2 * Copyright (c) 1984, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Sun Microsystems, Inc.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 static char const copyright[] =
36 "@(#) Copyright (c) 1984, 1993\n\
37 The Regents of the University of California. All rights reserved.\n";
41 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
48 * arp - display, set, and delete arp table entries
52 #include <sys/param.h>
54 #include <sys/socket.h>
55 #include <sys/sockio.h>
56 #include <sys/sysctl.h>
57 #include <sys/ioctl.h>
61 #include <net/if_dl.h>
62 #include <net/if_types.h>
63 #include <net/route.h>
64 #include <net/iso88025.h>
66 #include <netinet/in.h>
67 #include <netinet/if_ether.h>
69 #include <arpa/inet.h>
83 typedef void (action_fn)(struct sockaddr_dl *sdl,
84 struct sockaddr_in *s_in, struct rt_msghdr *rtm);
86 static int search(u_long addr, action_fn *action);
87 static action_fn print_entry;
88 static action_fn nuke_entry;
90 static int delete(char *host);
91 static void usage(void);
92 static int set(int argc, char **argv);
93 static int get(char *host);
94 static int file(char *name);
95 static struct rt_msghdr *rtmsg(int cmd,
96 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
97 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
98 static struct sockaddr_in *getaddr(char *host);
99 static int valid_type(int type);
101 static int nflag; /* no reverse dns lookups */
102 static char *rifname;
104 static time_t expire_time;
105 static int flags, doing_proxy;
107 /* which function we're supposed to do */
114 #define SETFUNC(f) { if (func) usage(); func = (f); }
117 main(int argc, char *argv[])
121 int aflag = 0; /* do it for all entries */
123 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
156 if (func != F_GET && !(func == F_DELETE && aflag))
157 errx(1, "-i not applicable to this operation");
158 if (if_nametoindex(rifname) == 0) {
160 errx(1, "interface %s does not exist", rifname);
162 err(1, "if_nametoindex(%s)", rifname);
170 search(0, print_entry);
179 if (argc < 2 || argc > 6)
181 if (func == F_REPLACE)
182 (void)delete(argv[0]);
183 rtn = set(argc, argv) ? 1 : 0;
189 search(0, nuke_entry);
193 rtn = delete(argv[0]);
207 * Process a file to set standard arp entries
214 char line[100], arg[5][50], *args[5], *p;
216 if ((fp = fopen(name, "r")) == NULL)
217 err(1, "cannot open %s", name);
218 args[0] = &arg[0][0];
219 args[1] = &arg[1][0];
220 args[2] = &arg[2][0];
221 args[3] = &arg[3][0];
222 args[4] = &arg[4][0];
224 while(fgets(line, sizeof(line), fp) != NULL) {
225 if ((p = strchr(line, '#')) != NULL)
227 for (p = line; isblank(*p); p++);
228 if (*p == '\n' || *p == '\0')
230 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
231 arg[2], arg[3], arg[4]);
233 warnx("bad line: %s", line);
245 * Given a hostname, fills up a (static) struct sockaddr_in with
246 * the address of the host and returns a pointer to the
249 static struct sockaddr_in *
253 static struct sockaddr_in reply;
255 bzero(&reply, sizeof(reply));
256 reply.sin_len = sizeof(reply);
257 reply.sin_family = AF_INET;
258 reply.sin_addr.s_addr = inet_addr(host);
259 if (reply.sin_addr.s_addr == INADDR_NONE) {
260 if (!(hp = gethostbyname(host))) {
261 warnx("%s: %s", host, hstrerror(h_errno));
264 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
265 sizeof reply.sin_addr);
271 * Returns true if the type is a valid one for ARP.
