Linux – How to kill a TCP connection using tcpkill utility

linuxnetstattcp

I'm trying to kill an ESTABLISHED TCP connection using tcpkill. The connection is an open HTTPS connection. It appears on netstat as:

tcp        0      0 X.X.X.X:55601         X.X.X.X:https    ESTABLISHED

So, as per the man page, I enter:

$ tcpkill -i eth1 -9 port 443

The tcpkill utility outputs:

tcpkill: listening on eth1 [port 443]

…and then just hangs. After waiting for about 15 minutes, I'm not sure what's going on here.

Am I doing something wrong?

Best Answer

For tcpkill to work (i.e., craft a reset packet that has the correct sequence number and source port), there must be traffic. If nothing more is printed then there is no traffic. To verify you could run tcpdump -i eth1 port 443.

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Since you only do this manually, you may have to add another check.

netstat -p

and kill the pid associated with your open socket, even if it is bash or sh.

Also, you mentioned that most of the time SIGTERM works. If that's the case, your app should catch the SIGTERM and jump into some graceful exit code that RSTs all open connections and then closes the socket.

HTH

Lots of TIME_WAIT connections in netstat (Windows Server 2008)

All the remote ports in range of 32768 - 61000 are in TIME_WAIT state and don't release even few tens of minutes after application termination. Our server was running for almost two years without restart.

I have found following: http://support.microsoft.com/kb/2553549

Best Answer

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