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Hello world,
I am currently facing an ugly problem after our admin installed windows updates.
We have a service running on a server in our local network.
It registers itself on startup in a database, writing its ip and the number of a dynamically assigned port for UDP communication.
Clients in our network read the values on startup and send their IP and their dynamically assigned port via UDP to the server, so that the server can register them and was then able to send information via UDP to the clients for various purposes.

Everything worked fine until the admin updated my Win 7 installation during my vacation. It just doesn't work anymore.
Fact is that it worked before, and it still works for all other machines that are using XP.

I am not well educated on this kind of topic so I googled a lot yesterday in order to understand the problem so I can fix it. There were some posts regarding this issue, but it seems that most of them were able to work around this opening ports in their windows firewall.
It also seems that there was a change in one of the last updates, but it just doesn't make sense to me.

All firewalls are disabled in our local network.
I tried to use Wireshark to find out if any packages are sent, but it doesn't seem to send anything, even if the debugger show the tries in the console....
Our network uses both IPv4 and IPv6 enabled.
I can ping the servers IP but not telnet it using ip and port (I have no deep knowledge on telnet so far, so this information might be of any value).

So now I am stuck and the admin is away for the next weeks (its always the same, isn't it?) for a vacation.


UPDATE:
we just figured out that only Win7 64 bit machines are affected... Win7 32 bit seems to work.
That was wrong, unfortunately our admin installed a virtual network adapter (Oracle Virtual Box) on all the Win 7 64bit machines together with the updates... So it wasn't obvious to spot the problem right away...
Disabling the virtual network adapter did the job and everything started to work again.


best regards and have a nice day
Andy
Posted
Updated 14-Nov-11 22:50pm
v3
Comments
Timberbird 15-Nov-11 2:53am    
Well, if you know which updates were installed, you can always uninstall them one by one :).
The only recent update concerning UDP I've heard about is that one: http://technet.microsoft.com/en-us/security/bulletin/ms11-083 ; however, it is said to be critical and not causing any problems. Are you sure the problem is with UDP? The client part that you use, does it start normally and then say it cannot connect to the server? Is there anything on that error in Event Log?
hoernchenmeister 15-Nov-11 3:01am    
The program starts normally not causing any problems nor throwing any errors...
I handle the error event of the UDP component but there is nothing...
Like it just doesnt send or receive anything....
If I run the server/client setup in my project locally everything works fine until I try to reach out to the remote server in our network...

My colleague also faces the same problem after the updates but we are not authorized to uninstall any updates nor to install updates...

I have very little technical knowledge on this topic but my first thought was that the update closed something that was open before... (yeah, that sounded technical *LG*) ;)
Timberbird 15-Nov-11 3:21am    
OK, didn't figure out that is your application and can be debugged. So this application at least connects to DB and gets server address/port pair. Then it attempts to send data and... nothing, no data sent on any network interface and no error?
About telnet: does it work on XP machines?
hoernchenmeister 15-Nov-11 3:23am    
The returned server address/port is returned correctly.
I am also not good using wireshark, but I checked the complete list it collects when the application tries to connect and couldn't find anything.
The telnet command I am using:
telnet ip port
doesn't work on the XP machines :(
Timberbird 15-Nov-11 3:33am    
My bad, telnet won't show anything anyway - it's UDP after all, there are other utilities for this protocol (like netcat). Unfortunately I've never used Wireshark myself, sticking with CommView... which filters do you set?

1 solution

Unfortunately our admin installed a virtual network adapter (Oracle Virtual Box) on all the Win 7 64bit machines together with the updates... So it wasn't obvious to spot the problem right away...

Disabling the virtual network adapter did the job and everything started to work again.
 
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