Hello, 

I am attempting to capture traffic to troubleshoot an ongoing issue, however I cannot get FiddlerCap to work with the Edge browser.  When I start a capture I get the message "Can't connect to proxy server."  This only happens while Fiddler is running.  If I stop the capture, I have no issues getting to the internet.  I'll attach some files to show my settings.  Thank you so much for your guidance!

-Kerry

I'm working on bunch of projects, all on .net Core 2.0 / Standard 2.0, that require making Web Services calls. WS calls are made through proxy generated from a Connected Service reference. I've been working on these projects for an year+ and have been using Fiddler regularly. I'm on Windows 10, VS 2017, latest version of Fiddler 5.0.20181.14850.

I don't know exactly what changed recently (there were OS updates, VS updates, etc). But, WS traffic is no longer captured in Fiddler. Anything else to HTTP/HTTPs endpoints are captured. Even if I make a call to the WS endpoints with just a HTTP WebClient class, from code, it shows up in Fiddler. This is true to .NET Core Web API projects, Console app projects and XUnit Test classes.

I might be able to resolve this by pointing the code to the Fiddler proxy. But, given that this has worked for so long, I want to understand what happened and possible resolve it without going the proxy path.

Any ideas would be appreciated.

Thanks

I have a console app that communicates with a number of 3rd party services via http. The original version of the app is developed for the .net Framework and Fiddler is able to successfully all of the https calls that the app makes.

I have ported the app to .Net Core 2.1. Fiddler is not capturing the HTTPS calls made by the .Net Core version of the app.

Any ideas as to why Fiddler is not working with the .Net Core app?

 

Hi Eric,

Thanks for the fiddler tool.

Actually i want to automatically export fiddler data to my pc  and i don't know how to do this.

So i request you to please help me in this.

 

 

Regards

Anshu

How can i use a upstream proxy conditionally according response header content length?

Thanks!

Regards everybody... i have a program here made by my friend to help me with some games (it's almost a cheat) but he has a hwid lock in it, but i would like to see where the info goes to... the problem is: his software, everytime that detects the word "fiddler" or other programs like this, closes. How could i hide the Fiddler from that? I really need to see it... thanks from now

     We have a Windows Server 2008 R2 that hosts an ASP.Net Web API. This Web API makes a series of 3 calls to a SOAP Web Service running in a different ASP.Net application on the same server.

One of our developers installed Fiddler on the server to debug the calls from the Web API to the Web Service.

After debugging and uninstalling Fiddler v5.0.20182.28034 for .NET 4.6.1, calls from the Web API are still being directed to the 127.0.0.1:8888 proxy address.

We have reinstalled Fiddler and started and Stopped it gracefully to be sure the Internet Options are being set back. 

We have searched the Web API application directory and its Web.config file for a defaultProxy setting.

We have searched the entire Microsoft.Net directory in Windows and all machine.config and Web.config (even *.config) files for any defaultProxy setting and have found only '<proxy usesystemdefault="true" />' yet after repeated reboots and install/uninstall of Fiddler, we cannot get the Web API to work without Fiddler installed and running on the server.

As soon as we shut Fiddler down, the Web API calls to the Web Service begin to fail with the error "...target machine actively refused it 127.0.0.1:8888"

Can you help me determine what is happening?

Thanks in advance.

Hi

trying to monitor my phone traffic via a fiddler running in windows EC2 machine.

I setup Fiddler on a windows machine in EC2, I have enabled allow remote connection and I have open port 8888 on windows firewall and AWS firewall.

I point my phone network proxy to public IP for that machine and the right port.

When I open ://<public ip>:8888 on the phone, it never returned with the Fiddler echo page.

I noticed that in Fiddler there is a traffic coming in but it never complete and seems duplicated (loop).

I suspect that the fiddler echo page  listen to the public and only private IPs.

Can someone guide me where can I change that setting or what step have I missed?

Hello,

I host remote FiddlerCore instance for remote debugging/etc. Obviously this is a bad idea, but I am trying to lockdown my instance from unauthorized users as an open proxy.

 

Ideally it would be through firewall/iptables, but since ip changes it is not very useful to me.

 

I would like to add proxy authentication, but iOS does not send "proxy-authorization"/"proxy-authentication" header, instead a proxy authentication challenge must be presented.

Is this possible with FiddlerCore? Any other tips for locking down this instance?

First of all, thanks a lot for this amazing framework. I have developed a small tool (c#) to intercept requests to a server and give them a local response using the LoadResponseFromFile method. This works nicely with both HTTP and HTTPS requests. Though, with HTTPS, I would have to let the first request pass to the server. I want to make it so that the tool would do without that. From my basic understanding, if I am not wrong, this has something to do with the original handshake. All subsequent requests can be handled without fuss.

Now, I went to the Fiddler tool and tries to trace this. The request that I cannot seem to handle, i.e. the first request, is displayed as:

200 HTTP Tunnel To x.x.x:443

where x.x.x is the server. The body size is 0. On Raw tab, I get:

HTTP/1.1 200 Connection Established

and some lines under it, Encrypted HTTPS traffic flows through this CONNECT tunnel. HTTPS Decryption is enabled in Fiddler, so decrypted sessions running in this tunnel will be shown in the Web Sessions list plus some other data.

Can you guide me in the right direction on how to handle those requests locally without having to rely on the server?

 

Regards and thanks.