2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1984, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Sun Microsystems, Inc.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 static char const copyright[] =
38 "@(#) Copyright (c) 1984, 1993\n\
39 The Regents of the University of California. All rights reserved.\n";
43 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
50 * arp - display, set, and delete arp table entries
53 #include <sys/param.h>
55 #include <sys/socket.h>
56 #include <sys/sockio.h>
57 #include <sys/sysctl.h>
58 #include <sys/ioctl.h>
62 #include <net/if_dl.h>
63 #include <net/if_types.h>
64 #include <net/route.h>
66 #include <netinet/in.h>
67 #include <netinet/if_ether.h>
69 #include <arpa/inet.h>
85 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in,
86 struct rt_msghdr *rtm);
88 static int search(u_long addr, action_fn *action);
89 static action_fn print_entry;
90 static action_fn nuke_entry;
92 static int delete(char *host);
93 static void usage(void);
94 static int set(int argc, char **argv);
95 static int get(char *host);
96 static int file(char *name);
97 static struct rt_msghdr *rtmsg(int cmd,
98 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
99 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
100 static struct sockaddr_in *getaddr(char *host);
101 static int valid_type(int type);
103 static int nflag; /* no reverse dns lookups */
104 static char *rifname;
106 static time_t expire_time;
107 static int flags, doing_proxy;
109 struct if_nameindex *ifnameindex;
111 /* which function we're supposed to do */
118 #define SETFUNC(f) { if (func) usage(); func = (f); }
120 #define ARP_XO_VERSION "1"
123 main(int argc, char *argv[])
127 int aflag = 0; /* do it for all entries */
129 argc = xo_parse_args(argc, argv);
133 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
166 if (func != F_GET && !(func == F_DELETE && aflag))
167 xo_errx(1, "-i not applicable to this operation");
168 if (if_nametoindex(rifname) == 0) {
170 xo_errx(1, "interface %s does not exist",
173 xo_err(1, "if_nametoindex(%s)", rifname);
182 xo_set_version(ARP_XO_VERSION);
183 xo_open_container("arp");
184 xo_open_list("arp-cache");
186 search(0, print_entry);
188 xo_close_list("arp-cache");
189 xo_close_container("arp");
199 if (argc < 2 || argc > 6)
201 if (func == F_REPLACE)
202 (void)delete(argv[0]);
203 rtn = set(argc, argv) ? 1 : 0;
209 search(0, nuke_entry);
213 rtn = delete(argv[0]);
223 if (ifnameindex != NULL)
224 if_freenameindex(ifnameindex);
230 * Process a file to set standard arp entries
237 char line[100], arg[5][50], *args[5], *p;
239 if ((fp = fopen(name, "r")) == NULL)
240 xo_err(1, "cannot open %s", name);
241 args[0] = &arg[0][0];
242 args[1] = &arg[1][0];
243 args[2] = &arg[2][0];
244 args[3] = &arg[3][0];
245 args[4] = &arg[4][0];
247 while(fgets(line, sizeof(line), fp) != NULL) {
248 if ((p = strchr(line, '#')) != NULL)
250 for (p = line; isblank(*p); p++);
251 if (*p == '\n' || *p == '\0')
253 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
254 arg[2], arg[3], arg[4]);
256 xo_warnx("bad line: %s", line);
268 * Given a hostname, fills up a (static) struct sockaddr_in with
269 * the address of the host and returns a pointer to the
272 static struct sockaddr_in *
276 static struct sockaddr_in reply;
278 bzero(&reply, sizeof(reply));
279 reply.sin_len = sizeof(reply);
280 reply.sin_family = AF_INET;
281 reply.sin_addr.s_addr = inet_addr(host);
282 if (reply.sin_addr.s_addr == INADDR_NONE) {
283 if (!(hp = gethostbyname(host))) {
284 xo_warnx("%s: %s", host, hstrerror(h_errno));
287 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
288 sizeof reply.sin_addr);
294 * Returns true if the type is a valid one for ARP.
