (remote login) packets to and from only selected computers. The firewall accepts or rejects packets based on the packet’s sender, receiver, and port. These firewalls examine only the headers of each packet of information passing to or from the Internet. A more complex firewall might be a computer running UNIX and specialized software.įirewall systems fall into two categories A simple firewall might require only that you configure the software in the router that connects your intranet to your ISP. 2- Control who can telnet into your intranet (a method of logging in remotelyģ- Limit what other kinds of traffic can pass between your intranet and theĪ firewall can be simple or complex, depending on how specifically you want to control your Internet traffic.
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