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_inarp *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, int do_proxy);
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_inarp *dst, struct sockaddr_dl *sdl);
97 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
98 static struct sockaddr_inarp *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, proxy_only;
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], 0);
183 rtn = set(argc, argv) ? 1 : 0;
189 search(0, nuke_entry);
191 if (argc == 2 && strncmp(argv[1], "pub", 3) == 0)
197 rtn = delete(argv[0], ch);
211 * Process a file to set standard arp entries
218 char line[100], arg[5][50], *args[5], *p;
220 if ((fp = fopen(name, "r")) == NULL)
221 err(1, "cannot open %s", name);
222 args[0] = &arg[0][0];
223 args[1] = &arg[1][0];
224 args[2] = &arg[2][0];
225 args[3] = &arg[3][0];
226 args[4] = &arg[4][0];
228 while(fgets(line, sizeof(line), fp) != NULL) {
229 if ((p = strchr(line, '#')) != NULL)
231 for (p = line; isblank(*p); p++);
232 if (*p == '\n' || *p == '\0')
234 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
235 arg[2], arg[3], arg[4]);
237 warnx("bad line: %s", line);
249 * Given a hostname, fills up a (static) struct sockaddr_inarp with
250 * the address of the host and returns a pointer to the
253 static struct sockaddr_inarp *
257 static struct sockaddr_inarp reply;
259 bzero(&reply, sizeof(reply));
260 reply.sin_len = sizeof(reply);
261 reply.sin_family = AF_INET;
262 reply.sin_addr.s_addr = inet_addr(host);
263 if (reply.sin_addr.s_addr == INADDR_NONE) {
264 if (!(hp = gethostbyname(host))) {
265 warnx("%s: %s", host, hstrerror(h_errno));
268 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
269 sizeof reply.sin_addr);
275 * Returns true if the type is a valid one for ARP.
296 * Set an individual arp entry
299 set(int argc, char **argv)
301 struct sockaddr_inarp *addr;
302 struct sockaddr_inarp *dst; /* what are we looking for */
303 struct sockaddr_dl *sdl;
304 struct rt_msghdr *rtm;
305 struct ether_addr *ea;
306 char *host = argv[0], *eaddr = argv[1];
307 struct sockaddr_dl sdl_m;
312 bzero(&sdl_m, sizeof(sdl_m));
313 sdl_m.sdl_len = sizeof(sdl_m);
314 sdl_m.sdl_family = AF_LINK;
319 doing_proxy = flags = proxy_only = expire_time = 0;
321 if (strncmp(argv[0], "temp", 4) == 0) {
324 size_t len = sizeof(max_age);
326 clock_gettime(CLOCK_MONOTONIC, &tp);
327 if (sysctlbyname("net.link.ether.inet.max_age",
328 &max_age, &len, NULL, 0) != 0)
329 err(1, "sysctlbyname");
330 expire_time = tp.tv_sec + max_age;
331 } else if (strncmp(argv[0], "pub", 3) == 0) {
332 flags |= RTF_ANNOUNCE;
334 if (argc && strncmp(argv[1], "only", 3) == 0) {
338 } else if (strncmp(argv[0], "blackhole", 9) == 0) {
339 if (flags & RTF_REJECT) {
340 printf("Choose one of blackhole or reject, not both.\n");
342 flags |= RTF_BLACKHOLE;
343 } else if (strncmp(argv[0], "reject", 6) == 0) {
344 if (flags & RTF_BLACKHOLE) {
345 printf("Choose one of blackhole or reject, not both.\n");
348 } else if (strncmp(argv[0], "trail", 5) == 0) {
349 /* XXX deprecated and undocumented feature */
350 printf("%s: Sending trailers is no longer supported\n",
355 ea = (struct ether_addr *)LLADDR(&sdl_m);
356 if (doing_proxy && !strcmp(eaddr, "auto")) {
357 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
358 printf("no interface found for %s\n",
359 inet_ntoa(dst->sin_addr));
362 sdl_m.sdl_alen = ETHER_ADDR_LEN;
364 struct ether_addr *ea1 = ether_aton(eaddr);
367 warnx("invalid Ethernet address '%s'", eaddr);
371 sdl_m.sdl_alen = ETHER_ADDR_LEN;
376 * In the case a proxy-arp entry is being added for
377 * a remote end point, the RTF_ANNOUNCE flag in the
378 * RTM_GET command is an indication to the kernel
379 * routing code that the interface associated with
380 * the prefix route covering the local end of the
381 * PPP link should be returned, on which ARP applies.