316 * Set an individual arp entry
319 set(int argc, char **argv)
321 struct sockaddr_in *addr;
322 struct sockaddr_in *dst; /* what are we looking for */
323 struct sockaddr_dl *sdl;
324 struct rt_msghdr *rtm;
325 struct ether_addr *ea;
326 char *host = argv[0], *eaddr = argv[1];
327 struct sockaddr_dl sdl_m;
332 bzero(&sdl_m, sizeof(sdl_m));
333 sdl_m.sdl_len = sizeof(sdl_m);
334 sdl_m.sdl_family = AF_LINK;
339 doing_proxy = flags = expire_time = 0;
341 if (strcmp(argv[0], "temp") == 0) {
344 size_t len = sizeof(max_age);
346 clock_gettime(CLOCK_MONOTONIC, &tp);
347 if (sysctlbyname("net.link.ether.inet.max_age",
348 &max_age, &len, NULL, 0) != 0)
349 xo_err(1, "sysctlbyname");
350 expire_time = tp.tv_sec + max_age;
351 } else if (strcmp(argv[0], "pub") == 0) {
352 flags |= RTF_ANNOUNCE;
354 if (argc && strcmp(argv[1], "only") == 0) {
356 * Compatibility: in pre FreeBSD 8 times
357 * the "only" keyword used to mean that
358 * an ARP entry should be announced, but
359 * not installed into routing table.
363 } else if (strcmp(argv[0], "blackhole") == 0) {
364 if (flags & RTF_REJECT) {
365 xo_errx(1, "Choose one of blackhole or reject, "
368 flags |= RTF_BLACKHOLE;
369 } else if (strcmp(argv[0], "reject") == 0) {
370 if (flags & RTF_BLACKHOLE) {
371 xo_errx(1, "Choose one of blackhole or reject, "
376 xo_warnx("Invalid parameter '%s'", argv[0]);
381 ea = (struct ether_addr *)LLADDR(&sdl_m);
382 if (doing_proxy && !strcmp(eaddr, "auto")) {
383 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
384 xo_warnx("no interface found for %s",
385 inet_ntoa(dst->sin_addr));
388 sdl_m.sdl_alen = ETHER_ADDR_LEN;
390 struct ether_addr *ea1 = ether_aton(eaddr);
393 xo_warnx("invalid Ethernet address '%s'", eaddr);
397 sdl_m.sdl_alen = ETHER_ADDR_LEN;
402 * In the case a proxy-arp entry is being added for
403 * a remote end point, the RTF_ANNOUNCE flag in the
404 * RTM_GET command is an indication to the kernel
405 * routing code that the interface associated with
406 * the prefix route covering the local end of the
407 * PPP link should be returned, on which ARP applies.
409 rtm = rtmsg(RTM_GET, dst, NULL);
414 addr = (struct sockaddr_in *)(rtm + 1);
415 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
417 if ((sdl->sdl_family != AF_LINK) ||
418 (rtm->rtm_flags & RTF_GATEWAY) ||
419 !valid_type(sdl->sdl_type)) {
420 xo_warnx("cannot intuit interface index and type for %s", host);
423 sdl_m.sdl_type = sdl->sdl_type;
424 sdl_m.sdl_index = sdl->sdl_index;
425 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
429 * Display an individual arp entry
434 struct sockaddr_in *addr;
437 addr = getaddr(host);
441 xo_set_version(ARP_XO_VERSION);
442 xo_open_container("arp");
443 xo_open_list("arp-cache");
445 found = search(addr->sin_addr.s_addr, print_entry);
448 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry",
449 host, inet_ntoa(addr->sin_addr));
451 xo_emit(" on {d:interface/%s}", rifname);
455 xo_close_list("arp-cache");
456 xo_close_container("arp");
463 * Delete an arp entry
468 struct sockaddr_in *addr, *dst;
469 struct rt_msghdr *rtm;
470 struct sockaddr_dl *sdl;
477 * Perform a regular entry delete first.