292 * Set an individual arp entry
295 set(int argc, char **argv)
297 struct sockaddr_in *addr;
298 struct sockaddr_in *dst; /* what are we looking for */
299 struct sockaddr_dl *sdl;
300 struct rt_msghdr *rtm;
301 struct ether_addr *ea;
302 char *host = argv[0], *eaddr = argv[1];
303 struct sockaddr_dl sdl_m;
308 bzero(&sdl_m, sizeof(sdl_m));
309 sdl_m.sdl_len = sizeof(sdl_m);
310 sdl_m.sdl_family = AF_LINK;
315 doing_proxy = flags = expire_time = 0;
317 if (strncmp(argv[0], "temp", 4) == 0) {
320 size_t len = sizeof(max_age);
322 clock_gettime(CLOCK_MONOTONIC, &tp);
323 if (sysctlbyname("net.link.ether.inet.max_age",
324 &max_age, &len, NULL, 0) != 0)
325 err(1, "sysctlbyname");
326 expire_time = tp.tv_sec + max_age;
327 } else if (strncmp(argv[0], "pub", 3) == 0) {
328 flags |= RTF_ANNOUNCE;
330 if (argc && strncmp(argv[1], "only", 3) == 0) {
332 * Compatibility: in pre FreeBSD 8 times
333 * the "only" keyword used to mean that
334 * an ARP entry should be announced, but
335 * not installed into routing table.
339 } else if (strncmp(argv[0], "blackhole", 9) == 0) {
340 if (flags & RTF_REJECT) {
341 printf("Choose one of blackhole or reject, not both.\n");
343 flags |= RTF_BLACKHOLE;
344 } else if (strncmp(argv[0], "reject", 6) == 0) {
345 if (flags & RTF_BLACKHOLE) {
346 printf("Choose one of blackhole or reject, not both.\n");
349 } else if (strncmp(argv[0], "trail", 5) == 0) {
350 /* XXX deprecated and undocumented feature */
351 printf("%s: Sending trailers is no longer supported\n",
356 ea = (struct ether_addr *)LLADDR(&sdl_m);
357 if (doing_proxy && !strcmp(eaddr, "auto")) {
358 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
359 printf("no interface found for %s\n",
360 inet_ntoa(dst->sin_addr));
363 sdl_m.sdl_alen = ETHER_ADDR_LEN;
365 struct ether_addr *ea1 = ether_aton(eaddr);
368 warnx("invalid Ethernet address '%s'", eaddr);
372 sdl_m.sdl_alen = ETHER_ADDR_LEN;
377 * In the case a proxy-arp entry is being added for
378 * a remote end point, the RTF_ANNOUNCE flag in the
379 * RTM_GET command is an indication to the kernel
380 * routing code that the interface associated with
381 * the prefix route covering the local end of the
382 * PPP link should be returned, on which ARP applies.
384 rtm = rtmsg(RTM_GET, dst, &sdl_m);
389 addr = (struct sockaddr_in *)(rtm + 1);
390 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
392 if ((sdl->sdl_family != AF_LINK) ||
393 (rtm->rtm_flags & RTF_GATEWAY) ||
394 !valid_type(sdl->sdl_type)) {
395 printf("cannot intuit interface index and type for %s\n", host);
398 sdl_m.sdl_type = sdl->sdl_type;
399 sdl_m.sdl_index = sdl->sdl_index;
400 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
404 * Display an individual arp entry
409 struct sockaddr_in *addr;
411 addr = getaddr(host);
414 if (0 == search(addr->sin_addr.s_addr, print_entry)) {
415 printf("%s (%s) -- no entry",
416 host, inet_ntoa(addr->sin_addr));
418 printf(" on %s", rifname);
426 * Delete an arp entry
431 struct sockaddr_in *addr, *dst;
432 struct rt_msghdr *rtm;
433 struct sockaddr_dl *sdl;
434 struct sockaddr_dl sdl_m;
441 * Perform a regular entry delete first.
