I've been using Fiddler for years, but now, on Windows 7 (64 bit) I cannot get it to monitor traffic from IE 8.

With the Firefox add-on, it is able to monitor Firefox traffic with no problem.

This is not related to monitoring HTTPS traffic, or traffic to localhost.

I've tried running IE and/or Fiddler with "Run as Administrator", but no luck.

The best clue to the problem that I have is that in IE8, the "Local Area Network (LAN) Settings" dialog accessed from "LAN Settings" in the Internet Options / Connections tab is all grayed out.

I have two Windows 7, 64 bit computers, both on the same LAN. One works fine, the other has these settings grayed out, and a note on the Connections tab: "Some settings are managed by your system administrator". However, the system administrator has NOT set any.

Any ideas?

  • It seems to be something to do with the Group Policies in the Active Director, but we can't find any that are preventing this change. Jul 14, 2010 at 19:14

3 Answers 3


Turns out that an Active Directory Group Policy Object (GPO) was responsible for the problem.

In the Policy, it is under:

Computer Configuration
  Administrative Templates
    Windows Components
      Internet Explorer

and is called

Make proxy settings per-machine (rather than per-user)

If that setting is enabled, then Fiddler (Fiddler2) cannot adjust the proxy settings on the local computer when it starts.

After making that change on the server, all users will eventually get the new setting. To get the new setting immediately, run this command on any computer:

gpupdate /target:Computer /wait:0

Here is a temporary solution:

  1. Run IE as an administrator
  2. Tools > Internet Options > Connections > LAN Settings
  3. Check "Use a proxy server for your LAN ..."
  4. Address: add localhost
  5. Port: add 8888

Fiddler seems to use this port, and the reason Fiddler can't capture the traffic is that IE by default is using a different port.

  • I'd still like to be able to run it without being Admin. Jul 14, 2010 at 18:25

Just wanted to add for people with windows 7 home editions, that don't have the group policy editor:

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\CurrentVersion\Internet Settings]

For other group policy settings: http://www.microsoft.com/en-us/download/details.aspx?id=25250

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