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 struct if_nameindex *ifnameindex;
109 /* which function we're supposed to do */
116 #define SETFUNC(f) { if (func) usage(); func = (f); }
119 main(int argc, char *argv[])
123 int aflag = 0; /* do it for all entries */
125 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
158 if (func != F_GET && !(func == F_DELETE && aflag))
159 errx(1, "-i not applicable to this operation");
160 if (if_nametoindex(rifname) == 0) {
162 errx(1, "interface %s does not exist", rifname);
164 err(1, "if_nametoindex(%s)", rifname);
172 search(0, print_entry);
181 if (argc < 2 || argc > 6)
183 if (func == F_REPLACE)
184 (void)delete(argv[0]);
185 rtn = set(argc, argv) ? 1 : 0;
191 search(0, nuke_entry);
195 rtn = delete(argv[0]);
205 if (ifnameindex != NULL)
206 if_freenameindex(ifnameindex);
212 * Process a file to set standard arp entries
219 char line[100], arg[5][50], *args[5], *p;
221 if ((fp = fopen(name, "r")) == NULL)
222 err(1, "cannot open %s", name);
223 args[0] = &arg[0][0];
224 args[1] = &arg[1][0];
225 args[2] = &arg[2][0];
226 args[3] = &arg[3][0];
227 args[4] = &arg[4][0];
229 while(fgets(line, sizeof(line), fp) != NULL) {
230 if ((p = strchr(line, '#')) != NULL)
232 for (p = line; isblank(*p); p++);
233 if (*p == '\n' || *p == '\0')
235 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
236 arg[2], arg[3], arg[4]);
238 warnx("bad line: %s", line);
250 * Given a hostname, fills up a (static) struct sockaddr_in with
251 * the address of the host and returns a pointer to the
254 static struct sockaddr_in *
258 static struct sockaddr_in reply;
260 bzero(&reply, sizeof(reply));
261 reply.sin_len = sizeof(reply);
262 reply.sin_family = AF_INET;
263 reply.sin_addr.s_addr = inet_addr(host);
264 if (reply.sin_addr.s_addr == INADDR_NONE) {
265 if (!(hp = gethostbyname(host))) {
266 warnx("%s: %s", host, hstrerror(h_errno));
269 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
270 sizeof reply.sin_addr);
276 * Returns true if the type is a valid one for ARP.
298 * Set an individual arp entry
301 set(int argc, char **argv)
303 struct sockaddr_in *addr;
304 struct sockaddr_in *dst; /* what are we looking for */
305 struct sockaddr_dl *sdl;
306 struct rt_msghdr *rtm;
307 struct ether_addr *ea;
308 char *host = argv[0], *eaddr = argv[1];
309 struct sockaddr_dl sdl_m;
314 bzero(&sdl_m, sizeof(sdl_m));
315 sdl_m.sdl_len = sizeof(sdl_m);
316 sdl_m.sdl_family = AF_LINK;
321 doing_proxy = flags = expire_time = 0;
323 if (strncmp(argv[0], "temp", 4) == 0) {
326 size_t len = sizeof(max_age);
328 clock_gettime(CLOCK_MONOTONIC, &tp);
329 if (sysctlbyname("net.link.ether.inet.max_age",
330 &max_age, &len, NULL, 0) != 0)
331 err(1, "sysctlbyname");
332 expire_time = tp.tv_sec + max_age;
333 } else if (strncmp(argv[0], "pub", 3) == 0) {
334 flags |= RTF_ANNOUNCE;
336 if (argc && strncmp(argv[1], "only", 3) == 0) {
338 * Compatibility: in pre FreeBSD 8 times
339 * the "only" keyword used to mean that
340 * an ARP entry should be announced, but
341 * not installed into routing table.
345 } else if (strncmp(argv[0], "blackhole", 9) == 0) {
346 if (flags & RTF_REJECT) {
347 printf("Choose one of blackhole or reject, not both.\n");
349 flags |= RTF_BLACKHOLE;
350 } else if (strncmp(argv[0], "reject", 6) == 0) {
351 if (flags & RTF_BLACKHOLE) {
352 printf("Choose one of blackhole or reject, not both.\n");
355 } else if (strncmp(argv[0], "trail", 5) == 0) {
356 /* XXX deprecated and undocumented feature */
357 printf("%s: Sending trailers is no longer supported\n",
362 ea = (struct ether_addr *)LLADDR(&sdl_m);
363 if (doing_proxy && !strcmp(eaddr, "auto")) {
364 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
365 printf("no interface found for %s\n",
366 inet_ntoa(dst->sin_addr));
369 sdl_m.sdl_alen = ETHER_ADDR_LEN;
371 struct ether_addr *ea1 = ether_aton(eaddr);
374 warnx("invalid Ethernet address '%s'", eaddr);
378 sdl_m.sdl_alen = ETHER_ADDR_LEN;
383 * In the case a proxy-arp entry is being added for
384 * a remote end point, the RTF_ANNOUNCE flag in the
385 * RTM_GET command is an indication to the kernel
386 * routing code that the interface associated with
387 * the prefix route covering the local end of the
388 * PPP link should be returned, on which ARP applies.
