Hi people
I was reading tutorials on proxy and I configured my Firefox with free IP proxy. I'm wondering. Is it really true that browsing and doing stuff under proxy I am 100% anonymous? I cannot be detected right? If that's case why hackers don't use when they're gathering information about their target? I mean I read pages and tutorials about hacking (ethical beginner) and they don't really mention using proxy. When hackers get caught they get caught by their IP right? so Why didn't they use proxy servers instead? Bottomline what are the drawbacks of using proxy, it must be something behind it.

From the target's perspective, the spice of the connection is te proxy. You are anonymous up to that point. You are not anonymous from the proxy's perspective.

Whether or not you are being logged or whatever other action is being taken at that proxy is controlled by whoever manages the proxy.

Depends on what are you doing. First of all, for ethical hacking you have authorization to do what you're doing so you don't need to protect your IP or being anonymous.

For other kinds of activities, depends how serious is what you do to know if they are going to find you. Most new proxy servers saves a log of each IP and requests and a lot of them(transparent proxies) show your real IP to the other side. But for anonymous new proxies, if something really bad happens they could force them to show the logs and then find your IP.

You can test yourself all this by using any working new proxies and verify against your own web server to see what headers are visible and what not. If you don't have a web server, just install an Apache or any other in your PC and test against them.

commented: nice answer +0

toseo You said

verify against your own web server to see what headers are visible and what not

I have Apache 'localhost' server configured. How do I verify against the Apache to see if my real IP appears? I know that if for example I send an e-mail using one of these proxies than in the recieved e-amil's header I can verify, but How do I verify it with my own webserver?

My OP is Ubuntu 12.04

You can use a web server (Apache, IIS, etc...) to either log the traffic, or just develop a page either using PHP, ASP, ASP.NET or any other server side scripting language that can detect the remote IP and display it on the page.