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小马驹的出现似乎与香港六合彩与油麻地之间有着极其神秘的关系。它似乎总出现在某一特定的时刻。尽管并无足够的事实证明这一点,但在杜元潮的感觉里,其情形就是如此。小马驹一身纯白,身材修长而优美。它不走也不跳,永远是一个脑袋上引、以观苍穹的姿势。这个姿势,富有神性。小马驹身后的桑树一派静穆,在月光下犹如一株株巨大的珊瑚。杜元潮无声响地看着它,居然想像着自己听到了它纯净的鼻息声。春月万里,月色如水似乳,三月 …

小马驹的出现似乎与香港六合彩与油麻地之间有着极其神秘的关系。它似乎总出现在某一特定的时刻。尽管并无足够的事实证明这一点,但在杜元潮的感觉里,其情形就是如此。小马驹一身纯白,身材修长而优美。它不走也不跳,永远是一个脑袋上引、以观苍穹的姿势。这个姿势,富有神性。小马驹身后的桑树一派静穆,在月光下犹如一株株巨大的珊瑚。杜元潮无声响地看着它,居然想像着自己听到了它纯净的鼻息声。春月万里,月色如水似乳,三月的夜,让香港六合彩有微醺之意,也使香港六合彩起一份惶惑与茫然。杜元潮不能久看小马驹,因为久看之下,它就会慢慢变得模糊,直至淡如轻烟,轻轻飘去,仿佛天地间就不曾有过它。有些时候,杜元潮自己也会疑惑:果真有这样一匹小马驹吗?月亮在大放光明,那小马驹周身镶了毛茸茸的银边。杜元潮双眼发涩,微闭一阵,再睁开时,就见天地间白茫茫一片,空空如也……[第68节]鬼雨/梨花雨7(1)雨从早晨就开始下了,不粗也不急,很纯净,很温柔。虽说是个雨天,但天并不显得昏暗,只是觉得天地间飘散着淡淡的烟。小孩子们照样在外面玩耍,偶尔会听到大香港六合彩的骂声:小猴子,你就死在外面让雨淋好了。骂完了,并不固执着让孩子回去,只是嘀咕着,衣服都淋湿了,没换的了。由香港六合彩去,就让香港六合彩穿湿的。香港六合彩百无聊赖地坐在门口,两眼无神、满脸倦色地往门外看,看雨落到水洼里,溅起一个一个水泡泡,那水泡泡鼓起时,很像青蛙鸣叫时嘴巴两侧的气囊。看雨地有香港六合彩在行走,那路像浇了油一般滑,那香港六合彩走得很不容易,即便是聚精会神,也仍然东摇西晃,突然脚一滑,滑倒在烂泥地里,样子很滑稽。见着的香港六合彩,就会禁不住笑起来,就会有一串口水在笑的时候流下来。看河上,河上有个穿蓑衣的放鸭香港六合彩,正撑着小船,将一大群鸭子慢慢地往前赶,那些鸭们可能是吃饱了,没心思再寻觅小鱼小虾了,只管缩着脖子往前游,偶尔,水中有条大鱼一甩尾巴,它们被惊起,炸了窝一般,叫着四处逃散,但过不了一会儿,又汇拢到一起,然后依然缩起脖子,在雨中慢慢往前游去。雨将一切植物洗得干干净净,绿的,红的,黄的,白的,所有的颜色都比以前鲜亮,那颜色仿佛原先是在睡眠中,而现在都被雨唤醒了,流动着生命的光彩。广阔的田野,在这春天的雨中,蓬蓬勃勃地生长着。每一根草茎,每一片叶子,仿佛都朝天空张着欲望的嘴巴,吮吸着飘落下来的甜丝丝的雨。就在这无比寂静的天空下,却又分明有轰隆轰隆的欲望在喧嚣不宁。二傻子在雨地跑着,叫唤着……田埂上,两条牛在一前一后地吃草。雨幕里它们显得很庞大,像两座小山。两座小山在移动着。但,过不了一会儿,后面那座稍大一点儿的山哞的一声鸣叫,朝前面那座稍小点的山急速逼将过去。小山仿佛感到了威胁,就向前跑去。大山便迅猛地追过去。于是,一大一小两座山,就在田野上飞驰着,跳跃着,从田埂到河边,从河边到果园,从果园到野草丛生的荒地。小山终于停住了,那大山忽地向空中跃起,随即落在了小山的脊背上。就在这一时间里,可能有许多双眼睛看到了这两座叠加在一起的山。山的脊梁在痉挛似的耸动着。雨珠从棕色的山梁上纷纷滚落下来,直落到野草丛中。二傻子拿了一根树枝,在山边边上看着,口水不住地从嘴角流下。

