Detecting HTTP client used with HTTP Server ?

Question

Hi all,

I used the same request with 2 differents client HTTP. One is accepted by server (java request in IE) and not the other (Indy Client in Delphi software) ? Is there a way to detect the request difference between the two request ?

Is there a way to hide I use Indy ?

Best regards

Answer 1

You must be talking about User-Agent. I'm not sure how you set it in Indy but the User-Agent HTTP header identifies which client is used, so you can set it to pretend you're IE or another browser.

Also, try using an HTTP sniffer (Scoop is a good one on OSX) to see exactly what headers are being sent to make sure you behave exactly like the browser.

Answer 2

wireshark/tcpdump is your friend in most situations when there is a need to analyse http requests.

With tcpdump you can record the request on the server, and then analyse the captured data in wireshark.

Answer 3

I think you are best of with Paros. http://www.parosproxy.org/

It will allow you to monitor, pause and customize the HTTP request on-the-fly. It's a hacker tool, but you'll love it.

Answer 4

UserAgent is under the Request property. By default, Indy's user agent string is "Mozilla/3.0 (compatible; Indy Library)". Change it to a current string used by FireFox, IE or other recognized browser.

You can find examples on the UserAgentString site.

There are more details in the Indy KB PDF.

Answer 5

I recommend Fiddler2, which inserts itself as a proxy, and will record all http/https traffic, with nice inspectors. http://www.fiddlertool.com/fiddler2/version.asp

Answer 6

Don's Proxy is a nice free tool to capture HTTP requests. As you write that you are using Java, I assume that the JRE required for this tool is installed already.

Then compare the two requests using TortoiseMerge or some other diff utility.

Answer 7

I finally use TidTCPClient and made my POST request by hand and it works now (it's a long time allready).

I still not understand why but I have no time to look after this.