I have a C# DotNet application that sends and receives multicast packets, it functions perfectly on Vista however it fails on Windows 7 with an error:"An attempt was made to access a socket in a way forbidden by its access permissions".Could you please provide details on how to enable multicast on Windows 7.Thank youMichael

HiDisable firewall or add custom rulefrom advanced firewall settingsWindows start menu-> administrative tools-> windows firewall .......

Thank you for your reply.Unfortunately disabling the firewall makes no difference. Running as administrator makes no difference either.

What exactly do your application?

My application exchanges data between multiple computers using multicast RTP protocol.Similar to the codeplex project conferenceXP.

Maybe service handling data exchange is not running and this is why you get this error

I am sorry but I really have no idea what you are talking about.Are you suggesting W7 has a service that handles multicast data exchange?

OkDid you tried to run your application in compatibility mode?1. Go to Control Panel\Programs2. Click on Use an older program with this version of windows3. Click next button4. Click Not listed and click next button ( if it is listed select it and skip to step 6)5. Click Browse button and point to and open setup file6. Click Next button7. Click The program worken in earlied versions of windows but won't install or run now and click next button8. Mark windows vist or entry you want and click next button9. Click next and runFollow on screen instructions and if required make additional setting and changes

The program still fails.Even if it worked this would not be a suitable solution - I am a developer and I wish to distribute a software package that is compatible with W7.

Ok If you are developer of that program then you must debug it using IDE used for its development.Error shows that there is problem accessing socket.If you use VS then you must know that if you want your program to run on system other than that where it is developed you must install C++ runtime redistributable package before to run program

I have debug itthat is how I was able topost the exception and where it occured 'socket.bind'.I also stated that the the program ran perfectly in unicast mode. What would make you think that loading C++ runtime would make any differanceto aDotNet application?

MichaelWilson said:I have debug itthat is how I was able topost the exception and where it occured 'socket.bind'.I also stated that the the program ran perfectly in unicast mode. What would make you think that loading C++ runtime would make any differanceto aDotNet application?It is my mistake I messed things with C++, but if your code import functions this still can be valid.Where exactly you stated that it is working in unicast mode because I cannot see it?W7 comes with newer net framework, so better check latest documentation for changes in last version.I have no idea how you create and access sockets so I cannot help you in thisThis forum is for W7 problems. but not forum for programming issues. If you need help on this issue ask in C# language forum.

I have resolved the problem.The windows 7 "media sharing service" uses the same ports 5005 , 5004 which are the registered ports for RTP protocoland which are the sameports my multicast app uses.Beware anyone wanting to run RTP protocol on windows 7.

Hey Michel, Well am developping an application similar to video conferencing (just like your application).I based my application on an application that import LSTCommon.dll, MSR.LST.Net.Rtp.dll and NetworkingBasics.dll .I have some problems in sending the images of the video ..it work only with the first 2 images and then stop ..i guess itrs because am using an WINDOWS 7 and may be this dll for RTP ptocole are not compatible with W7.So i see that you have sold the problem can you tell me which tool you used to developp your application ?