479 flags &= ~RTF_ANNOUNCE;
481 for (;;) { /* try twice */
482 rtm = rtmsg(RTM_GET, dst, NULL);
487 addr = (struct sockaddr_in *)(rtm + 1);
488 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
491 * With the new L2/L3 restructure, the route
492 * returned is a prefix route. The important
493 * piece of information from the previous
494 * RTM_GET is the interface index. In the
495 * case of ECMP, the kernel will traverse
496 * the route group for the given entry.
498 if (sdl->sdl_family == AF_LINK &&
499 !(rtm->rtm_flags & RTF_GATEWAY) &&
500 valid_type(sdl->sdl_type) ) {
501 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
506 * Regular entry delete failed, now check if there
507 * is a proxy-arp entry to remove.
509 if (flags & RTF_ANNOUNCE) {
510 xo_warnx("delete: cannot locate %s", host);
514 flags |= RTF_ANNOUNCE;
516 rtm->rtm_flags |= RTF_LLDATA;
517 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
518 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
526 * Search the arp table and do some action on matching entries
529 search(u_long addr, action_fn *action)
533 char *lim, *buf, *next;
534 struct rt_msghdr *rtm;
535 struct sockaddr_in *sin2;
536 struct sockaddr_dl *sdl;
537 char ifname[IF_NAMESIZE];
538 int st, found_entry = 0;
544 mib[4] = NET_RT_FLAGS;
550 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
551 xo_err(1, "route-sysctl-estimate");
552 if (needed == 0) /* empty table */
556 buf = reallocf(buf, needed);
558 xo_errx(1, "could not reallocate memory");
559 st = sysctl(mib, 6, buf, &needed, NULL, 0);
560 if (st == 0 || errno != ENOMEM)
562 needed += needed / 8;
565 xo_err(1, "actual retrieval of routing table");
567 for (next = buf; next < lim; next += rtm->rtm_msglen) {
568 rtm = (struct rt_msghdr *)next;
569 sin2 = (struct sockaddr_in *)(rtm + 1);
570 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
571 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
572 strcmp(ifname, rifname))
575 if (addr != sin2->sin_addr.s_addr)
579 (*action)(sdl, sin2, rtm);
582 return (found_entry);
586 * Display an arp entry
590 print_entry(struct sockaddr_dl *sdl,
591 struct sockaddr_in *addr, struct rt_msghdr *rtm)
595 struct if_nameindex *p;
597 if (ifnameindex == NULL)
598 if ((ifnameindex = if_nameindex()) == NULL)
599 xo_err(1, "cannot retrieve interface names");
601 xo_open_instance("arp-cache");
604 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
605 sizeof addr->sin_addr, AF_INET);
612 if (h_errno == TRY_AGAIN)
615 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host,
616 inet_ntoa(addr->sin_addr));
618 if ((sdl->sdl_type == IFT_ETHER ||
619 sdl->sdl_type == IFT_L2VLAN ||
620 sdl->sdl_type == IFT_BRIDGE) &&
621 sdl->sdl_alen == ETHER_ADDR_LEN)
622 xo_emit("{:mac-address/%s}",
623 ether_ntoa((struct ether_addr *)LLADDR(sdl)));
625 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
627 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n);
630 xo_emit("{d:/(incomplete)}{en:incomplete/true}");
632 for (p = ifnameindex; p && p->if_index && p->if_name; p++) {
633 if (p->if_index == sdl->sdl_index) {
634 xo_emit(" on {:interface/%s}", p->if_name);
639 if (rtm->rtm_rmx.rmx_expire == 0)
640 xo_emit("{d:/ permanent}{en:permanent/true}");
642 static struct timespec tp;
644 clock_gettime(CLOCK_MONOTONIC, &tp);
645 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
646 xo_emit(" expires in {:expires/%d} seconds",
649 xo_emit("{d:/ expired}{en:expired/true}");
652 if (rtm->rtm_flags & RTF_ANNOUNCE)
653 xo_emit("{d:/ published}{en:published/true}");
655 switch(sdl->sdl_type) {
657 xo_emit(" [{:type/ethernet}]");
660 xo_emit(" [{:type/fddi}]");
663 xo_emit(" [{:type/atm}]");