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Transcript

  • 1. FAQ’S ABOUT WAP Presented By Abhilash Pillai CSCI 5939-Independent Study
  • 2. Topics Covered
    • Definition of a WAP gateway
    • Architecture of a WAP gateway
    • Configuration of WAP gateway
    • Security over a WAP gateway
    • Definition of WAP server
    • Role of a WAP server
  • 3. Definition of WAP gateway
    • A WAP gateway is a piece of software that has several functions in the chain between the WAP device and the web server.
    • When implementing services in Wireless Application Protocol(WAP),information is translated into Wireless Markup language(WML) by a two way device called a WAP gateway
  • 4. Architecture of WAP Gateway
    • Components of architecture
    • Wireless Device
    • WAP Gateway
    • HTTP Server
  • 5. Explanation Of Architecture
    • The data transfer procedure is as follows
    • Client sends a WSP request to WAP gateway
    • WAP gateway decodes the WSP request into HTTP request
    • WAP gateway sends the HTTP request to HTTP server
    • WAP gateway receives the HTTP reply from HTTP server
    • WAP gateway encodes the HTTP reply headers into WSP reply headers
    • WAP gateway uses WML compiler to encode the received WML data to WMLC format ,which is more compact
    • WAP gateway sends WSP reply
    • Client parses WSP reply and presents data.
  • 6. Architecture cont…….
    • From the previous procedure we can see the main tasks for a WAP gateway are
    • Communication with clients (based on WSP)
    • Decoding WSP requests into HTTP requests
    • Communication with HTTP server (based on HTTP)
    • Encoding HTTP reply headers into WSP Reply headers
    • Compile WML data into WMLC format
  • 7. Configuration of WAP gateway
    • The WAP gateway and web server together form the WAP server are placed in outside the content providers domain
    • System is less secure
  • 8. Configuration Cont…..
    • The WAP server ie the WAP gateway and the web server are placed in the content providers domain
    • System is more secure
  • 9. How the configuration works
    • Mobile user types in the URL for a site on the WAP device
    • The WAP device first checks if it already has an open connection. 
    • If not it dials the modem attached to a dial-in server (RAS, or Remote Access Service).  This server gives the WAP device access to the protocols it needs. 
    • These protocols are the same lower level protocols as a normal Internet Service Provider will give you, i.e. PPP (Point-to-Point Protocol).
  • 10. Description Cont….
    • After the PPP provider has given the WAP device the required protocols and assigned it an IP address, the request for the URL is then sent to the WAP Gateway. 
    • The WAP Gateway, now under "control" of the WAP device requests the URL with a normal HTTP request. 
    • The WAP Gateway is the link between the wireless and the Internet, basically giving the WAP device access to the common Internet.
  • 11. Description Cont….
    • On the Internet, the web server receives the request from WAP Gateway and sends out the contents located at the URL back.
    • Finally, back at the WAP device that requested the URL, the WML browser, when receiving the tokenized WML code renders the contents on the WAP device's display to present the first card off of the deck on the screen for the user
    • To sum up, the client makes a request. This request is received by a WAP gateway that then processes the request and formulates a reply using WML and send back to the client for display.  This process is very similar in concept to the standard HTTP transaction involving client Web browsers
  • 12. Security Issues
    • For a short span of time when the data is unencrypted in the WAP gateway; is major security issue
    • It is upto the vendors discretion to make the gateway as secure as possible
  • 13. Security issues Contd…..
    • The second issue with security is that of certificates that are provide for the device
    • This certificate is used to access the various services for a particular user
    • If the mobile device is lost it is possible for any user who possess that mobile device to access the various services
    • Thus for this purpose in the new WTLS specification the idea of pins were introduced ie a secure token id.thus the user is supposed to reveal the token before using the services.
  • 14. What is a WAP server
    • A WAP Server is nothing more than a normal web server and a WAP gateway-like device built into one.
    • The WAP server can plug a few holes that are currently unplugged in the WAP environment .
    • Since the WAP server contains a gateway, the third party gateway usually hosted by the mobile operator can be skipped, and the host of the WAP content will have full control over the encrypted stream
  • 15. Is WAP secure with SSL and WTLS?
    • SSL or Secure Sockets Layer which is widely used in the "web" world to encrypt the data stream between the browser and the webserver is actually also used in the WAP environment.
    • SSL is only used between the webserver and the WAP gateway. Between the WAP gateway and the WAP device, a similar system called WTLS or Wireless Transport Layer Security. WTLS is specialized for the wireless environment.
    • SSL and WTLS on their own provide adequate security for most applications. However, there is a potential security problem where the two protocols meet, and that's inside the WAP gateway .
  • 16. Models of WAP system
    • | |
    • [WAP device]--|------[WAP gateway]---| [Content Server]
    •  -|---  | {unprotected}  -|- 
    • WTLS | SSL
    • (Firewall) | | (Firewall)
    • SSL is not directly compatible with WTLS, so the WAP gateway must decrypt the SSL protected data stream coming from the webserver and then re-encrypt it using WTLS before passing the data on to the WAP device
    • Inside the memory of the WAP gateway, the data is unprotected
  • 17. Models Cont….
    • A more secure model but with tradeoff
    • [WAP device]--|-----------| [WAP Server acting as WAP gateway]
    •  -|-------- 
    • WTLS |
    • (Firewall) | | (Firewall)
    • WAP players are developing solutions to the problem posed in the earlier model, but for now these solutions create other problems
    • "WAP servers", provide end-to-end security in a way because the data stream leaves the "WAP server" already encrypted with WTLS
  • 18. Proposed solution for the future
    • Pass Through Model of WAP system
    • [WAP device]--|[WAP gateway}---| [WAP Server] |  -----------------  |
    • WTLS
    • (Firewall) | |(Firewall)
  • 19. What is a proxy server?
    • A proxy-server plays the role of an agent between the web-browser or another web-client and the internet. With the help of a proxy-server users can use the internet in a controlled way, e.g. through a firewall.   
    • Furthermore, a proxy can be used as a filter (e.g. suppressing the referrer-header for security) or to cache documents. 
    • It is possible to create "off-line" caches and to index them for later searching. Because WAP Proxy-Server can also act as a web-server, it is possible to create virtual sites or to hide real sites
  • 20. References
    • Proxy servers- www checkcom.com/products
    • WAP faq’s –www.wirelessfaq.com
    • Ric Howell,Concise Group-WAP security
    • Architecture of WAP Gateway-http://weblog.cs.uiowa.edu/22C178f01/uploads/acct/ntang/architecture.html