Wednesday, November 5, 2014

Using FiddlerCore on Remote devices

Some time back, I wrote a blog on FiddlerCore
I had created a windows application using FiddlerCore and was interested in using it on remote devices like WindowsPhone/iOS/Android/etc
After some investigations, I was able to achieve this goal by doing the following:

Create Fiddler Root certificate using CertMaker.dll and BCMakeCert.dll

CertMaker.dll uses the BouncyCastle C# library (BCMakeCert.dll) to generate new certificates which are compatible with iOS devices.
Make sure these dlls are in the folder where your executable and FiddlerCore.dll live.
The root certificate is created in the below method
public void MakeCert()
            if (!CertMaker.rootCertExists())
                if (!CertMaker.createRootCert())
                    throw new Exception("Unable to create cert for FiddlerCore.");
                    Logger.Log("Created Fiddler Root Cert for Https Inspection");
            X509Store certStore = new X509Store(StoreName.Root,StoreLocation.LocalMachine);

Start Fiddler Application on a well-known port

Start Fiddler Application on a well-known port which will allow inbound connections e.g. 9999
FiddlerApplication.Startup(9999, FiddlerCoreStartupFlags.Default);

Use FiddlerCoreStartupFlags.Default

Start FiddlerApplication with FiddlerCoreStartupFlags.Default. This will ensure that remote connections are allowed and https decryption is enabled
FiddlerApplication.Startup(9999, FiddlerCoreStartupFlags.Default);

Enable Echo Service

Echo service needs to be enabled so that the root certificate can be downloaded and installed on the remote devices for https inspection. This is done by setting the below preference
FiddlerApplication.Prefs.SetBoolPref("fiddler.echoservice.enabled", true); 

Configure proxy on Remote devices

1.       On the remote device, go to http://<local machine IP>:9999 and download and install the Fiddler Root certificate
2.       On the remote device, go to network settings and add/change the proxy to local machine IP and port 9999
3.       Now you will be able to dogfood new stuff on the remote device and view metrics/logs on the local windows machine.
 Once the above steps are done, everything else is similar to what’s described in


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