[WT-support] UDP Error #10013: Problem solved!

dl2alf dl2alf at arcor.de
Tue Dec 29 18:30:19 CET 2009

this is for everyone who has trouble with the well known "Error opening UDP
socket #10013" when running wt.exe and wtDxTelnet.exe on the same computer.
I had this on a freshly installed WindowsXP SP3 and it took me quite a while
to find out a solution.

Please check the value of the following registry key:    
(REG_DWORD, Value 0,1, Default=0)

If it is set to 1, Windows will prevent address sharing (SO_REUSEADDR)
between processes so that if a process opens a socket, no other process can
reuse the same socket, e.g. can steal data from it. 
Exactly this happens, when running more than one WT - application on the
same machine, because they all share the same UDP - Port (default=9871).
Maybe this hidden setting is security driven and caused by a Windows Group
Policy or by the work of some security software. 
I don't know why but it seems that driver software for UMTS modems can also
cause this problem.
Simply set the value to 0 and everything is running fine.
Reference: http://technet.microsoft.com/en-us/library/cc781532(WS.10).aspx
Frank, DL2ALF

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