|
|
 |
 |
What is proxy? |
 |
| |
|
|
|
Proxy server (shortly - proxy) is a computer program that is activated on connection to a certain port of a computer (they
also
say
it "bind" to certain port). As any other computer program it has many settings which allow it to disable access to certain places,
cut off adverts etc.
What proxy can
While using GET/POST method (regular surfing the web):
* disable access to certain sites, like www.porno.com or www.icq.com;
* disable access to sites, containing banned keywords, like "porno" or even "proxy";
* cut off certain parts on pages (banners);
* disable receiving of files with predefined extensions (*.mp3, *.zip, *.exe, *.rar etc.) and/or predefined sizes (both in Kbs
and/or in pixels, for example - 468x60);
* log web surfing activity and send report to system administrator with all web pages visited;
* disable use of any protocols (for example, disable access to "https://..." and/or "ftp://..." sites);
* disable access from any computers to this proxy. In other words it is quite possible that of two near by computers one may work
with proxy and another may not;
While using CONNECT method (visiting "https://..." sites, building proxy chains, port mapping through proxy etc.) or using SOCKS
proxy:
* completely disable CONNECT method (or turn off SOCKS proxy). Then ICQ will not work and there will be no access to
"https://..." sites;
* disable connection through proxy to certain servers, for example, login.icq.com;
* disable connection through proxy to certain ports, for example, port 25 (SMTP), port 6667 (IRC), port 5190 (ICQ);
* disable connection through proxy to all ports except specified, for example, port 443. In this case proxy names "HTTPS
proxy";
What proxy cannot
* use heuristic analyzer, i.e. make semantic analysis of page contents and disable all sites with certain materials, despite the
keywords;
* filter information, for example, block some pages using keywords while using CONNECT method (or in SOCKS proxy);
* let pass back connections from internet (SOCKS 5 can do it but this is also non-trivial task);
Resume: proxy server is a computer program, so as any program it has its own merits and demerits. If administrator tuned a proxy and
forgot about it then proxy server always can be bypassed. Otherwise, your attempts to bypass proxy server are always a battle with
sys admin and all your solutions are temporary - until administrator find and close just another "hole".
They are types of proxy:
Transparent Proxies
They do not hide information about your IP address:
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy name or IP
HTTP_X_FORWARDED or HTTP_X_FORWARDED_FOR or HTTP_CLIENT_IP = your IP
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.
Anonymous Proxies
All proxy servers, that hide a client's IP address in any way are called anonymous proxies
Simple Anonymous Proxies
These proxy servers do not hide a fact that a proxy is used, however they replace your IP with its own:
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy name or IP
HTTP_X_FORWARDED or HTTP_X_FORWARDED_FOR or HTTP_CLIENT_IP = proxy IP
These proxies are the most widespread among other anonymous proxy servers.
Distorting Proxies
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:
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy name or IP
HTTP_X_FORWARDED or HTTP_X_FORWARDED_FOR or HTTP_CLIENT_IP = random IP address
High Anonymity (Elite) Proxies
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:
REMOTE_ADDR = proxy IP
HTTP_VIA = not determined
HTTP_X_FORWARDED and HTTP_X_FORWARDED_FOR and HTTP_CLIENT_IP = not determined
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.
Source: www.freeproxy.ru
|
|
|
 |
|
 |
|
