【正文】 行縝密的 設(shè)計(jì)，來對企業(yè)內(nèi)網(wǎng)包括防火墻本身實(shí)施保護(hù)。在絕大多數(shù)網(wǎng)絡(luò)環(huán)境的實(shí)現(xiàn)中它們都是應(yīng)該對外加以屏蔽的。 利用這個協(xié)議，遠(yuǎn)程主機(jī)可以監(jiān)視、控制網(wǎng)絡(luò)上的其它網(wǎng)絡(luò)設(shè)備。 20 對外屏蔽簡單網(wǎng)管協(xié)議 SNMP： （ 2）對外屏蔽遠(yuǎn)程登錄協(xié)議 tel 首先， tel 是一種不安全的協(xié)議類型。其次， tel 可以登錄到大多數(shù)網(wǎng)絡(luò)設(shè)備和 UNIX 服務(wù)器，并可以使用相關(guān)命令完全操縱它們。 對外屏蔽遠(yuǎn)程登錄協(xié)議 tel： （ 3）對外屏蔽其它不安全的協(xié)議或服務(wù) 這樣的協(xié)議主要有 SUN OS 的文件共享協(xié)議端口 2049，遠(yuǎn)程執(zhí)行（ rsh）、遠(yuǎn)程登錄（ rlogin）和遠(yuǎn)程命令（ rcmd）端口 51 51 514，遠(yuǎn)程過程調(diào)用（ SUNRPC）端口 111。 （ 4）針對 DoS 攻擊的設(shè)計(jì) DoS 攻擊（ Denial of Service Attack，拒絕服務(wù)攻擊）是一種非常常見而且極具破壞力的攻擊手段，它可以導(dǎo)致服務(wù)器、網(wǎng)絡(luò)設(shè)備的正常服務(wù)進(jìn)程停止，嚴(yán)重時會導(dǎo)致服務(wù)器操作系統(tǒng)崩潰。 21 為了阻止黑客入侵路由器，必須對路由器的訪問位置加以限制。這時，可以使用ACCESSCLASS 命令進(jìn)行 VTY 訪問控制。它可以為家庭辦公用戶和出差在外的員工提供移動接入服務(wù) 。不同的廣域網(wǎng)連接類型提供的服務(wù)質(zhì)量不同，花費(fèi)也不相同。 異步撥號連接屬于電路交換類型的廣域網(wǎng)連接，它是在傳統(tǒng)公共交換電話網(wǎng)（ Public Switched Telephone Network， PSTN）上提供服務(wù)的。因?yàn)槟壳按嬖谥罅堪惭b好的電話線，所以這樣的環(huán)境是最容易滿足的。 廣域網(wǎng)連接可以采用不同類型的封裝協(xié)議，如 HDLC、 PPP 等。也是本設(shè)計(jì)所采用的異步連接封裝協(xié)議。 PAP 是一個簡單的、實(shí)用的身份驗(yàn)證協(xié)議。如果認(rèn)證成功，在通信過程中不再進(jìn)行認(rèn)證。 CHAP 認(rèn)證比 PAP 認(rèn)證更安全，因?yàn)?CHAP 不在線路上發(fā)送明文密碼，而是發(fā)送經(jīng)過摘要算法加工過的隨機(jī)序列，也被稱為 挑戰(zhàn)字符串 。因此，非法 用戶就算截獲并成功破解了一次密碼，此密碼也將在一段時間內(nèi)失效。這需要耗費(fèi)較多的 CPU 資源，因此只用在對安全要求很高的場合。 由于技術(shù)限制，這里就不進(jìn)行詳細(xì)的配置。 服務(wù)器模塊設(shè)計(jì) 服務(wù)器模塊用來對企業(yè)網(wǎng)的接入用戶提供各種服務(wù)。 企業(yè)網(wǎng) 提供的常見的服務(wù)（服務(wù)器）包括： WEB 服務(wù)器：提供 WEB 網(wǎng)站服務(wù)。 內(nèi)部 IP： 外部 IP： 數(shù)據(jù)庫服務(wù)器：提供各種數(shù)據(jù)庫服務(wù) 。然而，技術(shù)是網(wǎng)絡(luò)組建的主要考慮因素，但是網(wǎng)絡(luò)的構(gòu)建往往受到經(jīng)費(fèi)的制約，因此，高的性價(jià)比是決定的因素。另外，在網(wǎng)絡(luò)設(shè)備的選擇中，重要的經(jīng)驗(yàn)還有： ⑴ 廠家的品牌因素 網(wǎng)絡(luò)的核心設(shè)備決定了整個系統(tǒng)的穩(wěn)定性，因此，廠商的口碑非常重要，如IBM、 Cisco、 Microsoft 等，這些公司具備優(yōu)秀的產(chǎn)品性能、良好的售后服務(wù)、雄厚的研發(fā)實(shí)力等。因此，采用同一品牌的設(shè)備，有著明顯的優(yōu)勢，如網(wǎng)絡(luò)核心構(gòu)架主要采用了 Cisco 的設(shè)備等。例如，我們在軟件系統(tǒng)上，主要采用了微軟的系統(tǒng)平臺，在打印輸出設(shè)備上，主要采用 HP 的產(chǎn)品等。 24 參考文獻(xiàn) [1] Steve McQuerry. CCNA 自學(xué)指南： Cisco 網(wǎng)絡(luò)設(shè)備互連 .人民郵電出版社，2021 [2] Diane Teare、 Catherine Paquet. 園區(qū)網(wǎng)絡(luò)設(shè)計(jì) .人民郵電出版社， 2021 [3] Richard Deal. CCNA 學(xué)習(xí)指南 . 人民郵電出版社， 2021 [4] 崔北亮 . CCNA 學(xué)習(xí)與實(shí)驗(yàn)指南 . 電子工業(yè)出版社， 2021 [5] Kevin Wallace. CCNP TSHOOT 認(rèn)證考試指南 . 人民郵電出版社， 2021 [6] Wendell Odom. CCNP ROUTE 認(rèn)證考試指南 . 人民郵電出版社， 2021 [7] David Hucaby. CCNP SWITCH 認(rèn)證考試指南 . 人民郵電出版社， 2021 [8] 王相林 . 組網(wǎng)技術(shù)與配置 . 