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Getting Network Layer packet details

Posted by kinshuk_mishra (kinshuk_mishra), 8 November 2003
Hi there,

  In my scripts I need to validate source and destination IP address from the packets I am getting on my machine. How can i check that.....?

For example:

I initiate a ftp session to linux box which in turn sends me ack for the request sent. Now I want to know the source and destination IP address from that ACK packet. How can i check that?

Thanks in advance.

Posted by admin (Graham Ellis), 9 November 2003
The standard socket API that's provided in Tcl works at a higher level that your computer's network interface. From reading your question, I think that you want to analyse all network packets received by your system,  whether or not they're addressed to that system, and to do this you need some drivers at a lower level.  I haven't come across any in Tcl, but I have come across snoop and snort;  Snort is open source (see and we ran it for sometime on our internal firewall;  you many find that there are elements of the source code that you can learn from, or you may find that using Snort to feed Expect offers you a possible solution.

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