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1 answer
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I want to use AutoResponder to mock a response from my server. The response in question is JSON object and I need to tweak its properties slightly. The thing is I cannot seem to do that via the Edit Response menu in Fiddler. Here's a screenshot: http://screencast.com/t/1f7iNWTF1NX9

There's something called "Send to TextWizard" but I don't know what that's about.

Thanks
Nick Iliev
Telerik team
 answered on 03 May 2021
1 answer
191 views
How to cancel the highlighted?
I'm afraid the software of progress telerik fiddler web debugger does not have this capability.
Nick Iliev
Telerik team
 answered on 03 May 2021
2 answers
337 views

https://docs.telerik.com/fiddler/knowledge-base/fiddlerscript/modifyrequestorresponse?_ga=2.226810973.1912327690.1619085606-390831375.1615941114

 

I reviewed the content on this link. I added the nuget library. Why can't I use these codes? When using it with C #, I get an error as I mentioned in the appendix. "'oSession' does not exist in the current context" What is the cause of this error? I cannot use any code related to Fiddler. What causes the oSession error? I want to work on FiddlerCore, but I couldn't find a solution for this error.

Rosen Vladimirov
Telerik team
 answered on 29 Apr 2021
6 answers
895 views

I tried to redirect all traffic thru Fiddler by using redsocks and iptables. Plaintext HTTP seems to work fine, however HTTPS doesn't seem to work properly.

Initially I didn't want to use redsocks at all - however it seemed that Fiddler cannot work in the way similar to sniproxy: using iptables -j DNAT alone doesn't work at all.

Then, although redsocks supports http CONNECT proxy mode, Fiddler no longer shows domain names in intercepted CONNECT entries - IP addresses are shown instead. Fiddler also throws out certificate errors, even if I check the "ignore certificate errors" checkbox, the intercepted application (which already trusts FiddlerRoot certificate) still refuses to connect. I think this should be related to SNI.

I think if Fiddler could work in the way similar to sniproxy, this problem would no longer exist, probably.

Rosen Vladimirov
Telerik team
 answered on 26 Apr 2021
1 answer
12.1K+ views

Hello,

Is it possible to capture localhost (client and server) websockets communication?In my case, in the client side I am using javascript code to connect to the websocket server, that it is started using java language.

In fiddler I do not see anything...

 

Regards,

Ed

Rosen Vladimirov
Telerik team
 answered on 23 Apr 2021
6 answers
1.0K+ views
Hello,

Is there any way to decompress post data in Fiddler, sent from application? Post request to server contain headers like this:
Content-type: application/x-compressed-json
Content-length: 3xx

Sent JSON data is unreadable. Any ideas are welcome! 
Arthur
Top achievements
Rank 1
 answered on 21 Apr 2021
1 answer
199 views

Hi everyone. I'm using Fiddler Everywhere on mac to intercept calls from the smartphone app to the vaccum robot, so i can use those commands to integrate the robot into my home automation system (Home Assistant).
so I set up Fiddler Everywhere, set up the proxy in the ios wifi and installed the certificates, and correctly intercepted the commands sent.
however, there are some "parameters" that i can't intercept, let me explain with one of the cases as an example: the robot obviously drains the battery when it's working. when it finishes cleaning, it goes back to the charging base. keeping the mobile phone active during the robot charging process, I see that for every percentage point of charge acquired, a post call is sent, of which I see url, headers and payload, but there's absolutely no trace of that percentage value (or any other info related to the battery). however, obviously on the smartphone I see that variation, so somehow the information has to go through.
so the question is: what can be the case that I can't catch THAT particular detail? what tests can i perform?
I hope I've explained it well enough, if necessary I can provide screenshots (app screen and details of the intercepted traffic).

Thanks

Rosen Vladimirov
Telerik team
 answered on 21 Apr 2021
1 answer
175 views

hi 

telerik ... please help me 

what is it . fiddler cant capture this traffic ( from this software ). HTTPS / TLS  why ...  ??

what is solution  ??

Rosen Vladimirov
Telerik team
 answered on 21 Apr 2021
5 answers
1.8K+ views

I'm trying to capture HTTP requests from .Net code running within a website on my local IIS.  The calls are being made by proxy classes generated from a WSDL via a Connected Services reference.  The recipient of the calls is claiming that the requests contain invalid payloads and I want to see the raw outgoing request from my end.

