I have Windows 8.1 installed on my computer and regularly use Fiddler to capture web traffic.
Recently, however, when I open Fiddler and
it strats to capture web traffic, my Internet connectivity dies.
The error I get when I open IE is "the proxy server isn't responding."
In Chrome, I get "Could not connect to proxy server" with the following error: "Error code: ERR_PROXY_CONNECTION_FAILED."
Fiddler doesn't even capture any of the requests going out. The weird thing is that Fiddler was working ok just some days ago and nothing was recently installed on my system.
Searching the Internet for 5 hours, trying everything, and no effective response.
This also had no effect: http://www.telerik.com/blogs/fiddler-and-internet-explorer-11-on-windows-8-1
It seems that the proxy server created by Fiddler is simply not attending to any traffic.
If I close Fiddler or disable the capture mode my internet come back to normal.
Uninstall and reinstall Fiddler does not solve the problem, neither restart Windows.
This question has some similarities with my problem, but as I said, none of the answers worked for me.
Why is Fiddler having this problem, and how can I fix it?
99% of the time, this is caused by running a 3rd-party firewall which is blocking access to Fiddler.
1% of the time, this is caused by plugging a Windows Phone device into your PC over USB. The Windows Phone team steals Fiddler's default port (8888) from it.
Running Help > Troubleshoot and updating your question with its output may help.
Related
I use a local Python web server on my Windows machine. It’s simple, but good enough while in the static web page development stage. I just run it with something like this on my WSL command line:
python3 -m http.server
I can also access it on mobile devices on the same network, by going to my local address, e.g.: http://192.168.1.12:8000. All was good, until suddenly I could no longer access it on external devices, I got a “server not responding” type of message. Also, I could clearly see that when I refreshed the page on my phone, there was no GET request on the logs.
Immediately I tested on the local machine, and it was still working fine. This obviously smelled like a Firewall. In Linux, I’d know what to do, but it’s the first time I had to deal with this on Windows. This is what I’ve tried, without resolving the connection problem:
I opened the Event Viewer but could not see any obvious logs to check
I stopped the server (CTRL+C) and started it again on another port (5000). The Windows Firewall message popped up again asking for permission for Python3 to access the “Public network” and the “Private network”. Normally I just tick the “private network” but this time I checked both, as a troubleshooting step, in case my Wi-Fi was incorrectly being considered “public”.
I went to Windows Firewall and temporarily shut it down on the private network.
I installed and tried running nmap on the WSL, but it failed to run and prompted me to install the Windows version instead.
I installed and ran the Windows version of nmap but it told me that port 5000 was open.
What is the recommended way to troubleshoot and fix this issue?
Still suspecting the firewall, I tried something new, I switched off the “public network” firewall. I tested on my mobile and the page loaded as normal again! I immediately turned the firewall back on. Tested the page on my mobile once more, still fine. So, the solution was to toggle the public network firewall. I would make it more generic and toggle all firewall categories on Windows. And of course, I would make sure that the firewall stays on, this was a very quick operation.
I thought I’d put this here rather than ServerFault or SuperUser as it could potentially be more useful to developers, and it took a precious hour of my time. I still don’t know why it stopped working on its own in the first place. Better troubleshooting steps or suggestions are welcome, but I probably won’t be able to verify it as I don’t know how to purposely induce the issue.
Another solution that worked another time, was to delete all instances of Python 3.8 from the list of allowed apps (I don't know why Windows shows the same app multiple times) then (re)start the Python server and allow it through when the Firewall question pops up again.
In windows firewall you may have 4 options to configure your local web server when you are creating new Inbound connections rule.
1 Program
2 Port
3 Predefined
4 Custom
Try to use port only in "TCP protocol" and the custom port.
Allow connection.
Select: all checks: domain, private and public.
Enter a name.
Thats all.
While trying to start an asp.net 5 kestrel website, I sometime got this error :
Failed to bind to address http://localhost:5000
"An attempt was made to access a socket in a way forbidden by its access permissions."
The only way to solve the issue is to reboot the computer.
The port (5000) is not in use in TCPView or NETSTAT.
I tried to explicitly allow the app in the windows firewall, but no luck either. Same with fully deactivating the firewall.
I got this issue with a published website (kestrel) without any visual studio, and also in debug from VS2019.
My customers also have the issue around 1 day in a month, without any apparent reason.
Do you have any idea to help me track down this issue ?
Thanks.
I am following this instruction http://docs.telerik.com/fiddler/Configure-Fiddler/Tasks/ConfigureForiOS. Everything works until section Set the iOS Device Proxy.
Once I set the proxy on my iPhone, I can't connect to the internet from the phone anymore. Not even accessing the echo page, which I could access before turning on the proxy on the phone. I already installed the root cert on my phone, the makecert add-on on Fiddler
Could someone help with ideas to diagnose the issue here? Thanks,
What might be stopping your iphone from reaching your Fiddler machine on the port specified, usually 8888?
Have you a firewall on the Fiddler machine? You might need to open
the port.
Does your LAN have an automatic redirect to a login page? Ours
does, so I have to disable the proxy on the iphone while I login,
then reenable it.
Does your LAN expose the IPs of cable-connected machines to WIFI
users? Not all do.
Can you browse a simple web page on your Fiddler machine from your
iphone, before starting fiddler or doing any proxy configuration?
You might need to get really serious and install a ping utility on the iphone.
I am experiencing a strange issue with connecting to my web server from my Iphone4.
I have an app that connects to my web serer and downloads a chunk of JSON. This works fine when i'm connected via WIFI, but fails through 3G. I don't think it's my app, as Safari also fails to retrieve any page on my web server when using 3G.
My web server has a fixed i.p and is running apache/Centos pretty fresh out of the box, I have not messed with the firewall or iptables settings.
The error obtained from the iphone is "The network connection was lost"
It feels like a firewall issue, but i have not explicitly denied any ips. Is there some aspect of a 3g connection that gets denied by default on Linux?
I realise this is all vague at this time, but does anyone have any wisdom to offer?
Many thanks in advance.
Here is a topic related to iphone connection loss through 3G cellular data whereas WiFi works fine, also giving the error "The network connection was lost"
Couple suggestions:
Ensure that your web server is
responding in a timely fashion. If
it is taking a little too much time,
the 3g connection might give up.
Check your web server logs and see if the connection is reaching
your web server at all, and if any
errors are being recorded. If so,
investigate.
There isn't anything special about a 3g connection wrt you web server. Only difference would be that it is less reliable or slower.
How are you actually trying to connect to your web server? When its over wifi you are local on your network and the name of the server will probably work. But when its over 3g its on the interwebs and will probably not respond to the name of the server.
I asked a very similar question not too long ago and got some great responses. I've made it pretty far but still can't quite get things to talk. What I have is a PC running IIS and a web service inside of that. I'm trying to get the iPhone simulator on my Mac to be able to see this web service. I can ping my PCs local IP address from the Mac just fine, it's clearly alive and on the network. However, no matter what URL I enter into Safari the web service will not appear.
Any suggestions?
Thank you very much in advance.
Is this a web service or web application?
One fair possibility is that your Windows firewall could be blocking access to port 80. If it is, open your Windows firewall settings and add an exception for port 80 (Control Panel -> Windows Firewall -> Exceptions).
You might try using telnet on your Mac to test connecting to the web service/application.