2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
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13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
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23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
34 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $
35 * $DragonFly: src/sys/netinet/ip_icmp.c,v 1.10 2004/07/23 14:14:30 joerg Exp $
38 #include "opt_ipsec.h"
40 #include <sys/param.h>
41 #include <sys/systm.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
46 #include <sys/kernel.h>
47 #include <sys/sysctl.h>
48 #include <sys/in_cksum.h>
50 #include <machine/stdarg.h>
53 #include <net/if_types.h>
54 #include <net/route.h>
57 #include <netinet/in.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/in_var.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_icmp.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/icmp_var.h>
66 #include <netinet6/ipsec.h>
67 #include <netproto/key/key.h>
71 #include <netipsec/ipsec.h>
72 #include <netipsec/key.h>
77 * ICMP routines: error generation, receive packet processing, and
78 * routines to turnaround packets back to the originator, and
79 * host table maintenance routines.
82 static struct icmpstat icmpstat;
83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
84 &icmpstat, icmpstat, "");
86 static int icmpmaskrepl = 0;
87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
88 &icmpmaskrepl, 0, "");
90 static int drop_redirect = 0;
91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
92 &drop_redirect, 0, "");
94 static int log_redirect = 0;
95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
96 &log_redirect, 0, "");
101 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
102 * variable content is -1 and read-only.
105 static int icmplim = 200;
106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
110 static int icmplim = -1;
111 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
116 static int icmplim_output = 1;
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
118 &icmplim_output, 0, "");
121 * ICMP broadcast echo sysctl
124 static int icmpbmcastecho = 0;
125 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
126 &icmpbmcastecho, 0, "");
133 static void icmp_reflect (struct mbuf *);
134 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
135 static int ip_next_mtu (int, int);
137 extern struct protosw inetsw[];
140 * Generate an error packet of type error
141 * in response to bad packet ip.
144 icmp_error(n, type, code, dest, destifp)
148 struct ifnet *destifp;
150 struct ip *oip = mtod(n, struct ip *), *nip;
151 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
158 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
160 if (type != ICMP_REDIRECT)
161 icmpstat.icps_error++;
163 * Don't send error if not the first fragment of message.
164 * Don't error if the old packet protocol was ICMP
165 * error message, only known informational types.
167 if (oip->ip_off &~ (IP_MF|IP_DF))
169 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
170 n->m_len >= oiplen + ICMP_MINLEN &&
171 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
172 icmpstat.icps_oldicmp++;
175 /* Don't send error in response to a multicast or broadcast packet */
176 if (n->m_flags & (M_BCAST|M_MCAST))
179 * First, formulate icmp message
181 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
184 icmplen = min(oiplen + 8, oip->ip_len);
185 if (icmplen < sizeof(struct ip))
186 panic("icmp_error: bad length");
187 m->m_len = icmplen + ICMP_MINLEN;
188 MH_ALIGN(m, m->m_len);
189 icp = mtod(m, struct icmp *);
190 if ((u_int)type > ICMP_MAXTYPE)
192 icmpstat.icps_outhist[type]++;
193 icp->icmp_type = type;
194 if (type == ICMP_REDIRECT)
195 icp->icmp_gwaddr.s_addr = dest;
199 * The following assignments assume an overlay with the
200 * zeroed icmp_void field.
202 if (type == ICMP_PARAMPROB) {
203 icp->icmp_pptr = code;
205 } else if (type == ICMP_UNREACH &&
206 code == ICMP_UNREACH_NEEDFRAG && destifp) {
207 icp->icmp_nextmtu = htons(destifp->if_mtu);
211 icp->icmp_code = code;
212 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
216 * Convert fields to network representation.
218 nip->ip_len = htons(nip->ip_len);
219 nip->ip_off = htons(nip->ip_off);
222 * Now, copy old ip header (without options)
223 * in front of icmp message.
225 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
227 m->m_data -= sizeof(struct ip);
228 m->m_len += sizeof(struct ip);
229 m->m_pkthdr.len = m->m_len;
230 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
231 nip = mtod(m, struct ip *);
232 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
233 nip->ip_len = m->m_len;
234 nip->ip_vhl = IP_VHL_BORING;
235 nip->ip_p = IPPROTO_ICMP;
243 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
244 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
245 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
248 * Process a received ICMP message.
