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Posted 16 Nov 2003

Enhance netstat

, 16 Nov 2003
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This article shows an implementation of the main TCP/UDP functions of the IP Helper API that is used to get info about active connections including the process attached to a connection.

Sample Image - enetstat.jpg


The main idea of this project was already implemented and presented by some guys around here: using GetTcpTable and GetUdpTable to read connection states of running processes. Yet another thing that is mentioned in this kind of articles are two undocumented APIs from iphlpapi.dll: AllocateAndGetTcpExTableFromStack and AllocateAndGetUdpExTableFromStack. Using these APIs, we can get access to the name of the process that holds the running connection. Unfortunately it does work only with Win2000, WinXP or newer versions.


First of all, I'd like to mention there is something new regarding this subject. Enetstat will allow the user to close any "established" connection using the following API function:

DWORD SetTcpEntry(

Having an established connection, we can close it using the following state: MIB_TCP_STATE_DELETE_TCB.

<PRE lang=c++>MIB_TCPROW sKillConn; sKillConn.dwLocalAddr = (DWORD)ulLocIP; //local ip sKillConn.dwLocalPort = (DWORD)usLocalPort; //local port sKillConn.dwRemoteAddr = (DWORD)ulRemIP; //remote ip sKillConn.dwRemotePort = (DWORD)usRemPort; //remote port sKillConn.dwState = MIB_TCP_STATE_DELETE_TCB; DWORD dwRez = SetTcpEntry(&sKillConn);

That's all about it. My piece of code is not described in detail and I suppose there is no need for that as long as we already have a cool and detailed description made by Axel Charpentier.

Well, if you need any good reference about this subject you'll find it here:

Getting active TCP/UDP connections on a box, by Axel Charpentier.


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Comments and Discussions

GeneralRe: Windows 2000 and XP... Pin
y0da19-Nov-03 0:10
membery0da19-Nov-03 0:10 
GeneralRe: Windows 2000 and XP... Pin
Anonymous3-Dec-03 23:54
sussAnonymous3-Dec-03 23:54 
GeneralVery good Pin
Daniel Turini17-Nov-03 11:34
memberDaniel Turini17-Nov-03 11:34 
GeneralRe: Very good Pin
y0da18-Nov-03 2:46
membery0da18-Nov-03 2:46 

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