--- tcp_input.c.orig	Tue Apr 20 15:09:15 1999
+++ tcp_input.c	Fri Jan 21 21:53:00 2000
@@ -398,12 +398,36 @@
 			    "Connection attempt to TCP %s:%d from %s:%d\n",
 			    buf, ntohs(ti->ti_dport), inet_ntoa(ti->ti_src),
 			    ntohs(ti->ti_sport));
-		}
+		} else if (tiflags & TH_ACK) {
+			/*
+			 * Alpha code in response to stream.c
+			 * - Omachonu Ogali <oogali@intranova.net>
+			 */
+			char buf[4*sizeof "123"];
+
+#ifdef ICMP_BANDLIM
+			if (badport_bandlim(1) < 0)
+				goto drop;
+#endif
+
+			strcpy(buf, inet_ntoa(ti->ti_dst));
+			log(LOG_INFO,
+			    "received TCP/ACK to non existant connection: %s:%d -> %s:%d\n",
+			    inet_ntoa(ti->ti_src), ntohs(ti->ti_sport), buf, ntohs(ti->ti_dport));
+
+			/*
+			 * Drop without reset to prevent smurf-like tcp
+			 * attack
+			 */
+
+			goto drop;
+		} else {
 #ifdef ICMP_BANDLIM
 		if (badport_bandlim(1) < 0)
 			goto drop;
 #endif
 		goto dropwithreset;
+		}
 	}
 	tp = intotcpcb(inp);
 	if (tp == 0)