383 rtm = rtmsg(RTM_GET, dst, &sdl_m);
388 addr = (struct sockaddr_inarp *)(rtm + 1);
389 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
391 if ((sdl->sdl_family != AF_LINK) ||
392 (rtm->rtm_flags & RTF_GATEWAY) ||
393 !valid_type(sdl->sdl_type)) {
394 printf("cannot intuit interface index and type for %s\n", host);
397 sdl_m.sdl_type = sdl->sdl_type;
398 sdl_m.sdl_index = sdl->sdl_index;
399 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
403 * Display an individual arp entry
408 struct sockaddr_inarp *addr;
410 addr = getaddr(host);
413 if (0 == search(addr->sin_addr.s_addr, print_entry)) {
414 printf("%s (%s) -- no entry",
415 host, inet_ntoa(addr->sin_addr));
417 printf(" on %s", rifname);
425 * Delete an arp entry
428 delete(char *host, int do_proxy)
430 struct sockaddr_inarp *addr, *dst;
431 struct rt_msghdr *rtm;
432 struct sockaddr_dl *sdl;
433 struct sockaddr_dl sdl_m;
440 * Perform a regular entry delete first.
442 flags &= ~RTF_ANNOUNCE;
445 * setup the data structure to notify the kernel
446 * it is the ARP entry the RTM_GET is interested
449 bzero(&sdl_m, sizeof(sdl_m));
450 sdl_m.sdl_len = sizeof(sdl_m);
451 sdl_m.sdl_family = AF_LINK;
453 for (;;) { /* try twice */
454 rtm = rtmsg(RTM_GET, dst, &sdl_m);
459 addr = (struct sockaddr_inarp *)(rtm + 1);
460 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
463 * With the new L2/L3 restructure, the route
464 * returned is a prefix route. The important
465 * piece of information from the previous
466 * RTM_GET is the interface index. In the
467 * case of ECMP, the kernel will traverse
468 * the route group for the given entry.
470 if (sdl->sdl_family == AF_LINK &&
471 !(rtm->rtm_flags & RTF_GATEWAY) &&
472 valid_type(sdl->sdl_type) ) {
473 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
478 * Regualar entry delete failed, now check if there
479 * is a proxy-arp entry to remove.
481 if (flags & RTF_ANNOUNCE) {
482 fprintf(stderr, "delete: cannot locate %s\n",host);
486 flags |= RTF_ANNOUNCE;
488 rtm->rtm_flags |= RTF_LLDATA;
489 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
490 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
498 * Search the arp table and do some action on matching entries
501 search(u_long addr, action_fn *action)
505 char *lim, *buf, *next;
506 struct rt_msghdr *rtm;
507 struct sockaddr_inarp *sin2;
508 struct sockaddr_dl *sdl;
509 char ifname[IF_NAMESIZE];
510 int st, found_entry = 0;
516 mib[4] = NET_RT_FLAGS;
522 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
523 err(1, "route-sysctl-estimate");
524 if (needed == 0) /* empty table */
528 buf = reallocf(buf, needed);
530 errx(1, "could not reallocate memory");
531 st = sysctl(mib, 6, buf, &needed, NULL, 0);
532 if (st == 0 || errno != ENOMEM)
534 needed += needed / 8;
537 err(1, "actual retrieval of routing table");
539 for (next = buf; next < lim; next += rtm->rtm_msglen) {
540 rtm = (struct rt_msghdr *)next;
541 sin2 = (struct sockaddr_inarp *)(rtm + 1);
542 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
543 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
544 strcmp(ifname, rifname))
547 if (addr != sin2->sin_addr.s_addr)
551 (*action)(sdl, sin2, rtm);
554 return (found_entry);
558 * Display an arp entry
560 static char lifname[IF_NAMESIZE];
561 static int64_t lifindex = -1;
564 print_entry(struct sockaddr_dl *sdl,
565 struct sockaddr_inarp *addr, struct rt_msghdr *rtm)
569 struct iso88025_sockaddr_dl_data *trld;
573 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
574 sizeof addr->sin_addr, AF_INET);
581 if (h_errno == TRY_AGAIN)
584 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
586 if ((sdl->sdl_type == IFT_ETHER ||
587 sdl->sdl_type == IFT_L2VLAN ||
588 sdl->sdl_type == IFT_BRIDGE) &&
589 sdl->sdl_alen == ETHER_ADDR_LEN)
590 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
592 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
594 printf("%s", link_ntoa(sdl) + n);
597 printf("(incomplete)");
598 if (sdl->sdl_index != lifindex &&
599 if_indextoname(sdl->sdl_index, lifname) != NULL) {
600 lifindex = sdl->sdl_index;
601 printf(" on %s", lifname);
602 } else if (sdl->sdl_index == lifindex)
603 printf(" on %s", lifname);
604 if (rtm->rtm_rmx.rmx_expire == 0)
605 printf(" permanent");
607 static struct timespec tp;
609 clock_gettime(CLOCK_MONOTONIC, &tp);
610 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
611 printf(" expires in %d seconds", (int)expire_time);
615 if (addr->sin_other & SIN_PROXY)
616 printf(" published (proxy only)");