390 rtm = rtmsg(RTM_GET, dst, &sdl_m);
395 addr = (struct sockaddr_in *)(rtm + 1);
396 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
398 if ((sdl->sdl_family != AF_LINK) ||
399 (rtm->rtm_flags & RTF_GATEWAY) ||
400 !valid_type(sdl->sdl_type)) {
401 printf("cannot intuit interface index and type for %s\n", host);
404 sdl_m.sdl_type = sdl->sdl_type;
405 sdl_m.sdl_index = sdl->sdl_index;
406 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
410 * Display an individual arp entry
415 struct sockaddr_in *addr;
417 addr = getaddr(host);
420 if (0 == search(addr->sin_addr.s_addr, print_entry)) {
421 printf("%s (%s) -- no entry",
422 host, inet_ntoa(addr->sin_addr));
424 printf(" on %s", rifname);
432 * Delete an arp entry
437 struct sockaddr_in *addr, *dst;
438 struct rt_msghdr *rtm;
439 struct sockaddr_dl *sdl;
440 struct sockaddr_dl sdl_m;
447 * Perform a regular entry delete first.
449 flags &= ~RTF_ANNOUNCE;
452 * setup the data structure to notify the kernel
453 * it is the ARP entry the RTM_GET is interested
456 bzero(&sdl_m, sizeof(sdl_m));
457 sdl_m.sdl_len = sizeof(sdl_m);
458 sdl_m.sdl_family = AF_LINK;
460 for (;;) { /* try twice */
461 rtm = rtmsg(RTM_GET, dst, &sdl_m);
466 addr = (struct sockaddr_in *)(rtm + 1);
467 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
470 * With the new L2/L3 restructure, the route
471 * returned is a prefix route. The important
472 * piece of information from the previous
473 * RTM_GET is the interface index. In the
474 * case of ECMP, the kernel will traverse
475 * the route group for the given entry.
477 if (sdl->sdl_family == AF_LINK &&
478 !(rtm->rtm_flags & RTF_GATEWAY) &&
479 valid_type(sdl->sdl_type) ) {
480 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
485 * Regualar entry delete failed, now check if there
486 * is a proxy-arp entry to remove.
488 if (flags & RTF_ANNOUNCE) {
489 fprintf(stderr, "delete: cannot locate %s\n",host);
493 flags |= RTF_ANNOUNCE;
495 rtm->rtm_flags |= RTF_LLDATA;
496 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
497 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
505 * Search the arp table and do some action on matching entries
508 search(u_long addr, action_fn *action)
512 char *lim, *buf, *next;
513 struct rt_msghdr *rtm;
514 struct sockaddr_in *sin2;
515 struct sockaddr_dl *sdl;
516 char ifname[IF_NAMESIZE];
517 int st, found_entry = 0;
523 mib[4] = NET_RT_FLAGS;
529 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
530 err(1, "route-sysctl-estimate");
531 if (needed == 0) /* empty table */
535 buf = reallocf(buf, needed);
537 errx(1, "could not reallocate memory");
538 st = sysctl(mib, 6, buf, &needed, NULL, 0);
539 if (st == 0 || errno != ENOMEM)
541 needed += needed / 8;
544 err(1, "actual retrieval of routing table");
546 for (next = buf; next < lim; next += rtm->rtm_msglen) {
547 rtm = (struct rt_msghdr *)next;
548 sin2 = (struct sockaddr_in *)(rtm + 1);
549 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
550 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
551 strcmp(ifname, rifname))
554 if (addr != sin2->sin_addr.s_addr)
558 (*action)(sdl, sin2, rtm);
561 return (found_entry);
565 * Display an arp entry
569 print_entry(struct sockaddr_dl *sdl,
570 struct sockaddr_in *addr, struct rt_msghdr *rtm)
574 struct iso88025_sockaddr_dl_data *trld;
575 struct if_nameindex *p;
578 if (ifnameindex == NULL)
579 if ((ifnameindex = if_nameindex()) == NULL)
580 err(1, "cannot retrieve interface names");
583 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
584 sizeof addr->sin_addr, AF_INET);
591 if (h_errno == TRY_AGAIN)
594 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
596 if ((sdl->sdl_type == IFT_ETHER ||
597 sdl->sdl_type == IFT_L2VLAN ||
598 sdl->sdl_type == IFT_BRIDGE) &&
599 sdl->sdl_alen == ETHER_ADDR_LEN)
600 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
602 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
604 printf("%s", link_ntoa(sdl) + n);
607 printf("(incomplete)");
609 for (p = ifnameindex; p && ifnameindex->if_index &&
610 ifnameindex->if_name; p++) {
611 if (p->if_index == sdl->sdl_index) {
612 printf(" on %s", p->if_name);
617 if (rtm->rtm_rmx.rmx_expire == 0)
618 printf(" permanent");
620 static struct timespec tp;
622 clock_gettime(CLOCK_MONOTONIC, &tp);
623 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
624 printf(" expires in %d seconds", (int)expire_time);
628 if (rtm->rtm_flags & RTF_ANNOUNCE)
629 printf(" published");