666 xo_emit(" [{:type/vlan}]");
669 xo_emit(" [{:type/firewire}]");
672 xo_emit(" [{:type/bridge}]");
675 xo_emit(" [{:type/infiniband}]");
683 xo_close_instance("arp-cache");
690 nuke_entry(struct sockaddr_dl *sdl __unused,
691 struct sockaddr_in *addr, struct rt_msghdr *rtm)
695 if (rtm->rtm_flags & RTF_PINNED)
698 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
705 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
706 "usage: arp [-n] [-i interface] hostname",
707 " arp [-n] [-i interface] -a",
708 " arp -d hostname [pub]",
709 " arp -d [-i interface] -a",
710 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
711 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
716 static struct rt_msghdr *
717 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
726 struct rt_msghdr m_rtm;
730 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
731 char *cp = m_rtmsg.m_space;
733 if (s < 0) { /* first time: open socket, get pid */
734 s = socket(PF_ROUTE, SOCK_RAW, 0);
742 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
745 if (cmd == RTM_DELETE)
747 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
748 rtm->rtm_flags = flags;
749 rtm->rtm_version = RTM_VERSION;
753 xo_errx(1, "internal wrong cmd");
755 rtm->rtm_addrs |= RTA_GATEWAY;
756 rtm->rtm_rmx.rmx_expire = expire_time;
757 rtm->rtm_inits = RTV_EXPIRE;
758 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
761 rtm->rtm_addrs |= RTA_DST;
763 #define NEXTADDR(w, s) \
765 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
766 bcopy((s), cp, sizeof(*(s))); \
771 NEXTADDR(RTA_DST, dst);
772 NEXTADDR(RTA_GATEWAY, sdl);
774 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
777 rtm->rtm_seq = ++seq;
779 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
780 if (errno != ESRCH || cmd != RTM_DELETE) {
781 xo_warn("writing to routing socket");
786 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
787 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq ||
788 rtm->rtm_pid != pid));
790 xo_warn("read from routing socket");
795 * get_ether_addr - get the hardware address of an interface on the
796 * the same subnet as ipaddr.
799 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
801 struct ifaddrs *ifa, *ifd, *ifas = NULL;
803 struct sockaddr_dl *dla;
807 * Scan through looking for an interface with an Internet
808 * address on the same subnet as `ipaddr'.
810 if (getifaddrs(&ifas) < 0) {
811 xo_warnx("getifaddrs");
815 for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) {
816 if (ifa->ifa_addr == NULL || ifa->ifa_netmask == NULL)
818 if (ifa->ifa_addr->sa_family != AF_INET)
821 * Check that the interface is up,
822 * and not point-to-point or loopback.
824 if ((ifa->ifa_flags &
825 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
826 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST))
828 /* Get its netmask and check that it's on the right subnet. */
829 mask = ((struct sockaddr_in *)
830 ifa->ifa_netmask)->sin_addr.s_addr;
831 ina = ((struct sockaddr_in *)
832 ifa->ifa_addr)->sin_addr.s_addr;
833 if ((ipaddr & mask) == (ina & mask))
834 break; /* ok, we got it! */
840 * Now scan through again looking for a link-level address
841 * for this interface.
843 for (ifd = ifas; ifd != NULL; ifd = ifd->ifa_next) {
844 if (ifd->ifa_addr == NULL)
846 if (strcmp(ifa->ifa_name, ifd->ifa_name) == 0 &&
847 ifd->ifa_addr->sa_family == AF_LINK)
853 * Found the link-level address - copy it out
855 dla = (struct sockaddr_dl *)ifd->ifa_addr;
856 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
857 printf("using interface %s for proxy with address %s\n", ifa->ifa_name,
859 retval = dla->sdl_alen;