Date: Tue, 06 Aug 2002 23:27:04 +0430 From: "soheil h" <soheil_h_y@hotmail.com> To: freebsd-net@FreeBSD.ORG Subject: Re: TCP HEADER Message-ID: <F792KJPOGMRcasJsfyb0000e18a@hotmail.com>
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Hi list In any tcp/ip packet pass through my FreeBSD gateway i duplicate the tcp window by changing /usr/src/sys/netinet/ip_input.c . The clients just stay at SYN-SENT state ( the ACK of their SYN ) is not recieved . when i run tcpdump on the gateway it show something like this: time x.x.x.x.p > y.y.y.y.80 : S seq1:seq1(0) win x < options > /in time x.x.x.x.p > y.y.y.y.80 : S seq1:seq1(0) win 2*x <options > /out (no SYN|ACK recieved ) !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (just for test when the y.y.y.y is a site that i can access and no packet from x.x.x.x recieved showed by the tcpdump at y.y.y.y;) it shows when the tcp/ip packet pass through me the window size is duplicated . ( no change in any other members ). as stated in Stevens' TCP/IP Illustrated the window size is just for date transition not for the connection stablishment. i think some host between drop my packet but i correct the cksums : in my code ,after the change, the checksums are treated as ip->ip_sum = in_cksum(m, hlen); th stands for the TCP header : len = ip->ip_len; th->th_sum = in_cksum(m, len); but i don't know what is the problem with my algorithm ? Please verify me if the cksum calculation is not true , or any other errors might be occured this is so emergency for me; Please help me! S.H.Y _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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