can't receive UDP packages when wire-shark is off

Question

this is my first post in here. I have an embedded Ethernet PIC32 uC that is sending UDP packages on one specific port to my C# Program on my PC. With C# i want to grab this packages as follows:

 UdpClient udpClient = new UdpClient( 20011 );
 IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
        while (true)
        {
           byte[] content = udpClient.Receive(ref sender);
        }

A package looks like this (wireshark): Source: 192.168.1.38 Destination: 192.168.1.44 Protocol: UDP Length: 122 Source port: 1000 Destination port: 20011

The interesting part is, that everything works fine as long as the wire-shark software is running in background! As soon as I stop listening on wire-shark no more packages in c# where received.

Does anyone has an idea what is happening here?

Thanks for your answers Chris

no, it just waits on the receive line until I turn on wireshark again — user2204718, Mar 24 '13 at 16:35
honestly, that doesn't make any sense. I know of no way that WireShark could have that effect. — Peter Ritchie, Mar 24 '13 at 16:36
Thats why I put the question to this portal :) makes no sense for me as well. But I tried it a couple of times, it is an absolute repetitiv problem. — user2204718, Mar 24 '13 at 16:42

score 2 · Answer 1 · answered Apr 11 '13 at 12:25

2

The problem was that the destination MAC Address was not resolved by the client correctly. Thanks for your hints

answered Apr 11 '13 at 12:25

user2204718

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xtof pernod · Answer 2 · 2013-03-24T17:32:10.407

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Is your machine really 192.168.1.44 ? If not, you are seeing the packets because wireshark puts the infterface in "promiscous" mode while it's running; if it resets the interface to normal mode, you don't see them anymore.

edited Mar 24 '13 at 17:32

answered Mar 24 '13 at 15:13

xtof pernod

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Is there any other point to receive the packets when my interface is in promiscous mode? – user2204718 Mar 24 '13 at 16:38

score 0 · Answer 3 · answered Mar 24 '13 at 15:15

0

Do you have an entry in the Windows Firewall? Does it work if you disable Windows Firewall temporarily?

answered Mar 24 '13 at 15:15

Richard

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same behavior when I turn off windows firewall completely – user2204718 Mar 24 '13 at 15:52

can't receive UDP packages when wire-shark is off

3 Answers3

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