Proxy Servers Information

Hi there, experts!

I have three questions regarding proxy servers, they are all related and I'm giving 500 points to the person who answers correctly.

Overview:
I would like to know if there is any way and how to find out detailed information about a Proxy Server.

For instance, if you go to www.proxy4free.com/page1.html, you will see a list of proxy servers with  extra information such as the "type" of server. How can a program scan a server to see if it is "transparent", "anonymous", "high anonymity", etc.?

Specific questions:
Can I use Winsock to obtain this information?
How can I know which port I have to use to connect to the Proxy Server?
How can I know if the IP address that I'm pinging or connecting to is actually a Proxy Server?

Thanks!


NoviceASPAsked:
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HoweverCommaCommented:
Here are the different proxies and the properties.

Transparent Proxies
They do not hide information about your IP address:

REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = 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 IP
HTTP_X_FORWARDED_FOR = 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 IP
HTTP_X_FORWARDED_FOR = random IP address

High Anonymity 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_FOR = not determined

>>Can I Use winsock to obtain this information?
Well you need to access a remote system and see what info is available in the packets.

Why not use any of the free checkers out there?
http://www.all-nettools.com/toolbox
http://www.stayinvisible.com/index.pl/proxy_list
You could use your own web server if you have one to check the variables described above.

>>How can I know which port I have to use to connect to the Proxy Server?
Generally it will be supplied to you with the proxy address, if not 8080,3128 & 80 are common ports.
The port is set in the proxy config and can be anything this is the problem with open proxies admins just too dumb to know or too lazy to change them.

>>How can I know if the IP address that I'm pinging or connecting to is actually a Proxy Server?
From a simple ping you can not tell, a ping gets a reply from a server. It does not reveal any information about HTTP/FTP/PROXY services etc.
You can simply attempt a proxy request by supplying any ports dicovered as a proxy to the winsock control and attempt to access a site with the proxy active.
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NoviceASPAuthor Commented:
Your explanation was good enough to clarify my doubts and answer my questions.
Thanks a lot!
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