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Show First 20 Lines • Show All 1,186 Lines • ▼ Show 20 Lines	if ((thflags & TH_SYN) == 0) {
goto dropunlock;		goto dropunlock;
}		}
/*		/*
* (SYN\|ACK) is bogus on a listen socket.		* (SYN\|ACK) is bogus on a listen socket.
*/		*/
if (thflags & TH_ACK) {		if (thflags & TH_ACK) {
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))		if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
log(LOG_DEBUG, "%s; %s: Listen socket: "		log(LOG_DEBUG, "%s; %s: Listen socket: "
"SYN\|ACK invalid, segment rejected\n",		"SYN\|ACK invalid, segment ignored\n",
s, __func__);		s, __func__);
syncache_badack(&inc, port); /* XXX: Not needed! */
TCPSTAT_INC(tcps_badsyn);		TCPSTAT_INC(tcps_badsyn);
goto dropwithreset;		goto dropunlock;
}		}
/*		/*
* If the drop_synfin option is enabled, drop all		* If the drop_synfin option is enabled, drop all
* segments with both the SYN and FIN bits set.		* segments with both the SYN and FIN bits set.
* This prevents e.g. nmap from identifying the		* This prevents e.g. nmap from identifying the
* TCP/IP stack.		* TCP/IP stack.
* XXX: Poor reasoning. nmap has other methods		* XXX: Poor reasoning. nmap has other methods
* and is constantly refining its stack detection		* and is constantly refining its stack detection
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