251 icmp_input(struct mbuf *m, ...)
255 struct ip *ip = mtod(m, struct ip *);
256 int icmplen = ip->ip_len;
258 struct in_ifaddr *ia;
259 void (*ctlfunc) (int, struct sockaddr *, void *);
260 int code, off, proto;
264 off = __va_arg(ap, int);
265 proto = __va_arg(ap, int);
271 * Locate icmp structure in mbuf, and check
272 * that not corrupted and of at least minimum length.
276 char buf[4 * sizeof "123"];
277 strcpy(buf, inet_ntoa(ip->ip_src));
278 printf("icmp_input from %s to %s, len %d\n",
279 buf, inet_ntoa(ip->ip_dst), icmplen);
282 if (icmplen < ICMP_MINLEN) {
283 icmpstat.icps_tooshort++;
286 i = hlen + min(icmplen, ICMP_ADVLENMIN);
287 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
288 icmpstat.icps_tooshort++;
291 ip = mtod(m, struct ip *);
294 icp = mtod(m, struct icmp *);
295 if (in_cksum(m, icmplen)) {
296 icmpstat.icps_checksum++;
302 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
304 * Deliver very specific ICMP type only.
306 switch (icp->icmp_type) {
317 printf("icmp_input, type %d code %d\n", icp->icmp_type,
322 * Message type specific processing.
324 if (icp->icmp_type > ICMP_MAXTYPE)
326 icmpstat.icps_inhist[icp->icmp_type]++;
327 code = icp->icmp_code;
328 switch (icp->icmp_type) {
332 case ICMP_UNREACH_NET:
333 case ICMP_UNREACH_HOST:
334 case ICMP_UNREACH_SRCFAIL:
335 case ICMP_UNREACH_NET_UNKNOWN:
336 case ICMP_UNREACH_HOST_UNKNOWN:
337 case ICMP_UNREACH_ISOLATED:
338 case ICMP_UNREACH_TOSNET:
339 case ICMP_UNREACH_TOSHOST:
340 case ICMP_UNREACH_HOST_PRECEDENCE:
341 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
342 code = PRC_UNREACH_NET;
345 case ICMP_UNREACH_NEEDFRAG:
350 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
351 * Treat subcodes 2,3 as immediate RST
353 case ICMP_UNREACH_PROTOCOL:
354 case ICMP_UNREACH_PORT:
355 code = PRC_UNREACH_PORT;
358 case ICMP_UNREACH_NET_PROHIB:
359 case ICMP_UNREACH_HOST_PROHIB:
360 case ICMP_UNREACH_FILTER_PROHIB:
361 code = PRC_UNREACH_ADMIN_PROHIB;
372 code += PRC_TIMXCEED_INTRANS;
378 code = PRC_PARAMPROB;
381 case ICMP_SOURCEQUENCH:
387 * Problem with datagram; advise higher level routines.
389 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
390 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
391 icmpstat.icps_badlen++;
394 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
395 /* Discard ICMP's in response to multicast packets */
396 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
400 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
402 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
406 * If we got a needfrag and there is a host route to the
407 * original destination, and the MTU is not locked, then
408 * set the MTU in the route to the suggested new value
409 * (if given) and then notify as usual. The ULPs will
410 * notice that the MTU has changed and adapt accordingly.
411 * If no new MTU was suggested, then we guess a new one
412 * less than the current value. If the new MTU is
413 * unreasonably small (arbitrarily set at 296), then
414 * we reset the MTU to the interface value and enable the
415 * lock bit, indicating that we are no longer doing MTU
418 if (code == PRC_MSGSIZE) {
422 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
423 RTF_CLONING | RTF_PRCLONING);
424 if (rt && (rt->rt_flags & RTF_HOST)
425 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
426 mtu = ntohs(icp->icmp_nextmtu);
428 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
431 printf("MTU for %s reduced to %d\n",
432 inet_ntoa(icmpsrc.sin_addr), mtu);
435 /* rt->rt_rmx.rmx_mtu =
436 rt->rt_ifp->if_mtu; */
437 rt->rt_rmx.rmx_locks |= RTV_MTU;
438 } else if (rt->rt_rmx.rmx_mtu > mtu) {
439 rt->rt_rmx.rmx_mtu = mtu;
448 * XXX if the packet contains [IPv4 AH TCP], we can't make a
449 * notification to TCP layer.
