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Anonymity of Proxys

Sep 19th, 2019
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  1. Anonymity of Proxy
  2.  
  3. The exchange of information in Internet is made by the "client - server" model. A client sends a request (what files he needs) and a server sends a reply (required files). For close cooperation (full understanding) between a client and a server the client sends additional information about itself: a version and a name of an operating system, configuration of a browser (including its name and version) etc. This information can be necessary for the server in order to know which web-page should be given (open) to the client. There are different variants of web-pages for different configurations of browsers. However, as long as web-pages do not usually depend on browsers, it makes sense to hide this information from the web-server.
  4.  
  5. What your browser transmits to a web-server:
  6. a name and a version of an operating system
  7. a name and a version of a browser
  8. configuration of a browser (display resolution, color depth, java / javascript support, ...)
  9. IP-address of a client
  10. Other information
  11.  
  12. The most important part of such information (and absolutely needless for a web-server) is information about IP-address. Using your IP it is possible to know about you the following:
  13. a country where you are from
  14. a city
  15. your provider?s name and e-mail
  16. your physical address
  17.  
  18. Information, transmitted by a client to a server is available (accessible) for a server as environment variables. Every information unit is a value of some variable. If any information unit is not transmitted, then corresponding variable will be empty (its value will be undetermined).
  19.  
  20. These are some environment variables:
  21.  
  22. REMOTE_ADDR ? IP address of a client
  23.  
  24. HTTP_VIA ? if it is not empty, then a proxy is used. Value is an address (or several addresses) of a proxy server, this variable is added by a proxy server itself if you use one.
  25.  
  26. HTTP_X_FORWARDED_FOR ? if it is not empty, then a proxy is used. Value is a real IP address of a client (your IP), this variable is also added by a proxy server if you use one.
  27.  
  28. HTTP_ACCEPT_LANGUAGE ? what language is used in browser (what language a page should be displayed in)
  29.  
  30. HTTP_USER_AGENT ? so called "a user?s agent". For all browsers this is Mozilla. Furthermore, browser?s name and version (e.g. MSIE 5.5) and an operating system (e.g. Windows 98) is also mentioned here.
  31.  
  32. HTTP_HOST ? is a web server?s name
  33.  
  34. This is a small part of environment variables. In fact there are much more of them (DOCUMENT_ROOT, HTTP_ACCEPT_ENCODING, HTTP_CACHE_CONTROL, HTTP_CONNECTION, SERVER_ADDR, SERVER_SOFTWARE, SERVER_PROTOCOL, ...). Their quantity can depend on settings of both a server and a client.
  35.  
  36. These are examples of variable values:
  37.  
  38. REMOTE_ADDR = 194.85.1.1
  39. HTTP_ACCEPT_LANGUAGE = ru
  40. HTTP_USER_AGENT = Mozilla/4.0 (compatible; MSIE 5.0; Windows 98)
  41. HTTP_HOST = www.webserver.ru
  42. HTTP_VIA = 194.85.1.1 (Squid/2.4.STABLE7)
  43. HTTP_X_FORWARDED_FOR = 194.115.5.5
  44.  
  45. Anonymity at work in Internet is determined by what environment variables "hide" from a web-server.
  46.  
  47. If a proxy server is not used, then environment variables look in the following way:
  48.  
  49. REMOTE_ADDR = your IP
  50. HTTP_VIA = not determined
  51. HTTP_X_FORWARDED_FOR = not determined
  52.  
  53. According to how environment variables "hided" by proxy servers, there are several types of proxies
  54. Transparent Proxies
  55.  
  56. They do not hide information about your IP address:
  57.  
  58. REMOTE_ADDR = proxy IP
  59. HTTP_VIA = proxy IP
  60. HTTP_X_FORWARDED_FOR = your IP
  61.  
  62. The function of such proxy servers is not the improvement of your anonymity in Internet. Their purpose is information cashing, organization of joint access to Internet of several computers, etc.
  63. Anonymous Proxies
  64.  
  65. All proxy servers, that hide a client?s IP address in any way are called anonymous proxies
  66.  
  67. Simple Anonymous Proxies
  68.  
  69. These proxy servers do not hide a fact that a proxy is used, however they replace your IP with its own:
  70. REMOTE_ADDR = proxy IP
  71. HTTP_VIA = proxy IP
  72. HTTP_X_FORWARDED_FOR = proxy IP
  73.  
  74. These proxies are the most widespread among other anonymous proxy servers.
  75.  
  76. Distorting Proxies
  77.  
  78. As well as simple anonymous proxy servers these proxies do not hide the fact that a proxy server is used. However a client?s IP address (your IP address) is replaced with another (arbitrary, random) IP:
  79.  
  80. REMOTE_ADDR = proxy IP
  81. HTTP_VIA = proxy IP
  82. HTTP_X_FORWARDED_FOR = random IP address
  83. High Anonymity Proxies
  84.  
  85. These proxy servers are also called "high anonymity proxy". In contrast to other types of anonymity proxy servers they hide a fact of using a proxy:
  86.  
  87. REMOTE_ADDR = proxy IP
  88. HTTP_VIA = not determined
  89. HTTP_X_FORWARDED_FOR = not determined
  90.  
  91. That means that values of variables are the same as if proxy is not used, with the exception of one very important thing ? proxy IP is used instead of your IP address.
  92. Summary
  93.  
  94. Depending on purposes there are transparent and anonymity proxies. However, remember, using proxy servers you hide only your IP from a web-server, but other information (about browser configuration) is accessible!
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