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网络应用

网络应用. 网络安全. 不要以明文传输任何重要的数据 不要以明文存储重要的数据 多种加密算法使得数据难以被解出明文 使用不同的加密密钥和解密密钥. DNS. DNS. eMail. 信封和内容. eMail-RFC822. Some fields used in the RFC 822 message header. eMail-RFC822. Some fields used in the RFC 822 message header. MIME – Multipurpose Internet Mail Extensions.

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网络应用

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  1. 网络应用

  2. 网络安全 • 不要以明文传输任何重要的数据 • 不要以明文存储重要的数据 • 多种加密算法使得数据难以被解出明文 • 使用不同的加密密钥和解密密钥

  3. DNS

  4. DNS

  5. eMail • 信封和内容

  6. eMail-RFC822 • Some fields used in the RFC 822 message header

  7. eMail-RFC822 • Some fields used in the RFC 822 message header

  8. MIME – Multipurpose Internet Mail Extensions Problems with international languages: • Languages with accents (French, German). • Languages in non-Latin alphabets (Hebrew, Russian). • Languages without alphabets (Chinese, Japanese). • Messages not containing text at all (audio or images).

  9. MIME (2) RFC 822 headers added by MIME.

  10. MIME (3) The MIME types and subtypes defined in RFC 2045.

  11. MIME (4) A multipart message containing enriched and audio alternatives.

  12. Message Transfer Transferring a message from elinore@abc.com to carolyn@xyz.com.

  13. 简单邮件传输协议 • 当邮件传送程序与远程服务器通信时，它构造了一个T C P连接并在此上面进行通信。一旦连接存在，这两个程序就遵循简单邮件传输协议（ Simple Mail Transfer Protocol，S M T P），它允许发送方说明自己，指定接收方，以及传送电子邮件信息。

  14. Final Delivery (a) Sending and reading mail when the receiver has a permanent Internet connection and the user agent runs on the same machine as the message transfer agent. (b) Reading e-mail when the receiver has a dial-up connection to an ISP.

  15. POP3 Using POP3 to fetch three messages.

  16. # telnet 10.12.13.55 110 Trying 10.12.13.55... Connected to 10.12.13.55. Escape character is '^]'. +OK Hello there. user gengcg +OK Password required. pass 1234 +OK logged in. list +OK POP3 clients that break here, they violate STD53. 1 1473 2 6499 3 399 4 426 5 298 6 266 .

  17. retr 1 +OK 1473 octets follow. Delivered-To: gengcg@digitec.dot66.org Return-Path: <> Received: from dot66.net ([::ffff:10.12.13.169]) by digitec.dot66.org with esmtp; Fri, 31 May 2002 11:42:49 +0800 Received: (qmail 27799 invoked for bounce); 31 May 2002 11:13:07 -0000 Date: 31 May 2002 11:13:07 -0000 From: MAILER-DAEMON@dot66.net To: gengcg@digitec.dot66.org Subject: failure notice Hi. This is the qmail-send program at dot66.net. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out. <gengcg@263.sina.com>: 210.83.130.82 does not like recipient. Remote host said: 553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1) Giving up on 210.83.130.82. --- Below this line is a copy of the message. Return-Path: <gengcg@digitec.dot66.org> Received: (qmail 27797 invoked from network); 31 May 2002 11:12:49 -0000 Received: from unknown (HELO digitec.dot66.org) (10.12.13.55)

  18. IMAP A comparison of POP3 and IMAP.

  19. 文件传输协议 • 因特网上使用最广泛的文件传输服务使用文件传输协议（ File Transfer Protocol，F T P）。 • F T P是因特网中仍然在使用的最古老的协议之一。

  20. FTP命令 • 回车控制（carriage control） • 包含一些几乎不会执行的选项（例如，允许与两个远程站点同时进行通信的p r o x y命令）。

  21. WWW

  22. URLs – Uniform Resource Locaters Some common URLs.

  23. Statelessness and Cookies Some examples of cookies.

  24. HTML – HyperText Markup Language (a) The HTML for a sample Web page. (b) The formatted page. (b)

  25. HTML (2) A selection of common HTML tags. some can have additional parameters.

  26. Forms (a) An HTML table. (b) A possible rendition of this table.

  27. Forms (2) (a) The HTML for an order form. (b) The formatted page. (b)

  28. Forms (3) A possible response from the browser to the server with information filled in by the user.

  29. Dynamic Web Documents Steps in processing the information from an HTML form.

  30. Dynamic Web Documents (2) A sample HTML page with embedded PHP.

  31. Dynamic Web Documents (3) (a) A Web page containing a form. (b) A PHP script for handling the output of the form. (c) Output from the PHP script when the inputs are "Barbara" and 24 respectively.

  32. Client-Side Dynamic Web Page Generation Use of JavaScript for processing a form.

  33. Client-Side Dynamic Web Page Generation (2) (a) Server-side scripting with PHP. (b) Client-side scripting with JavaScript.

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