Sweep across the whole world quickly already in the application of each Internet of late when, " the network is safe " the care that the problem also began to arouse most person, and base at this problem development goes "Firewall"(firewall) such child, use it to come to those who prevent exterior network crasher inbreak. This article should make "Firewall" and "Linux" a tie, introductory everybody comes the firewall of erect Linux.
Each old friend new friend of Linux was not for ages on paper meet, hope can this rare opportunity uses Jie short article and authority are great share this little caution of our person to get.
Since national information freeway (NII) since driving, consecutive the elaboration of TANET, SeedNet, HiNet, internet has become the enthusiastic topic of each magazine almost, and " join Internet, use Internet " also make a kind of way that builds company image. It is under disturbance of an Internet agitation, somebody begins concern so called " the network is safe " problem. Because of Internet open, and make of all members indebted, but also open because of his, should consider this more so " the network is safe " problem. If this we should talk, be inscribed even if begin consequently formerly because of this, "Firewall" (firewall) namely base at this " the network is safe " think a child under.
We are OK interiorly network and outside between network join, install a machine that has Firewall function, use it to filter the data that transmits each other between these two networks, like that after is restricted through the set of relevant software different the network function that place of the person that use can use. Should convey to must be passed through to the data of in-house network by exterior network installed Firewall this machine will transmit, the data of in-house network also passes through this Firewall to convey the data correctly a destination that goes up at exterior network. Became the transfer station between the network as the machine of Firewall. Because this is become " outside astral caller " when arriving at, arrive at Firewall only by the footstep at him, be in so the poorest condition is this " Firewall machine was destroyed! ! " , but in-house network can have escaped to rob however and " live on a degradation " come down, base at sacrifice small I am finished big below my principle, such cost is worthiness it seems that.
Although such formalities appears to comparative trival, but also because such, can prevent crasher of a few exterior networks more or less inbreak, in order to ensure the safety of in-house network. The communication of ministry network outside also can restricting in-house network to be opposite on the other hand, do another network data to flow accuse a canal. Of course, for this safe problem, we must sacrifice many " convenience " , " speed " go up enjoy, but the thing always can have a kind that make up for, these will be the content that we involve.
The erect of Firewall condition is not exclusive, in light of the function that this wants completely to regard industry system and Firewall software. The graph above is a the simplest Firewall framework. The word after of a few Firewall was told in front, mix our leading role "Linux" makes a tie, begin to plunge truly our key, " how to use Linux erect a Firewall " .
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