On Mon, Jan 31, 2005 at 12:42:17PM -0800, seberino@xxxxxxxxxxxxxxx wrote: > Thanks for your 2 links. I really did read both of them carefully. > They explained SYN, ACK and FIN but not URG, PSH and RST. > Do you have another great link to explain these last 3 flags? :) yeah--they're all within "The TCP/IP Guide" which I linked to; specifically: PSH: http://www.tcpipguide.com/free/t_TCPImmediateDataTransferPushFunction.htm URG: http://www.tcpipguide.com/free/t_TCPPriorityDataTransferUrgentFunction.htm RST: http://www.tcpipguide.com/free/t_TCPConnectionManagementandProblemHandlingtheConnec.htm you can also read some/all of RFC 793--TRANSMISSION CONTROL PROTOCOL: http://www.faqs.org/rfcs/rfc793.html specifically--the section on page 35 titled "Reset Generation" explains all three states that would lead to the generation of a RST packet, and all three specify the calculation of an acknowledgment number, whether the packet that leads to the state had the ACK bit set or not. this plus observation of real OS's in the real world sending real RST packets leads me to believe that a real RST packet should have the ACK bit set. note; however, that more often than not--i have been proven to be wrong on these types of things--so take what i say with a grain of salt. -j -- "When will I learn? The answer to life's problems aren't at the bottom of a bottle, they're on TV!" --The Simpsons
