【正文】 序。把這些支持放進(jìn)內(nèi)核 ,通常會(huì)使這些功能更快、 更強(qiáng)。在微內(nèi)核中，只有為數(shù)不多的關(guān)鍵功能以內(nèi)核方式運(yùn)行，如在幾個(gè)應(yīng)用 程序中如何分配存儲(chǔ)器和處理器時(shí)間，以及軟件進(jìn)程之間的通信等。但是性能要受影響因?yàn)槲募到y(tǒng)和設(shè)備驅(qū)動(dòng)程序不能直接訪問(wèn)應(yīng)用程序所需的所有系統(tǒng)數(shù)據(jù)。 18 世紀(jì)是產(chǎn)業(yè)革命的機(jī)械的系統(tǒng)時(shí)代。 雖然計(jì)算機(jī)業(yè)與其他的工業(yè) (舉例來(lái)說(shuō) ,汽車(chē)和空氣運(yùn)輸 ) 相比較是新興的，但計(jì)算機(jī)在短時(shí)間內(nèi)已經(jīng)表現(xiàn)顯示出進(jìn)步。這些系統(tǒng)叫做計(jì)算機(jī)網(wǎng)絡(luò)。對(duì)于個(gè)人，網(wǎng)絡(luò)提供了多種數(shù)據(jù)和娛樂(lè)資源的共享。局域網(wǎng)能以很快的速度傳撥遍整個(gè)建筑。(也就是 ,沒(méi)有路由器 ) 廣域網(wǎng)被轉(zhuǎn)換。協(xié)議是無(wú)連接的或連接定向的。但是兩者并不相同。 眾所周知的網(wǎng)絡(luò)包括英特網(wǎng)，自動(dòng)柜員機(jī)網(wǎng)絡(luò)，乙太網(wǎng)絡(luò) , 和 IEEE 無(wú)線的區(qū)域網(wǎng)絡(luò)。 自動(dòng)柜員機(jī)為了數(shù)據(jù)的傳輸被廣泛用于電話系統(tǒng)。 電磁的光譜 當(dāng)電子移動(dòng)的時(shí)候 , 他們產(chǎn)生能繁殖過(guò)空間的電磁波。這個(gè)功能雜數(shù)據(jù)鏈路層顯得更恩鮮明。最后，當(dāng)來(lái)源和目的地是在不同的網(wǎng)絡(luò)中的時(shí)候 ,新的問(wèn)題就會(huì)發(fā)生。 IP電話軟件交換 自電話發(fā)明以來(lái)，電信設(shè)備都是基于電路技術(shù) ， 兩個(gè)通信端點(diǎn)之間需要專用的通道。這樣的交換機(jī)是利用 P交換技術(shù)代替專用的電路交換硬件 . 一臺(tái)用英特爾奔騰處理器運(yùn)行微軟 Windows NT IP電話交換的服務(wù)器足以同時(shí)處理成百上千個(gè)電話呼叫。 軟件，如在公司通信環(huán)境中用的專用交換機(jī) (PBX)應(yīng)用程序 ,電話局環(huán)境中用的自動(dòng)通話分配，以及控制通話路由和數(shù)據(jù)集成的計(jì)算機(jī)電話集成 (CTI)。 支持的傳輸技術(shù)取包交換的形式，即通話路由器在一個(gè)包一個(gè)包的基礎(chǔ)上決 定數(shù)據(jù)和聲音走哪條路由 . 利用包通信的價(jià)格優(yōu)勢(shì)如此巨大 ,以至整個(gè)業(yè)界已經(jīng)組織起來(lái)，把基于電路的語(yǔ)音轉(zhuǎn)變成包語(yǔ)音，再把轉(zhuǎn)換過(guò)的語(yǔ)音在包網(wǎng)絡(luò)上通過(guò)路由傳輸，然后再轉(zhuǎn)換成基于電路的語(yǔ)音。而后，它又被用作傳輸和訪問(wèn)科研信息的通道。它使公司在遠(yuǎn)地的用戶通過(guò)因特網(wǎng)鏈路合法訪問(wèn)存儲(chǔ)在總公司服務(wù)器中有即限制的公司信息。 由于它必 須是機(jī)構(gòu)之間安全的網(wǎng)絡(luò)，所以安且是頭等重要的。 作為一種附加的措施，訪問(wèn)控制過(guò)程規(guī)定了誰(shuí)能訪問(wèn)外特網(wǎng)、獲得哪能些信息和服務(wù)種類。 外特網(wǎng)應(yīng)該允許生意上的合作伙伴快速、有效地獲得正確的信息服務(wù)。使用一個(gè)公共外特網(wǎng)的所有單位都必須確保他們做生意的系統(tǒng)和過(guò)程能做到天衣無(wú)縫般的結(jié)合。s characteristic in law from the policy. The system of information safety of a country includes the regulation and policy of the country in fact, and the development platforms of technology and market. Our country should put forth effort to develop one39。t prevent ing from the persons who turn traitor of inside and not careful threats brought of users , can39。 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 wal。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。 Second, the security mechanism and technology of the work should be changed constantly。這就增加了管理和集成的復(fù)雜度。 由于外特網(wǎng)涉及二個(gè)以上的企業(yè)，必須預(yù)先考慮到公司之間要結(jié)合在一起的有關(guān)方面。 但在著手采用外特網(wǎng)之前，各單位必須問(wèn)問(wèn)自己，他們已有的正在 用的做生意