How to use Fiddler to monitor WCF service

Question

I have a WCF service that accepts a  complex type and returns some data  I want to use Fiddler to see what the incoming requests to the service looks like  The client is  net console app which uses a Service reference proxy  Is this possible with Fiddler  I m new to this tool and have only used it in the past to post data with the request builder

User · Answer

This is straightforward if you have control over the client that is sending the communications. All you need to do is set the HttpProxy on the client-side service class.

I did this, for example, to trace a web service client running on a smartphone. I set the proxy on that client-side connection to the IP/port of Fiddler, which was running on a PC on the network. The smartphone app then sent all of its outgoing communication to the web service, through Fiddler.

This worked perfectly.

If your client is a WCF client, then see this Q&A for how to set the proxy.

Even if you don't have the ability to modify the code of the client-side app, you may be able to set the proxy administratively, depending on the webservices stack your client uses.

User · Answer

Standard WCF Tracing Diagnostics  If for some reason you are unable to get Fiddler to work  or would rather log the requests another way  another option is to use the standard WCF tracing functionality  This will produce a file that has a nice viewer   Docs  See https   docs microsoft com en-us dotnet framework wcf samples tracing-and-message-logging  Configuration  Add the following to your config  make sure c  logs exists  rebuild  and make requests      lt system serviceModel gt       lt diagnostics gt         lt  -- Enable Message Logging here  -- gt         lt  -- log all messages received or sent at the transport or service model levels -- gt         lt messageLogging logEntireMessage  true                        maxMessagesToLog  300                        logMessagesAtServiceLevel  true                        logMalformedMessages  true                        logMessagesAtTransportLevel  true    gt       lt  diagnostics gt     lt  system serviceModel gt      lt system diagnostics gt       lt sources gt         lt source name  System ServiceModel  switchValue  Information ActivityTracing          propagateActivity  true  gt           lt listeners gt             lt add name  xml    gt           lt  listeners gt         lt  source gt         lt source name  System ServiceModel MessageLogging  gt           lt listeners gt             lt add name  xml    gt           lt  listeners gt         lt  source gt       lt  sources gt       lt sharedListeners gt         lt add initializeData  C  logs TracingAndLogging-client svclog  type  System Diagnostics XmlWriterTraceListener          name  xml    gt       lt  sharedListeners gt       lt trace autoflush  true    gt     lt  system diagnostics gt

User · Answer

Consolidating the caveats mentioned in comments answers for several use cases   Mostly  see http   docs telerik com fiddler Configure-Fiddler Tasks ConfigureDotNETApp   Start Fiddler before your app In a console app  you might not need to specify the proxyaddress    lt proxy bypassonlocal  False  usesystemdefault  True    gt   In a web application   something hosted in IIS  you need to add the proxyaddress    lt proxy bypassonlocal  False  usesystemdefault  True  proxyaddress  http   127 0 0 1 8888    gt   When  NET makes a request  through a service client or HttpWebRequest  etc  it will always bypass the Fiddler proxy for URLs containing localhost  so you must use an alias like the machine name or make up something in your  hosts  file  which is why something like localhost fiddler or http   HOSTNAME works  If you specify the proxyaddress  you must remove it from your config if Fiddler isn t on  or any requests your app makes will throw an exception like      No connection could be made because the target machine actively refused it 127 0 0 1 8888  Don t forget to use config transformations to remove the proxy section in production

User · Answer

I just tried the first answer from Brad Rem and came to this setting in the web config under BasicHttpBinding    lt system serviceModel gt       lt bindings gt         lt basicHttpBinding gt           lt binding bypassProxyOnLocal  False  useDefaultWebProxy  false  proxyAddress  http   127 0 0 1 8888                         lt  basicHttpBinding gt       lt  bindings gt           lt system serviceModel gt    Hope this helps someone

User · Answer

So simple  all you need is to change the address in the config client  instead of  localhost  change to the machine name or IP

User · Answer

Fiddler listens to outbound requests rather than inbound requests so you re not going to be able to monitor all the requests coming in to your service by using Fiddler   The best you re going to get with Fiddler is the ability to see all of the requests as they are generated by your Console App  assuming that the app generates web requests rather than using some other pipeline    If you want a tool that is more powerful  but more difficult to use  that will allow you to monitor ALL incoming requests  you should check out WireShark   Edit  I stand corrected  Thanks to Eric Law for posting the directions to configuring Fiddler to be a reverse proxy

User · Answer

You need to add this in your web config   lt system net gt     lt defaultProxy gt       lt proxy bypassonlocal  False  usesystemdefault  True  proxyaddress  http   127 0 0 1 8888    gt     lt  defaultProxy gt   lt  system net gt     then Start Fiddler on the WEBSERVER machine   Click Tools   Fiddler Options    Connections    adjust the port as 8888  allow remote if you need that  Ok  then from file menu  capture the traffic    That s all  but don t forget to remove the web config lines after closing the fiddler  because if you don t it will make an error   Reference   http   fiddler2 com documentation Configure-Fiddler Tasks UseFiddlerAsReverseProxy

User · Answer

Just had this problem  what worked for me was to use localhost fiddler     lt endpoint address  http   localhost fiddler test test svc              binding  basicHttpBinding               bindingConfiguration  customBinding               contract  test               name  customBinding   gt

User · Answer

I have used wire shark tool for monitoring service calls from silver light app in browser to service  try the link gives clear info  It enables you to monitor the whole request and response contents

User · Answer

You can use the Free version of HTTP Debugger   It is not a proxy and you needn t make any changes in web config   Also  it can show both  incoming and outgoing HTTP requests  HTTP Debugger Free

[wcf] How to use Fiddler to monitor WCF service

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