443 flags &= ~RTF_ANNOUNCE;
446 * setup the data structure to notify the kernel
447 * it is the ARP entry the RTM_GET is interested
450 bzero(&sdl_m, sizeof(sdl_m));
451 sdl_m.sdl_len = sizeof(sdl_m);
452 sdl_m.sdl_family = AF_LINK;
454 for (;;) { /* try twice */
455 rtm = rtmsg(RTM_GET, dst, &sdl_m);
460 addr = (struct sockaddr_in *)(rtm + 1);
461 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
464 * With the new L2/L3 restructure, the route
465 * returned is a prefix route. The important
466 * piece of information from the previous
467 * RTM_GET is the interface index. In the
468 * case of ECMP, the kernel will traverse
469 * the route group for the given entry.
471 if (sdl->sdl_family == AF_LINK &&
472 !(rtm->rtm_flags & RTF_GATEWAY) &&
473 valid_type(sdl->sdl_type) ) {
474 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
479 * Regualar entry delete failed, now check if there
480 * is a proxy-arp entry to remove.
482 if (flags & RTF_ANNOUNCE) {
483 fprintf(stderr, "delete: cannot locate %s\n",host);
487 flags |= RTF_ANNOUNCE;
489 rtm->rtm_flags |= RTF_LLDATA;
490 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
491 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
499 * Search the arp table and do some action on matching entries
502 search(u_long addr, action_fn *action)
506 char *lim, *buf, *next;
507 struct rt_msghdr *rtm;
508 struct sockaddr_in *sin2;
509 struct sockaddr_dl *sdl;
510 char ifname[IF_NAMESIZE];
511 int st, found_entry = 0;
517 mib[4] = NET_RT_FLAGS;
523 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
524 err(1, "route-sysctl-estimate");
525 if (needed == 0) /* empty table */
529 buf = reallocf(buf, needed);
531 errx(1, "could not reallocate memory");
532 st = sysctl(mib, 6, buf, &needed, NULL, 0);
533 if (st == 0 || errno != ENOMEM)
535 needed += needed / 8;
538 err(1, "actual retrieval of routing table");
540 for (next = buf; next < lim; next += rtm->rtm_msglen) {
541 rtm = (struct rt_msghdr *)next;
542 sin2 = (struct sockaddr_in *)(rtm + 1);
543 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
544 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
545 strcmp(ifname, rifname))
548 if (addr != sin2->sin_addr.s_addr)
552 (*action)(sdl, sin2, rtm);
555 return (found_entry);
559 * Display an arp entry
561 static char lifname[IF_NAMESIZE];
562 static int64_t lifindex = -1;
565 print_entry(struct sockaddr_dl *sdl,
566 struct sockaddr_in *addr, struct rt_msghdr *rtm)
570 struct iso88025_sockaddr_dl_data *trld;
574 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
575 sizeof addr->sin_addr, AF_INET);
582 if (h_errno == TRY_AGAIN)
585 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
587 if ((sdl->sdl_type == IFT_ETHER ||
588 sdl->sdl_type == IFT_L2VLAN ||
589 sdl->sdl_type == IFT_BRIDGE) &&
590 sdl->sdl_alen == ETHER_ADDR_LEN)
591 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
593 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
595 printf("%s", link_ntoa(sdl) + n);
598 printf("(incomplete)");
599 if (sdl->sdl_index != lifindex &&
600 if_indextoname(sdl->sdl_index, lifname) != NULL) {
601 lifindex = sdl->sdl_index;
602 printf(" on %s", lifname);
603 } else if (sdl->sdl_index == lifindex)
604 printf(" on %s", lifname);
605 if (rtm->rtm_rmx.rmx_expire == 0)
606 printf(" permanent");
608 static struct timespec tp;
610 clock_gettime(CLOCK_MONOTONIC, &tp);
611 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
612 printf(" expires in %d seconds", (int)expire_time);
616 if (rtm->rtm_flags & RTF_ANNOUNCE)
617 printf(" published");
618 switch(sdl->sdl_type) {
620 printf(" [ethernet]");
623 printf(" [token-ring]");
624 trld = SDL_ISO88025(sdl);
625 if (trld->trld_rcf != 0) {
626 printf(" rt=%x", ntohs(trld->trld_rcf));
628 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
630 printf(":%x", ntohs(*(trld->trld_route[seg])));
643 printf(" [firewire]");
660 nuke_entry(struct sockaddr_dl *sdl __unused,
661 struct sockaddr_in *addr, struct rt_msghdr *rtm __unused)
