server 2022 and fiddler classic

[alex]

hi there

on windows 2022 server when i close fiddler or stop capture traffic

running apps can nor connect tls 1.2

i always get errors for service connecting until start capturing.

What should I do to make the system work properly when the program is closed?

 

Thaks for your help :)

[alex]

Hello

As far as I understand, the problem is that SchUseStrongCrypto is used for the service. When Fiddler is running, the communication protocol communicates by mediating. When Fiddler is disabled, communication cannot be established. This problem was solved after the additions I made to the .NETFramework registry.

 

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

 

Thanks for your help.

[Nick Iliev]

Hello Alex,

 

By design, Fiddler does not preserve the proxy settings, and its address and port should be reverted once the capturing is turned off or the application is closed. Try the following:

- Once the application is closed, go to the OS proxy settings and ensure that the Fiddler proxy is removed from the manual proxy configuration. The default address and port for Fiddler Classis is 127.0.0.1:8866.

- Open a terminal and check if there is an active WinHTTP proxy through the following command:

netsh winhttp show proxy

In case you still see the Fiddler proxy, then you can reset it explicitly through the following command:

netsh winhttp reset proxy

 

Regards,
Nick Iliev
Progress Telerik

[alex]

Thank you for your answer

 

when Fiddler running

"Current WinHTTP proxy settings:

    Direct access (no proxy server). "

 

when stoped or closed

 

"Current WinHTTP proxy settings:

    Direct access (no proxy server)."

 

both same proxy. :(

[Nick Iliev]

That indicates that there is no direct WinHTTP proxy assigned, which means that the Fiddler settings are not present. Ensure that the settings are not present in the main OS proxy settings screen, and if the issue still persists, then check if the affected applications/services are not caching the proxy settings through some third-party logic.