Change the following:

1.  ICMP ECHO and TSTAMP replies are now rate limited.
  2.  RSTs generated due to packets sent to open and unopen ports
      are now limited by seperate counters.
  3.  Each rate limiting queue now has its own description, as
      follows:

      Limiting icmp unreach response from 439 to 200 packets per second
      Limiting closed port RST response from 283 to 200 packets per second
      Limiting open port RST response from 18724 to 200 packets per second
      Limiting icmp ping response from 211 to 200 packets per second
      Limiting icmp tstamp response from 394 to 200 packets per second

Submitted by: Mike Silbersack <silby@silby.com>

sys/netinet/icmp_var.h

@@ -77,6 +77,12 @@ struct	icmpstat {
 #ifdef _KERNEL
 SYSCTL_DECL(_net_inet_icmp);
 extern int badport_bandlim __P((int));
+#define BANDLIM_UNREACH 0
+#define BANDLIM_RST_NOTOPEN 1
+#define BANDLIM_RST_OPEN 2
+#define BANDLIM_ECHO 3
+#define BANDLIM_TSTAMP 4
+#define BANDLIM_MAX 4 
 #endif
 
 #endif

sys/netinet/ip_icmp.c

@@ -449,7 +449,10 @@ icmp_input(m, off, proto)
 			break;
 		}
 		icp->icmp_type = ICMP_ECHOREPLY;
-		goto reflect;
+		if (badport_bandlim(BANDLIM_ECHO) < 0)
+			goto freeit;
+		else
+			goto reflect;
 
 	case ICMP_TSTAMP:
 		if (!icmpbmcastecho
@@ -464,7 +467,10 @@ icmp_input(m, off, proto)
 		icp->icmp_type = ICMP_TSTAMPREPLY;
 		icp->icmp_rtime = iptime();
 		icp->icmp_ttime = icp->icmp_rtime;	/* bogus, do later! */
-		goto reflect;
+		if (badport_bandlim(BANDLIM_TSTAMP) < 0)
+			goto freeit;
+		else
+			goto reflect;
 
 	case ICMP_MASKREQ:
 #define	satosin(sa)	((struct sockaddr_in *)(sa))
@@ -821,16 +827,23 @@ ip_next_mtu(mtu, dir)
 int
 badport_bandlim(int which)
 {
-	static int lticks[2];
-	static int lpackets[2];
+	static int lticks[BANDLIM_MAX + 1];
+	static int lpackets[BANDLIM_MAX + 1];
 	int dticks;
+	const char *bandlimittype[] = {
+		"Limiting icmp unreach response",
+		"Limiting closed port RST response",
+		"Limiting open port RST response",
+		"Limiting icmp ping response",
+		"Limiting icmp tstamp response"
+		};
 
 	/*
 	 * Return ok status if feature disabled or argument out of
 	 * ranage.
 	 */
 
-	if (icmplim <= 0 || which >= 2 || which < 0)
+	if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
 		return(0);
 	dticks = ticks - lticks[which];
 
@@ -840,7 +853,8 @@ badport_bandlim(int which)
 
 	if ((unsigned int)dticks > hz) {
 		if (lpackets[which] > icmplim && icmplim_output) {
-			printf("icmp-response bandwidth limit %d/%d pps\n",
+			printf("%s from %d to %d packets per second\n",
+				bandlimittype[which],
 				lpackets[which],
 				icmplim
 			);

sys/netinet/tcp_input.c

@@ -392,6 +392,7 @@ tcp_input(m, off0, proto)
 	struct ip6_hdr *ip6 = NULL;
 	int isipv6;
 #endif /* INET6 */
+	int rstreason = 0; /* For badport_bandlim accounting purposes */
 
 #ifdef INET6
 	isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0;
@@ -641,11 +642,14 @@ tcp_input(m, off0, proto)
 				goto drop;
 			}
 		}
+		rstreason = BANDLIM_RST_NOTOPEN;
 		goto maybedropwithreset;
 	}
 	tp = intotcpcb(inp);
-	if (tp == 0)
+	if (tp == 0) {
+		rstreason = BANDLIM_RST_NOTOPEN;
 		goto maybedropwithreset;
+	}
 	if (tp->t_state == TCPS_CLOSED)
 		goto drop;
 
@@ -2259,7 +2263,9 @@ tcp_input(m, off0, proto)
 	 * we think we are under attack or not.
 	 */
 maybedropwithreset:
-	if (badport_bandlim(1) < 0)
+	if (rstreason != BANDLIM_RST_NOTOPEN)
+		rstreason = BANDLIM_RST_OPEN;
+	if (badport_bandlim(rstreason) < 0)
 		goto drop;
 	/* fall through */
 dropwithreset:

sys/netinet/tcp_reass.c

@@ -392,6 +392,7 @@ tcp_input(m, off0, proto)
 	struct ip6_hdr *ip6 = NULL;
 	int isipv6;
 #endif /* INET6 */
+	int rstreason = 0; /* For badport_bandlim accounting purposes */
 
 #ifdef INET6
 	isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0;
@@ -641,11 +642,14 @@ tcp_input(m, off0, proto)
 				goto drop;
 			}
 		}
+		rstreason = BANDLIM_RST_NOTOPEN;
 		goto maybedropwithreset;
 	}
 	tp = intotcpcb(inp);
-	if (tp == 0)
+	if (tp == 0) {
+		rstreason = BANDLIM_RST_NOTOPEN;
 		goto maybedropwithreset;
+	}
 	if (tp->t_state == TCPS_CLOSED)
 		goto drop;
 
@@ -2259,7 +2263,9 @@ tcp_input(m, off0, proto)
 	 * we think we are under attack or not.
 	 */
 maybedropwithreset:
-	if (badport_bandlim(1) < 0)
+	if (rstreason != BANDLIM_RST_NOTOPEN)
+		rstreason = BANDLIM_RST_OPEN;
+	if (badport_bandlim(rstreason) < 0)
 		goto drop;
 	/* fall through */
 dropwithreset:

sys/netinet/udp_usrreq.c

@@ -353,7 +353,7 @@ udp_input(m, off, proto)
 			udpstat.udps_noportbcast++;
 			goto bad;
 		}
-		if (badport_bandlim(0) < 0)
+		if (badport_bandlim(BANDLIM_UNREACH) < 0)
 			goto bad;
 		if (blackhole)
 			goto bad;