Tracing HTTP Connections
By: Thomas Bayer
Date: 07/20/2009
Last Update:
This document describes how HTTP messages can be captured and analyzed using the Membrane Monitor tool.
To illustrate this we will trace the traffic to the homepage of predic8. But you can use any Web site, of course.
Download and Startup
After downloading we start the monitor by clicking on membrane-monitor.exe in the expanded archive.
Adding a Service Proxy
Membrane Monitor works as an HTTP proxy. Based on the configuration of service proxies HTTP messages are forwarded to their destinations. In this tutorial we will setup a proxy that receives requests on port 7000 and forwards them to their destination, the host predic8.com.
Figure 1:
Click on the Proxies menu and choose Add Proxy. Fill out the wizard step by step as shown in following screenshots.
Figure 2:
Select the Advanced Service Proxy and click on Next
Figure 3:
Figure 4:
Click on Finish at the last page of the wizard to complete the creation of the proxy.
Tracing HTTP Traffic
Now we can start tracing HTTP traffic. Open the following URL in Firefox, Microsoft IE or Google Chrome:
http://localhost:7000
Of course you can follow the link above. After requesting the URL you should see our homepage.
Figure 5:
Let's have a look at the monitor and see what was captured. Figure 4 shows a screenshot of the monitor. As you can see, four messages have been captured. An HTTP GET request to the resource / . The response of this request contains the HTML code of the Webpage. Inside this page there are two images and a referenced stylesheet.
Figure 6:
Now you can:
- Modify and resend messages
- Change HTTP headers
- Look at the raw messages
Or you can add custom behavior like:
- URL rewriting
- Logging
I hope you enjoy using the monitor.