The service my code is calling requires TLS 1.2 and a client certificate.  The code runs fine at runtime as long as I don't have Fiddler in the picture (other than the payload supposedly being incorrect).

I have configured the .Net web app to run through Fiddler as follows:

<defaultProxy enabled="true">
  <proxy proxyaddress="http://127.0.0.1:8888" bypassonlocal="false"  />
</defaultProxy>

 

In Fiddler I can see the CONNECT commands are failing.  I have the Fiddler HTTPS Protocols configured as "<client>;ssl3;tls1.0;tls1.1;tls1.2".  I have exported the client certificate from the certificate store as a .cer and have added the following code to the end of the OnBeforeRequest() method (hostname and cert name changed for illustrative purposes):

if (oSession.HTTPMethodIs("CONNECT"))
{     
    if (oSession.HostnameIs("service.hostname"))
    {
        oSession["https-Client-Certificate"] = "C:\\certs\\Fiddler\\serviceClientCert.cer";
    }     
}

 

The CONNECT request is as follows:

CONNECT service.hostname:443 HTTP/1.1
Host: service.hostname
 
A SSLv3-compatible ClientHello handshake was found. Fiddler extracted the parameters below.
 
Version: 3.3 (TLS/1.2)
Random: 60 6F C6 38 2E BC 87 BE 57 7C 55 C9 A7 B6 31 42 00 EE 66 35 37 A0 CD 4E 08 42 7D 45 4F 89 A4 CB
"Time": 3/8/2000 8:18:56 AM
SessionID: empty
Extensions:
    server_name service.hostname
    supported_groups    x25519 [0x1d], secp256r1 [0x17], secp384r1 [0x18]
    ec_point_formats    uncompressed [0x0]
    signature_algs  rsa_pss_rsae_sha256, rsa_pss_rsae_sha384, rsa_pss_rsae_sha512, rsa_pkcs1_sha256, rsa_pkcs1_sha384, rsa_pkcs1_sha1, ecdsa_secp256r1_sha256, ecdsa_secp384r1_sha384, ecdsa_sha1, dsa_sha1, rsa_pkcs1_sha512, ecdsa_secp521r1_sha512
    SessionTicket   empty
    extended_master_secret  empty
    renegotiation_info  00
Ciphers:
    [C02C]  TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
    [C02B]  TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
    [C030]  TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
    [C02F]  TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
    [009F]  TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
    [009E]  TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
    [C024]  TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
    [C023]  TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
    [C028]  TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
    [C027]  TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
    [C00A]  TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
    [C009]  TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
    [C014]  TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
    [C013]  TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
    [009D]  TLS_RSA_WITH_AES_256_GCM_SHA384
    [009C]  TLS_RSA_WITH_AES_128_GCM_SHA256
    [003D]  TLS_RSA_WITH_AES_256_CBC_SHA256
    [003C]  TLS_RSA_WITH_AES_128_CBC_SHA256
    [0035]  TLS_RSA_WITH_AES_256_CBC_SHA
    [002F]  TLS_RSA_WITH_AES_128_CBC_SHA
    [000A]  SSL_RSA_WITH_3DES_EDE_SHA
 
Compression:
    [00]    NO_COMPRESSION

 

The CONNECT response is as follows:

HTTP/1.1 200 Connection Established
FiddlerGateway: Direct
StartTime: 20:12:56.601
Connection: close
 
fiddler.network.https> HTTPS handshake to service.hostname (for #5) failed. System.ComponentModel.Win32Exception The credentials supplied to the package were not recognized

 

I'm not sure why I'm getting the error or what I can do to rectify the problem.

 

Nick Iliev
Telerik team
 answered on 13 Apr 2021
1 answer
696 views

Hello im trying to change the root CA that fiddler uses, i generated my own using openssl-

openssl genrsa -out rootCA.key 2048

and then

openssl req -x509 -new -nodes -key rootCA.key -sha1 -days 2048 -out rootCA.crt

 

then i went to about:config- and changed the fiddler.certmaker.bc.cert to the data inside the newly generated

crt file, and same with the fiddler.certmaker.bc.key, however whenever i load fiddler for some reason it writes the original certificate back to

fiddler.certmaker.bc.cert- i even tried replacing it in the windows registry at Computer\HKEY_CURRENT_USER\Software\Microsoft\Fiddler2\Prefs\.default but again it just wrote the original certificate back into it.

 

Nick Iliev
Telerik team
 answered on 06 Apr 2021
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