【正文】 t give up our girls for a dozen fortunes. 。s older sisters were just out, and Meg caught frequent glimpses of dainty ball dresses and bouquets, heard lively gossip about theaters, concerts, sleighing parties, and merrymakings of all kinds, and saw money lavished on trifles which w ould have been so precious to her. Poor Meg seldom plained, but a sense of injustice made her feel bitter toward everyone sometimes, for she had not yet learned to know how rich she was in the blessings which alone can make life happy. Jo happened to suit Aunt March, who was lame and needed an active person to wait upon her. The childless old lady had offered to adopt one of the girls when the troubles came, and was much offended because her offer was declined. Other friends told the Marches that they had lost all chance of being remembered in the rich old lady39。, and her chief trouble was poverty. She found it harder to bear than the others because she could remember a time when home was beautiful, life full of ease and pleasure, and want of any kind unknown. She tried not to be envious or discontented, but it was very natural that the young girl should long for pretty things, gay friends, acplishments, and a happy life. At the Kings39。t ge t any of it. And when they went away, leaving fort behind, I think there were not in all the city four merrier people than the hungry little girls who gave away their breakfasts and contented themselves with bread and milk on Christmas morning. That39。d do it, said Mrs. March, smiling as if satisfied. You shall all go and help me, and when we e back we will have bread and milk for breakfast, and make it up at dinnertime. They were soon ready, and the procession set out. Fortunately it was early, and they went through back streets, so few people saw them, and no one laughed at the queer party. A poor, bare, miserable room it was, with broken windows, no fire, ragged bedclothes, a sick mother, wailing baby, and a group of pale, hungry children cuddled under one old quilt, trying to keep warm. How the big eyes stared and the blue lips smiled as the girls went in. Ach, mein Gott! It is good angels e to us! said the poor woman, crying for joy. Funny angels in hoods and mittens, said Jo, and set them to laughing. In a few minutes it really did seem as if kind spirits had been at wor k there. Hannah, who had carried wood, made a fire, and stopped up the broke n panes with old hats and her own cloa k. Mrs. March gave the mother tea and gruel, and forted her with promises of help, while she dressed the little baby as tenderly as if it had been her own. T he girls meantime spread the table, set the children round the fire, and fed them like so many hungry birds, laughing, talking, and trying to understand the funny broken English. Das ist gut! Die Engel kinder! cried the poor things as they ate and warmed their purple hands at the fortable blaze. T he girls had never been c alled angel children before, and thought it very agreeable, especially Jo, who had been considered a `Sancho39。m glad you began at once, and hope you will keep on. But I want to say one word before we sit down. Not far away from here lies a poor woman with a little newborn baby. Six children are huddled into one bed to keep from freezing, for they have no fire. There is nothing to eat over there, and the oldest boy came to tell me they were suffering hunger and cold. My girls, will you give them your breakfast as a Christmas present? They were all unusually hungry, having waited nearly an hour, and for a minute no one spoke, only a minute, for Jo exclaimed impetuously, I39。, while Beth ran to the window, and picked her finest rose to ornament the stately bottle. You see I felt ashamed of my present, after reading and talking about being good this morning, so I ran round the corner and changed it the minute I was up, and I39。t mean anyone should know till the time came. I only meant to change the little bottle for a big one, and I gave all my money to get it, and I39。s Mother. Hide the basket, quick! cried Jo, as a door slammed and steps sounded in the hall. Amy came in hastily, and looked rather abashed when she saw her sisters all waiting for her. Where have you been, and what are you hiding behind you? asked Meg, surprised to see, by her hood and cloak, that lazy Amy had been out so early. Don39。, looking troubled. It39。s initials are ., and I don39。. How funny! cried Jo, taking one up. Isn39。s gone and put `Mother39。 特此聲明！ 作者簽名： 年 月 日 he new army slippers. How nice my handkerchiefs look, don39。 （ 5）學校可以公布學位論文的全部或部分內容（保密學位論文在解密后遵守此規(guī)定）。 （ 3）學?？梢詫W術交流為目的復制、贈送和交換學位論文。 關于學位論文使用權和研究成果知識產權的說明 本人完全了解成都信息工程學院有關保管使用 學位論文的規(guī)定，其中包括： （ 1）學校有權保管并向有關部門遞交學位論文的原件與復印件。文中除了特別加以標注地方外，不包含他人已經發(fā)表或撰寫過的研究成果，也不包含為獲得成都信息工程學院或其他教學機構的學位或證書而使用過的材料。 致 謝 本文是在李文濤老師和韓桂華老師的熱情關心和指導下完成的，他們淵博的知識和嚴謹?shù)闹螌W作風使我受益匪淺，對順利完成本課題起到了極大的作用。 [6] 謝希仁 .計算機網絡 (第四版 )[M]. 北京 : 電子工業(yè)出版社 ,。 [4] 唐正軍 .入侵檢測技術導論 [M]. 北京 : 機械工業(yè)出版社 ,。 [2] 宋勁松 .網絡入侵檢測 [M]. 北京 : 國防工業(yè)出版社 , 。 由于能力和水平所限，該系統(tǒng)的設計和實現(xiàn)還有很多工作要做，并需進一步完善。本論文只完成了入侵檢測系統(tǒng)的前期工作，即捕獲網絡上的數(shù)據包，通過對這些捕獲的數(shù)據包進行分析，可以為后面的響應模塊提供數(shù)據輸入。因此，入侵檢測技術的進一步完善是研究的重點問題。不斷增大的網絡流量對入侵檢測的實時性提出了考驗 。入侵檢測技術還面臨著許多新的問題，如攻擊者的水平不斷提高，攻擊手段越來越復雜細致 。一個好的 Intra 的安全解決方案應該既滿足安全需求，又具有足夠的透明性、可用性和 易管理性。 測試結果 以下為檢測模塊測試效果圖： 圖 51 檢測模塊測試圖 1 圖 52 檢測模塊測試圖 2 結果分析如表 51： 表 51 結果分析表 測試目的 測試結果 分析 數(shù)據包捕獲 正常 能 夠尋獲捕獲共享網段上所有數(shù)據包 數(shù)據包分析 正常 能夠將捕獲的數(shù)據包進行協(xié)議分析，以得到響應模塊需要的結果 結 論 網絡安全防范是一個整體的行為，涉及多層次多方面的保護和技術，如防火墻、訪問控制、認證措施、檢測工具、弱點掃描、安全培訓等，防范目標就是使得入侵者突破安全防線更加困難，而防衛(wèi)和檢測入侵更加容易。 測試目的 測試目的主要為以下兩點： （ 1） 測試系統(tǒng)是否能夠從共享網段中捕獲到數(shù)據包。 5. 系統(tǒng)測試與分析 網絡數(shù)據包的捕獲和分析是整個網絡入侵 檢測系統(tǒng)實現(xiàn)的基礎，只有獲得了數(shù)據源之后，系統(tǒng)的響應模塊才能夠檢測出當前是否有攻擊行為或者攻擊企圖。具體實現(xiàn)效果如圖 44 所示： 圖 44 檢測模塊效果圖