Disable fiddler as system proxy

8 posts, 0 answers
  1. Dwight
    Dwight avatar
    1 posts
    Member since:
    Mar 2017

    Posted 30 Mar 2017 Link to this post

    I have one specific browser instance that I have configured to always use fiddler, I turn on and off others as needed.   I'm doing development work and I want to see what's actually being sent back and forth, but, I really only care about my stuff.

    I launch fiddler with my PC, and I have the "Capture traffic" turned off and the setting "Act as system proxy on startup" is not checked in the connections tab.

    Other application on my system are still finding and using fiddler as it's proxy server, frequently causing failures.

    How do I "hide" fiddler so that other systems like skype and google drive don't use it?   

    It impacts me negatively in 3 ways. 

    First, I only want to see traffic that I send to fiddler, I have to go out and delete a bunch of stuff.  I can remove them with filters and probably find a way to make my filters "stick" and survive reboot.   I'd have to research that.

    Second and more importantly, I decrypt https, which fails on application that are not configured to use the self generated signatures.

    Third, when I do shut down fiddler, the apps that have auto-detected it and configured themselves to use fiddler, still want to use fiddler.

  2. Tsviatko Yovtchev
    Admin
    Tsviatko Yovtchev avatar
    549 posts

    Posted 04 Apr 2017 Link to this post

    Hi,

    When Fiddler is capturing traffic it sets itself as the WINInet proxy system wide. Any app that uses WINInet proxy settings will redirect its traffic through Fiddler in that case. When it shuts down it should restore the original proxy settings so the apps should switch back to not using FIddler as a proxy. Now an app might not keep an eye on WINInet proxy changes and that might explain part of what you see. The Act as System Proxy on startup setting though should work. Are you sure Fiddler still starts capturing traffic with that off? What is in your proxy settings at that moment?

    Regards,
    Tsviatko Yovtchev
    Telerik by Progress
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  3. TJ
    TJ avatar
    1 posts
    Member since:
    Aug 2017

    Posted 14 Aug 2017 in reply to Tsviatko Yovtchev Link to this post

    Tsviatko,

    I am new Fiddler user.

    Basically, I do not think Fiddler automatically restores the original proxy settings.  I had to completely uninstall Fiddler due to ALL browsers on my computer (IE, Chrome, and Firefox) received an error of "proxy server isn’t responding" or something along those lines.  For me to reach the Internet, I removed Fiddler and rebooted my PC.  

     

    Is there a setting or registry entry I should check/change to ensure Fiddler restores the original proxy settings when I shutdown Fiddler?

     

    T.J.

  4. Alexander
    Admin
    Alexander avatar
    336 posts

    Posted 17 Aug 2017 Link to this post

    Hi,

    No, there is no such setting. If Fiddler has "Act as system proxy at startup" enabled, it should restore the original proxy settings on shutdown automatically.

    You can check the current proxy settings by going to "Internet Options -> Connections -> LAN settings". If the "Use a proxy server for your LAN" setting is checked, in "Advanced" the proxy address is set to 127.0.0.1 and the port is set to the port Fiddler is listening at (the default is 8888), then Fiddler is set as proxy. You can easily stop it from being proxy by unchecking the "Use a proxy server for your LAN" setting or by changing the address/port combination (if you are using proxy server). There is no need to restart your PC or to remove Fiddler.

    Regards,
    Alexander
    Progress Telerik
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  5. Steven
    Steven avatar
    1 posts
    Member since:
    Jan 2018

    Posted 03 Jan in reply to Alexander Link to this post

    Hi. When the proxy setting is altered my site no longer responds and all internet connection is no longer valid on all browsers and i get an error pop up on the page. See attached, is there a way around this issue.  

    Regards 
    S

  6. Suresh
    Suresh avatar
    1 posts
    Member since:
    Mar 2018

    Posted 13 Mar Link to this post

    Hi, This is Suresh. When Fiddler setting up it's own proxy application not loading on IE and if I uncheck the proxy settings Fiddler not capturing the traffic. Please suggest if any workaround.
  7. Pieter
    Pieter avatar
    1 posts
    Member since:
    Mar 2011

    Posted 19 Jul Link to this post

    Telerik resets the automatic set script for me. We don't use the manual proxy server setting so I cannot say whether that gets reset.

    I have a slightly different problem where my internet stop working after a while and I have to manually reset the settings and click the yellow bar in Fiddler.

  8. Alexander
    Admin
    Alexander avatar
    336 posts

    Posted 23 Jul Link to this post

    Hello Pieter,

    Which yellow bar in Fiddler you have to click (since there are several)? I assume you are talking about the "The system proxy was changed. Click to reenable capturing." one. If you are talking about this one, then some other software (VPN, AV) is changing the proxy settings of the machine.

    Regards,
    Alexander
    Progress Telerik
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