665 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
672 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
673 "usage: arp [-n] [-i interface] hostname",
674 " arp [-n] [-i interface] -a",
675 " arp -d hostname [pub]",
676 " arp -d [-i interface] -a",
677 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
678 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
683 static struct rt_msghdr *
684 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
689 struct sockaddr_in so_mask, *som = &so_mask;
694 struct rt_msghdr m_rtm;
698 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
699 char *cp = m_rtmsg.m_space;
701 if (s < 0) { /* first time: open socket, get pid */
702 s = socket(PF_ROUTE, SOCK_RAW, 0);
707 bzero(&so_mask, sizeof(so_mask));
709 so_mask.sin_addr.s_addr = 0xffffffff;
713 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
716 if (cmd == RTM_DELETE)
718 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
719 rtm->rtm_flags = flags;
720 rtm->rtm_version = RTM_VERSION;
724 errx(1, "internal wrong cmd");
726 rtm->rtm_addrs |= RTA_GATEWAY;
727 rtm->rtm_rmx.rmx_expire = expire_time;
728 rtm->rtm_inits = RTV_EXPIRE;
729 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
731 rtm->rtm_addrs |= RTA_NETMASK;
732 rtm->rtm_flags &= ~RTF_HOST;
736 rtm->rtm_addrs |= RTA_DST;
738 #define NEXTADDR(w, s) \
740 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
741 bcopy((s), cp, sizeof(*(s))); \
746 NEXTADDR(RTA_DST, dst);
747 NEXTADDR(RTA_GATEWAY, sdl);
748 NEXTADDR(RTA_NETMASK, som);
750 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
753 rtm->rtm_seq = ++seq;
755 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
756 if (errno != ESRCH || cmd != RTM_DELETE) {
757 warn("writing to routing socket");
762 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
763 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
765 warn("read from routing socket");
770 * get_ether_addr - get the hardware address of an interface on the
771 * the same subnet as ipaddr.
776 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
778 struct ifreq *ifr, *ifend, *ifp;
780 struct sockaddr_dl *dla;
783 struct ifreq ifs[MAX_IFS];
787 sock = socket(AF_INET, SOCK_DGRAM, 0);
791 ifc.ifc_len = sizeof(ifs);
793 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
794 warnx("ioctl(SIOCGIFCONF)");
799 ((struct ifreq *)((char *)&(i)->ifr_addr \
800 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
803 * Scan through looking for an interface with an Internet
804 * address on the same subnet as `ipaddr'.
806 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
807 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
808 if (ifr->ifr_addr.sa_family != AF_INET)
810 strncpy(ifreq.ifr_name, ifr->ifr_name,
811 sizeof(ifreq.ifr_name));
812 ifreq.ifr_addr = ifr->ifr_addr;
814 * Check that the interface is up,
815 * and not point-to-point or loopback.
817 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
819 if ((ifreq.ifr_flags &
820 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
821 IFF_LOOPBACK|IFF_NOARP))
822 != (IFF_UP|IFF_BROADCAST))
825 * Get its netmask and check that it's on
828 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
830 mask = ((struct sockaddr_in *)
831 &ifreq.ifr_addr)->sin_addr.s_addr;
832 ina = ((struct sockaddr_in *)
833 &ifr->ifr_addr)->sin_addr.s_addr;
834 if ((ipaddr & mask) == (ina & mask))
835 break; /* ok, we got it! */
842 * Now scan through again looking for a link-level address
843 * for this interface.
846 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
847 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
848 ifr->ifr_addr.sa_family == AF_LINK)
853 * Found the link-level address - copy it out
855 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
856 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
857 printf("using interface %s for proxy with address ",
859 printf("%s\n", ether_ntoa(hwaddr));
860 retval = dla->sdl_alen;