630 switch(sdl->sdl_type) {
632 printf(" [ethernet]");
635 printf(" [token-ring]");
636 trld = SDL_ISO88025(sdl);
637 if (trld->trld_rcf != 0) {
638 printf(" rt=%x", ntohs(trld->trld_rcf));
640 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
642 printf(":%x", ntohs(*(trld->trld_route[seg])));
655 printf(" [firewire]");
661 printf(" [infiniband]");
675 nuke_entry(struct sockaddr_dl *sdl __unused,
676 struct sockaddr_in *addr, struct rt_msghdr *rtm)
680 if (rtm->rtm_flags & RTF_PINNED)
683 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
690 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
691 "usage: arp [-n] [-i interface] hostname",
692 " arp [-n] [-i interface] -a",
693 " arp -d hostname [pub]",
694 " arp -d [-i interface] -a",
695 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
696 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
701 static struct rt_msghdr *
702 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
707 struct sockaddr_in so_mask, *som = &so_mask;
712 struct rt_msghdr m_rtm;
716 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
717 char *cp = m_rtmsg.m_space;
719 if (s < 0) { /* first time: open socket, get pid */
720 s = socket(PF_ROUTE, SOCK_RAW, 0);
725 bzero(&so_mask, sizeof(so_mask));
727 so_mask.sin_addr.s_addr = 0xffffffff;
731 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
734 if (cmd == RTM_DELETE)
736 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
737 rtm->rtm_flags = flags;
738 rtm->rtm_version = RTM_VERSION;
742 errx(1, "internal wrong cmd");
744 rtm->rtm_addrs |= RTA_GATEWAY;
745 rtm->rtm_rmx.rmx_expire = expire_time;
746 rtm->rtm_inits = RTV_EXPIRE;
747 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
749 rtm->rtm_addrs |= RTA_NETMASK;
750 rtm->rtm_flags &= ~RTF_HOST;
754 rtm->rtm_addrs |= RTA_DST;
756 #define NEXTADDR(w, s) \
758 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
759 bcopy((s), cp, sizeof(*(s))); \
764 NEXTADDR(RTA_DST, dst);
765 NEXTADDR(RTA_GATEWAY, sdl);
766 NEXTADDR(RTA_NETMASK, som);
768 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
771 rtm->rtm_seq = ++seq;
773 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
774 if (errno != ESRCH || cmd != RTM_DELETE) {
775 warn("writing to routing socket");
780 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
781 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
783 warn("read from routing socket");
788 * get_ether_addr - get the hardware address of an interface on the
789 * the same subnet as ipaddr.
794 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
796 struct ifreq *ifr, *ifend, *ifp;
798 struct sockaddr_dl *dla;
801 struct ifreq ifs[MAX_IFS];
805 sock = socket(AF_INET, SOCK_DGRAM, 0);
809 ifc.ifc_len = sizeof(ifs);
811 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
812 warnx("ioctl(SIOCGIFCONF)");
817 ((struct ifreq *)((char *)&(i)->ifr_addr \
818 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
821 * Scan through looking for an interface with an Internet
822 * address on the same subnet as `ipaddr'.
824 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
825 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
826 if (ifr->ifr_addr.sa_family != AF_INET)
828 strncpy(ifreq.ifr_name, ifr->ifr_name,
829 sizeof(ifreq.ifr_name));
830 ifreq.ifr_addr = ifr->ifr_addr;
832 * Check that the interface is up,
833 * and not point-to-point or loopback.
835 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
837 if ((ifreq.ifr_flags &
838 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
839 IFF_LOOPBACK|IFF_NOARP))
840 != (IFF_UP|IFF_BROADCAST))
843 * Get its netmask and check that it's on
846 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
848 mask = ((struct sockaddr_in *)
849 &ifreq.ifr_addr)->sin_addr.s_addr;
850 ina = ((struct sockaddr_in *)
851 &ifr->ifr_addr)->sin_addr.s_addr;
852 if ((ipaddr & mask) == (ina & mask))
853 break; /* ok, we got it! */
860 * Now scan through again looking for a link-level address
861 * for this interface.
864 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
865 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
866 ifr->ifr_addr.sa_family == AF_LINK)
871 * Found the link-level address - copy it out
873 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
874 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
875 printf("using interface %s for proxy with address ",
877 printf("%s\n", ether_ntoa(hwaddr));
878 retval = dla->sdl_alen;