in syn_cache_get() we have received ACK and about to make a fully
	established TCP connection.  when we send RST, we need to follow
	RFC793 page 36 last paragraph, hence the diff.

	if you see "dropwithreset" label in tcp_input(), you see the change
	is right - when ACK bit is set it respond like this.

itojun


Index: tcp_input.c
===================================================================
RCS file: /cvsroot/src/sys/netinet/tcp_input.c,v
retrieving revision 1.196
diff -u -r1.196 tcp_input.c
--- tcp_input.c	22 Apr 2004 15:05:33 -0000	1.196
+++ tcp_input.c	24 Apr 2004 16:54:49 -0000
@@ -3436,8 +3436,7 @@
 	return (so);
 
 resetandabort:
-	(void) tcp_respond(NULL, m, m, th,
-			   th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK);
+	(void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST);
 abort:
 	if (so != NULL)
 		(void) soabort(so);