FullTcp and SYN/ACK

[Qingyue Shirley Wang <qingyue@cs.washington.edu>]

Hi all,

I'm using some simple tcl script to simulate web server and client
interactions.  One important thing is I need to have SYN, SYN/ACK, FIN, etc
enabled so I can see connection setup and teardown phases.  However, when I
created agents with type "TCP/FullTcp" and check the type of passing-by
packets:

hdr_tcp *tcpHdr = hdr_tcp::access(p); //p is a pointer to packet
int flags = tcpHdr->tcp_flags_ ;
if (flags & TH_SYN) {
	cout << "It is a SYN!" << endl;
}
if (flags & TH_SYN & TH_ACK) {
cout << "It is a SYN/ACK!" << endl;
}

I was unable to see any SYN or SYN/ACK.  Is there some flag I need to enable
before SYN are exchanges?

thanks,
Shirley