Configuring Fiddler to use company network's proxy?

Question

I'm trying to get Fiddler to work with my company's proxy. Every external request is returning 407.

So far I've tried adding oSession.oRequest["Proxy-Authorization"] = "YOURCREDENTIALS"; to the customized rules where I used my USERNAME:PASSWORD in base64. Still no luck.

Any ideas? Thanks.

Answer 1

Note: There is an answer with a higher voting available. Because of SO sorting it is below the accepted answer.

I had the same problem, too, and solved it like this:

1. Started Fiddler with it's standard configuration.
2. Started IE and made a HTTP-request to an external web-site.
3. The proxy authorization dialogue popped up, where I entered my credentials.
4. In Fiddler searched the request headers for "Proxy-Authorization".
5. Copied the header value which looked like "Basic sOMeBASE64eNCODEdSTRING=" to the clipboard.

6. Altered the CustomRules.js with the following line within OnBeforeRequest:

   oSession.oRequest["Proxy-Authorization"] = "Basic sOMeBASE64eNCODEdSTRING=";

So my approach was quite similar to yours just that in advance I checked what kind of proxy authorization the server required by using Fiddler to debug the authorization header. That way I found out I had to add "Basic" before the Base64 encoded credentials and I didn't even have to use the tool to encode the credentials to Base64. Just copied the value from the proxy authorization header.