451 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
453 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
454 (void *)&icp->icmp_ip);
458 icmpstat.icps_badcode++;
463 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
464 icmpstat.icps_bmcastecho++;
467 icp->icmp_type = ICMP_ECHOREPLY;
469 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
477 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
478 icmpstat.icps_bmcasttstamp++;
481 if (icmplen < ICMP_TSLEN) {
482 icmpstat.icps_badlen++;
485 icp->icmp_type = ICMP_TSTAMPREPLY;
486 icp->icmp_rtime = iptime();
487 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
489 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
496 if (icmpmaskrepl == 0)
499 * We are not able to respond with all ones broadcast
500 * unless we receive it over a point-to-point interface.
502 if (icmplen < ICMP_MASKLEN)
504 switch (ip->ip_dst.s_addr) {
506 case INADDR_BROADCAST:
508 icmpdst.sin_addr = ip->ip_src;
512 icmpdst.sin_addr = ip->ip_dst;
514 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
515 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
520 icp->icmp_type = ICMP_MASKREPLY;
521 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
522 if (ip->ip_src.s_addr == 0) {
523 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
524 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
525 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
526 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
529 ip->ip_len += hlen; /* since ip_input deducts this */
530 icmpstat.icps_reflect++;
531 icmpstat.icps_outhist[icp->icmp_type]++;
539 src = ntohl(ip->ip_src.s_addr);
540 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
541 gw = ntohl(icp->icmp_gwaddr.s_addr);
542 printf("icmp redirect from %d.%d.%d.%d: "
543 "%d.%d.%d.%d => %d.%d.%d.%d\n",
544 (int)(src >> 24), (int)((src >> 16) & 0xff),
545 (int)((src >> 8) & 0xff), (int)(src & 0xff),
546 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
547 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
548 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
549 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
555 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
556 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
557 icmpstat.icps_badlen++;
561 * Short circuit routing redirects to force
562 * immediate change in the kernel's routing
563 * tables. The message is also handed to anyone
564 * listening on a raw socket (e.g. the routing
565 * daemon for use in updating its tables).
567 icmpgw.sin_addr = ip->ip_src;
568 icmpdst.sin_addr = icp->icmp_gwaddr;
571 char buf[4 * sizeof "123"];
572 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
574 printf("redirect dst %s to %s\n",
575 buf, inet_ntoa(icp->icmp_gwaddr));
578 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
579 rtredirect((struct sockaddr *)&icmpsrc,
580 (struct sockaddr *)&icmpdst,
581 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
582 (struct sockaddr *)&icmpgw, (struct rtentry **)0);
583 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
585 key_sa_routechange((struct sockaddr *)&icmpsrc);
590 * No kernel processing for the following;
591 * just fall through to send to raw listener.
594 case ICMP_ROUTERADVERT:
595 case ICMP_ROUTERSOLICIT:
596 case ICMP_TSTAMPREPLY:
604 rip_input(m, off, proto);
612 * Reflect the ip packet back to the source
618 struct ip *ip = mtod(m, struct ip *);
620 struct in_ifaddr *ia;
622 struct mbuf *opts = 0;
623 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
624 struct route *ro = NULL, rt;
626 if (!in_canforward(ip->ip_src) &&
627 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
628 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
629 m_freem(m); /* Bad return address */
630 icmpstat.icps_badaddr++;
631 goto done; /* Ip_output() will check for broadcast */
634 ip->ip_dst = ip->ip_src;
636 bzero(ro, sizeof(*ro));
638 * If the incoming packet was addressed directly to us,
639 * use dst as the src for the reply. Otherwise (broadcast
640 * or anonymous), use the address which corresponds
641 * to the incoming interface.
643 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
644 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
646 if (m->m_pkthdr.rcvif != NULL &&
647 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
648 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
649 if (ifa->ifa_addr->sa_family != AF_INET)
652 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
657 ia = ip_rtaddr(ip->ip_dst, ro);
658 /* We need a route to do anything useful. */
661 icmpstat.icps_noroute++;
665 t = IA_SIN(ia)->sin_addr;
667 ip->ip_ttl = ip_defttl;
675 * Retrieve any source routing from the incoming packet;
676 * add on any record-route or timestamp options.
