【導(dǎo)讀】它不僅從一般性的防衛(wèi)變成了一種非常普通的防范，而且還從一。種專門的領(lǐng)域變成了無處不在。當(dāng)人類步入21世紀(jì)這一信息社會(huì)、網(wǎng)絡(luò)社會(huì)的。網(wǎng)絡(luò)安全產(chǎn)品有以下幾大特點(diǎn)：第一，網(wǎng)絡(luò)安全來源于安全策略與技術(shù)的多樣化，因此，網(wǎng)絡(luò)安全技術(shù)是一個(gè)十分復(fù)雜的系統(tǒng)工程。全體系，需要國(guó)家政策和法規(guī)的支持及集團(tuán)聯(lián)合研究開發(fā)。安全與反安全就像矛。信息安全是國(guó)家發(fā)展所面臨的一個(gè)重要問題。它對(duì)兩個(gè)或多個(gè)網(wǎng)絡(luò)之間傳輸?shù)臄?shù)據(jù)包如鏈接方式按照一定的。據(jù)驅(qū)動(dòng)型的攻擊。包過濾型產(chǎn)品是防火墻的初級(jí)產(chǎn)品,其技術(shù)依據(jù)是網(wǎng)絡(luò)中的分包傳輸技術(shù)。防火墻通過讀取數(shù)據(jù)包中的地址信息來判斷這些“包”是否來。但包過濾技術(shù)的缺陷也是明顯的?；饓φJ(rèn)為該訪問是不安全的，不能被接受，防火墻將屏蔽外部的連接請(qǐng)求。其缺點(diǎn)是對(duì)系統(tǒng)的整體性能有較大的影響,而。監(jiān)測(cè)型防火墻是新一代的產(chǎn)品,這一技術(shù)實(shí)際已經(jīng)超越了最初的防火墻定義。

　　

【正文】 system is: Can all IPs be visited to the work system in the enterprise ? If the answer is yes , prove the has not taken the corresponding precautionary measures in the Inter yet inside enterprises. As inside work and outside public between work the first protective screen, the fire wall is one of the online security products paid attention to by people at first. Though look theoretically, the fire wall is in the bottom of online security, responsible for the safety certification and transmission among the works, but with the whole development of the safe practice of the work and constant change of work application, the technology of modern fire wall has already moved towards other safe levels not including the Inter progressively , not only should finish the filtration task of the traditional fire wall , still can offer corresponding security service for various kinds of work application at the same time . There are products of many kinds of fire walls that are being developed with such directions as user39。s authentication , preventing the virus and hacker from invading ,etc. safely towards the data in addition. Different according to the technology that the fire wall adopts, we can divide it into four kinds of basic types : Wrap up the filtering type , work address to change NAT , acting as agent type and monitoring type. 1. Wrap up the filtering type It is primary products in the fire wall to wrap up the filtering type products, its technological basis is subcontracting transmission technology in the work. Data of work to regard wrapping up as unit is it transmit to go on , data is it bee certain datum of size wrap up to cut apart, every datum bag will include some specific information, for instance source address , port and goal port ,etc. , address of goal and source of TCP/UDP of data. Fire wall judge through reading the address information in the data bag the is chartered and e from the dependable security website, once find the data from danger website are chartered , the fire wall will keep these data outside of the door . The system manager can make the rule of judging flexibly according to the actual conditions too. Is it filter advantage of technology simple and practical , realize cost to be relatively low , in environment of using under the simple situation to make, can be with the security of the security system to a certain extent of smaller cost. But it is obvious to wrap up the defect of filtering technology. Is it filter technology one based on Inter safe practice totally , can only judge according to source , goal and port that datum make information of the work to make, it is unable to discern on the basis of using the evil intention on floor to invade , the virus attached in hostile Java little procedure and Email . The experienced hacker is very apt to fe IP address, deceive the filtering type fire wall of chartering. 2. The work address transforms NAT Network address change it is one that is it change temporary , external , IP address standard that register IP address to use for. It allows Inter of inside access to woks with privately owned IP address. It still means users should be for IP address that every machine obtains registration in their works. When the inside work visits the outside work through the safe work card , will produce a record of shining upon . System shine upon as one address and port of mask source address and source port that go out, let the address and port of this mask be connected with outside work through the non safe work card, so hide the true inside work address externally. When the outside work visits the inside work through the non safe work card, it does not know the connection situation of the inside work , and just ask to visit through an open IP address and port. OLM fire prevention foot of a wall according to define shining upon rule judge whether these visit is safe good in advance. When according with the rule, the fire wall thinks that it is safe to visit, can accept visit request , can ask to shine upon joining in different inside puters too. As at the rule of according with, fire wall think should it visits to be unsafe, can39。t accept, shielding external connection request fire wall. The course that the work address changes is transparent to user, do not need users to set up , users only need operate the routine. 3. Agent person who act as agent fire wall can known as acting server too, security of it is it higher than make product of filtering etc. to want, and has already begun one floor of development to application. The acting server lies between client and server, has totally prevented the data between the two from being exchanged. According to client, the acting server is equivalent to a real server。 And according to server, the acting server is a real client. Is it at using data of server , is it for the acting server to ask as client datum at first to need, acting server is it ask for datum according to one this to server to ask and then, give data transmission the client by acting server. Because of there is no direct data passway between the outside system and inside server, external evil intention is very difficult to injure to the work system inside enterprises too to encroach on Agent type advantage of fire wall security relatively high, may be to using layer to detect examining and scanning, deal with on the basis of use invasion and virus in layer very much effective. Shorting its whether globality in system can have greater influence, and acting server must use the type to be set up to all that client might produce one by one, have increased the plexity of system management greatly . 4. Monitoring type The monitoring type fire wall is the products of new generation, this technology has already surmounted the initial fire