Hey,
since tonight (nothing changed on my Side I believe), randomly some Websites stopped to appear on Fiddler Everywhere MacOS in Capture Mode.
When I surf around / facebook / mmo-champion etc. (just example pages) they appear as Connect Tunnel opened but no content is seen.
So the Websites no longer get shown in the Traffic Window, just the Connect Tunnels.
I tried to uninstall Fiddler Everywhere, Resetting Configs by removing the Transprancy Proxy from MacOS but nothing seems to help, is there any instance I can check, why some websites randomly disappear and not coming back on MacOS?
Do I need to "listen" on more Ports or so?
1 Answer, 1 is accepted
Hello Feylin,
Thank you for providing the additional technical details about the servers trying to use the HTTP/3 protocol. We can confirm that HTTP/3 (H3) is not yet supported in Fiddler Everywhere, and as a result, you are not seeing any requests that use H3. The team is already researching the possibilities for supporting H3 proxying, and we are currently looking for the latest RFC related to the official support for proxies with H3.
Meanwhile, as a temporary workaround, you can explicitly strip the H3 support from the HTTP Response headers and force the servers to use HTTP/2 instead. This will allow you to see the traffic from pages like Facebook and mmo-champion through the FIddler's network capturing mode. You can create a rule that modifies the Alt-Svc response header. This header is used by servers to indicate that there is an alternative service that can load the experimental HTTP/3 resources.
A basic example would be to create a rule by using the "Update Response Header" action and update the value of the Alt-Svc header so that it does not contain h3 instructions. For example, the following shows the value of the Alt-Svc when accessing the mmo-champion landing page.
In the above case, you need to create a regular expression to remove the string value h3=":443" from the response header (so that the next requests to that server do not serve H3). Once the rule is active, you must reload the page (hard reset and clear cache) for the change to take effect.
Regards,
Nick Iliev
Progress Telerik
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On some Apps I see the connect Tunnel, but nothing else and it says: Traffic will be in there, but they not appear, I guess since the connect Tunnel switches to H3?
The Alt-Svc header is a response header sent from the server on the initial response (to "instruct" the client that the next requests can be made through H3), so there is no point in matching a CONNECT session. Note that during our test for a page like facebook.com to appear properly while capturing with Network capture, the rule needs to be active to match the Facebook UR, and then there should be an entirely new connection within the client (e.g., through "Hard Reset and Clear Cache" option in Chrome).
If you continue to see only a CONNECT session, then there is probably a different reason for the actual request and response not to show up. In that case, consider posting a private ticket where you can send us a SAZ archive so that we can continue the investigation further (without exposing your private data).
You can try with a rule similar to the following:
Is there any plan to caputre them in the future maybe with experimental Feature as well?
Last news I had was, that its hard for Telerik since you guys rely on some libaries? But maybe you can go in and try to add it :)
Imagine the power of UDP Traffic anylize as well.