678 cp = (u_char *) (ip + 1);
679 if ((opts = ip_srcroute()) == 0 &&
680 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) {
681 opts->m_len = sizeof(struct in_addr);
682 mtod(opts, struct in_addr *)->s_addr = 0;
687 printf("icmp_reflect optlen %d rt %d => ",
688 optlen, opts->m_len);
690 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
691 opt = cp[IPOPT_OPTVAL];
692 if (opt == IPOPT_EOL)
694 if (opt == IPOPT_NOP)
697 if (cnt < IPOPT_OLEN + sizeof(*cp))
699 len = cp[IPOPT_OLEN];
700 if (len < IPOPT_OLEN + sizeof(*cp) ||
705 * Should check for overflow, but it "can't happen"
707 if (opt == IPOPT_RR || opt == IPOPT_TS ||
708 opt == IPOPT_SECURITY) {
710 mtod(opts, caddr_t) + opts->m_len, len);
714 /* Terminate & pad, if necessary */
715 cnt = opts->m_len % 4;
717 for (; cnt < 4; cnt++) {
718 *(mtod(opts, caddr_t) + opts->m_len) =
725 printf("%d\n", opts->m_len);
729 * Now strip out original options by copying rest of first
730 * mbuf's data back, and adjust the IP length.
732 ip->ip_len -= optlen;
733 ip->ip_vhl = IP_VHL_BORING;
735 if (m->m_flags & M_PKTHDR)
736 m->m_pkthdr.len -= optlen;
737 optlen += sizeof(struct ip);
738 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
739 (unsigned)(m->m_len - sizeof(struct ip)));
741 m->m_flags &= ~(M_BCAST|M_MCAST);
742 icmp_send(m, opts, ro);
751 * Send an icmp packet back to the ip level,
752 * after supplying a checksum.
755 icmp_send(m, opts, rt)
760 struct ip *ip = mtod(m, struct ip *);
764 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
767 icp = mtod(m, struct icmp *);
769 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
772 m->m_pkthdr.rcvif = (struct ifnet *)0;
775 char buf[4 * sizeof "123"];
776 strcpy(buf, inet_ntoa(ip->ip_dst));
777 printf("icmp_send dst %s src %s\n",
778 buf, inet_ntoa(ip->ip_src));
781 (void) ip_output(m, opts, rt, 0, NULL, NULL);
791 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
797 * Return the next larger or smaller MTU plateau (table from RFC 1191)
798 * given current value MTU. If DIR is less than zero, a larger plateau
799 * is returned; otherwise, a smaller value is returned.
802 ip_next_mtu(mtu, dir)
806 static int mtutab[] = {
807 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
812 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
813 if (mtu >= mtutab[i])
821 return mtutab[i - 1];
824 if (mtutab[i] == 0) {
826 } else if(mtu > mtutab[i]) {
829 return mtutab[i + 1];
838 * badport_bandlim() - check for ICMP bandwidth limit
840 * Return 0 if it is ok to send an ICMP error response, -1 if we have
841 * hit our bandwidth limit and it is not ok.
843 * If icmplim is <= 0, the feature is disabled and 0 is returned.
845 * For now we separate the TCP and UDP subsystems w/ different 'which'
846 * values. We may eventually remove this separation (and simplify the
849 * Note that the printing of the error message is delayed so we can
850 * properly print the icmp error rate that the system was trying to do
851 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
852 * the 'final' error, but it doesn't make sense to solve the printing
853 * delay with more complex code.
857 badport_bandlim(int which)
859 static int lticks[BANDLIM_MAX + 1];
860 static int lpackets[BANDLIM_MAX + 1];
862 const char *bandlimittype[] = {
863 "Limiting icmp unreach response",
864 "Limiting icmp ping response",
865 "Limiting icmp tstamp response",
866 "Limiting closed port RST response",
867 "Limiting open port RST response"
871 * Return ok status if feature disabled or argument out of
875 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
877 dticks = ticks - lticks[which];
880 * reset stats when cumulative dt exceeds one second.
883 if ((unsigned int)dticks > hz) {
884 if (lpackets[which] > icmplim && icmplim_output) {
885 printf("%s from %d to %d packets per second\n",
886 bandlimittype[which],
891 lticks[which] = ticks;
899 if (++lpackets[which] > icmplim) {