617 if (rtm->rtm_flags & RTF_ANNOUNCE)
618 printf(" published");
619 switch(sdl->sdl_type) {
621 printf(" [ethernet]");
624 printf(" [token-ring]");
625 trld = SDL_ISO88025(sdl);
626 if (trld->trld_rcf != 0) {
627 printf(" rt=%x", ntohs(trld->trld_rcf));
629 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
631 printf(":%x", ntohs(*(trld->trld_route[seg])));
644 printf(" [firewire]");
661 nuke_entry(struct sockaddr_dl *sdl __unused,
662 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused)
666 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
673 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
674 "usage: arp [-n] [-i interface] hostname",
675 " arp [-n] [-i interface] -a",
676 " arp -d hostname [pub]",
677 " arp -d [-i interface] -a",
678 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
679 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
684 static struct rt_msghdr *
685 rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl)
690 struct sockaddr_in so_mask, *som = &so_mask;
695 struct rt_msghdr m_rtm;
699 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
700 char *cp = m_rtmsg.m_space;
702 if (s < 0) { /* first time: open socket, get pid */
703 s = socket(PF_ROUTE, SOCK_RAW, 0);
708 bzero(&so_mask, sizeof(so_mask));
710 so_mask.sin_addr.s_addr = 0xffffffff;
714 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
717 if (cmd == RTM_DELETE)
719 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
720 rtm->rtm_flags = flags;
721 rtm->rtm_version = RTM_VERSION;
725 errx(1, "internal wrong cmd");
727 rtm->rtm_addrs |= RTA_GATEWAY;
728 rtm->rtm_rmx.rmx_expire = expire_time;
729 rtm->rtm_inits = RTV_EXPIRE;
730 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
734 dst->sin_other = SIN_PROXY;
736 rtm->rtm_addrs |= RTA_NETMASK;
737 rtm->rtm_flags &= ~RTF_HOST;
742 rtm->rtm_addrs |= RTA_DST;
744 #define NEXTADDR(w, s) \
746 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
747 bcopy((s), cp, sizeof(*(s))); \
752 NEXTADDR(RTA_DST, dst);
753 NEXTADDR(RTA_GATEWAY, sdl);
754 NEXTADDR(RTA_NETMASK, som);
756 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
759 rtm->rtm_seq = ++seq;
761 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
762 if (errno != ESRCH || cmd != RTM_DELETE) {
763 warn("writing to routing socket");
768 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
769 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
771 warn("read from routing socket");
776 * get_ether_addr - get the hardware address of an interface on the
777 * the same subnet as ipaddr.
782 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
784 struct ifreq *ifr, *ifend, *ifp;
786 struct sockaddr_dl *dla;
789 struct ifreq ifs[MAX_IFS];
793 sock = socket(AF_INET, SOCK_DGRAM, 0);
797 ifc.ifc_len = sizeof(ifs);
799 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
800 warnx("ioctl(SIOCGIFCONF)");
805 ((struct ifreq *)((char *)&(i)->ifr_addr \
806 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
809 * Scan through looking for an interface with an Internet
810 * address on the same subnet as `ipaddr'.
812 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
813 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
814 if (ifr->ifr_addr.sa_family != AF_INET)
816 strncpy(ifreq.ifr_name, ifr->ifr_name,
817 sizeof(ifreq.ifr_name));
818 ifreq.ifr_addr = ifr->ifr_addr;
820 * Check that the interface is up,
821 * and not point-to-point or loopback.
823 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
825 if ((ifreq.ifr_flags &
826 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
827 IFF_LOOPBACK|IFF_NOARP))
828 != (IFF_UP|IFF_BROADCAST))
831 * Get its netmask and check that it's on
834 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
836 mask = ((struct sockaddr_in *)
837 &ifreq.ifr_addr)->sin_addr.s_addr;
838 ina = ((struct sockaddr_in *)
839 &ifr->ifr_addr)->sin_addr.s_addr;
840 if ((ipaddr & mask) == (ina & mask))
841 break; /* ok, we got it! */
848 * Now scan through again looking for a link-level address
849 * for this interface.
852 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
853 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
854 ifr->ifr_addr.sa_family == AF_LINK)
859 * Found the link-level address - copy it out
861 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
862 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
863 printf("using interface %s for proxy with address ",
865 printf("%s\n", ether_ntoa(hwaddr));
866 retval = dla->sdl_alen;