清華大學(xué)出版社， 2021 25 致謝 這次畢業(yè)論文能夠得以順利完成，并非我一人之功勞，是所有指導(dǎo)過我的老師，幫助過我的同學(xué)，一直關(guān)心支持著 我的朋友和家人對我的教誨、幫助和鼓勵的結(jié)果。 感謝班主任劉瑩老師，在工作之余指導(dǎo)我的學(xué)習(xí)與生活。 感謝身邊所有的朋友與同學(xué)，謝謝你們四年來的關(guān)照與寬容，與你們一起走過的繽紛時代，將會是我一生最珍貴的回憶。t agree with the disciplinary action your employer has taken against you ? your employer dismisses you and you think that you have been dismissed unfairly. For more information about dismissal and unfair dismissal, see Dismissal. You can make a claim to an employment tribunal, even if you haven39。t charge you more than 35% of your pensation if you win the case. If you are thinking about signing up for a damagesbased agreement, you should make sure you39。s antiracism taskforce, is in London for the Football Association39。s Premier League match at Chelsea on Sunday. I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport. For me it39。s 21 win. Michel Platini, president of European football39。s actions. CSKA said they were surprised and disappointed by Toure39。 May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it. 一字開頭的年齡已經(jīng)到了尾聲?？傆X得自己自己似乎應(yīng)該去做點(diǎn)什么，或者寫點(diǎn)什么。 The end of our life, and can meet many things really do? 而窮盡我們的一生，又能遇到多少事情是真正地非做不可？ During my childhood, think lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional。t really grow up, it seems is not so important。t want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the pitch he has sweat profusely, looked at his thrown a basketball hoops, suddenly found himself has already can39。 Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time. 原來，這個世界上，對某個事件能產(chǎn)生化學(xué)反應(yīng)的，除了非做不可的堅(jiān)決，還有，時間。s time, your ideas are always special to clear. Want, want, line is clear, as if nothing could shake his. Also once seemed to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, just green years oneself give oneself an arm injection, or is a selfrighteous spiritual. 一個人的時候，自己的想法總是特別地清晰。也曾經(jīng)好像已經(jīng)下定了決心去做某件事，但更多的時候是最后又打起了退堂鼓。那些曾經(jīng)所謂的非做不可，只是青蔥年華里自己給自己注射 的一支強(qiáng)心劑，或者說，是自以為是的精神寄托罷了。 Those were broken into various shapes of stationery。 Have declared the end of the encounter that haven39。突然想到那件藍(lán)格子襯衫；那些被折成各種各樣形狀的信紙；那段從街角深巷伊始的友誼；還有那場還沒有開始就宣告了終結(jié)的邂逅計(jì)劃 …… 那些年那些天的非做不可，終于和青春一樣，都將在我們的人生中謝幕。ll be traveling fast, so despite the distance, it will not be like 28 diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jump When he jumps, he is expected to reach the speed of sound 690 mph (1,110 kph) in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him pletely. If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it39。t. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters). cause there