]> The Tcpdump Group git mirrors - tcpdump/blobdiff - tcpdump.c
Merge remote branch 'origin/master'
[tcpdump] / tcpdump.c
index 7fb72bd91d1dfecb2588236c0bd98c87b597ce41..da88d3837120501d8284ed2b1b446dddcc1ef93a 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -30,7 +30,7 @@ static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
 The Regents of the University of California.  All rights reserved.\n";
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.273 2007-11-21 20:31:31 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.283 2008-09-25 21:45:50 guy Exp $ (LBL)";
 #endif
 
 /*
@@ -90,9 +90,9 @@ extern int SIZE_BUF;
 netdissect_options Gndo;
 netdissect_options *gndo = &Gndo;
 
-int dflag;                     /* print filter code */
-int Lflag;                     /* list available data link types and exit */
-char *zflag = NULL;            /* compress each savefile using a specified command (like gzip or bzip2) */
+static int dflag;                      /* print filter code */
+static int Lflag;                      /* list available data link types and exit */
+static char *zflag = NULL;             /* compress each savefile using a specified command (like gzip or bzip2) */
 
 static int infodelay;
 static int infoprint;
@@ -105,7 +105,7 @@ int32_t thiszone;           /* seconds offset from gmt to local time */
 static RETSIGTYPE cleanup(int);
 static RETSIGTYPE child_cleanup(int);
 static void usage(void) __attribute__((noreturn));
-static void show_dlts_and_exit(pcap_t *pd) __attribute__((noreturn));
+static void show_dlts_and_exit(const char *device, pcap_t *pd) __attribute__((noreturn));
 
 static void print_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
 static void ndo_default_print(netdissect_options *, const u_char *, u_int);
@@ -131,12 +131,21 @@ static void info(int);
 static u_int packets_captured;
 
 typedef u_int (*if_printer)(const struct pcap_pkthdr *, const u_char *);
+typedef u_int (*if_ndo_printer)(struct netdissect_options *ndo,
+                                const struct pcap_pkthdr *, const u_char *);
 
 struct printer {
-       if_printer f;
+        if_printer f;
        int type;
 };
 
+
+struct ndo_printer {
+        if_ndo_printer f;
+       int type;
+};
+
+
 static struct printer printers[] = {
        { arcnet_if_print,      DLT_ARCNET },
 #ifdef DLT_ARCNET_LINUX
@@ -151,7 +160,7 @@ static struct printer printers[] = {
        { cip_if_print,         DLT_CIP },
 #endif
 #ifdef DLT_ATM_CLIP
-       { cip_if_print,         DLT_ATM_CLIP },
+       { cip_if_print,         DLT_ATM_CLIP },
 #endif
        { sl_if_print,          DLT_SLIP },
 #ifdef DLT_SLIP_BSDOS
@@ -178,7 +187,7 @@ static struct printer printers[] = {
        { chdlc_if_print,       DLT_HDLC },
 #endif
 #ifdef DLT_PPP_SERIAL
-       { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
+       { ppp_hdlc_if_print,    DLT_PPP_SERIAL },
 #endif
 #ifdef DLT_PPP_ETHER
        { pppoe_if_print,       DLT_PPP_ETHER },
@@ -193,7 +202,7 @@ static struct printer printers[] = {
        { ltalk_if_print,       DLT_LTALK },
 #endif
 #if defined(DLT_PFLOG) && defined(HAVE_NET_PFVAR_H)
-       { pflog_if_print,       DLT_PFLOG },
+       { pflog_if_print,       DLT_PFLOG },
 #endif
 #ifdef DLT_FR
        { fr_if_print,          DLT_FR },
@@ -214,14 +223,17 @@ static struct printer printers[] = {
        { ieee802_11_radio_if_print,    DLT_IEEE802_11_RADIO },
 #endif
 #ifdef DLT_ENC
-       { enc_if_print,         DLT_ENC },
+       { enc_if_print,         DLT_ENC },
 #endif
 #ifdef DLT_SYMANTEC_FIREWALL
-       { symantec_if_print,    DLT_SYMANTEC_FIREWALL },
+       { symantec_if_print,    DLT_SYMANTEC_FIREWALL },
 #endif
 #ifdef DLT_APPLE_IP_OVER_IEEE1394
        { ap1394_if_print,      DLT_APPLE_IP_OVER_IEEE1394 },
 #endif
+#ifdef DLT_IEEE802_11_RADIO_AVS
+       { ieee802_11_radio_avs_if_print,        DLT_IEEE802_11_RADIO_AVS },
+#endif
 #ifdef DLT_JUNIPER_ATM1
        { juniper_atm1_print,   DLT_JUNIPER_ATM1 },
 #endif
@@ -256,22 +268,46 @@ static struct printer printers[] = {
        { juniper_services_print, DLT_JUNIPER_SERVICES },
 #endif
 #ifdef DLT_JUNIPER_ETHER
-       { juniper_ether_print, DLT_JUNIPER_ETHER },
+       { juniper_ether_print,  DLT_JUNIPER_ETHER },
 #endif
 #ifdef DLT_JUNIPER_PPP
-       { juniper_ppp_print, DLT_JUNIPER_PPP },
+       { juniper_ppp_print,    DLT_JUNIPER_PPP },
 #endif
 #ifdef DLT_JUNIPER_FRELAY
-       { juniper_frelay_print, DLT_JUNIPER_FRELAY },
+       { juniper_frelay_print, DLT_JUNIPER_FRELAY },
 #endif
 #ifdef DLT_JUNIPER_CHDLC
-       { juniper_chdlc_print, DLT_JUNIPER_CHDLC },
+       { juniper_chdlc_print,  DLT_JUNIPER_CHDLC },
 #endif
 #ifdef DLT_MFR
-       { mfr_if_print, DLT_MFR },
+       { mfr_if_print,         DLT_MFR },
+#endif
+#if defined(DLT_BLUETOOTH_HCI_H4_WITH_PHDR) && defined(HAVE_PCAP_BLUETOOTH_H)
+       { bt_if_print,          DLT_BLUETOOTH_HCI_H4_WITH_PHDR},
 #endif
-#ifdef DLT_BLUETOOTH_HCI_H4_WITH_PHDR
-       { bt_if_print, DLT_BLUETOOTH_HCI_H4_WITH_PHDR},
+#ifdef HAVE_PCAP_USB_H
+#ifdef DLT_USB_LINUX
+       { usb_linux_48_byte_print, DLT_USB_LINUX},
+#endif /* DLT_USB_LINUX */
+#ifdef DLT_USB_LINUX_MMAPPED
+       { usb_linux_64_byte_print, DLT_USB_LINUX_MMAPPED},
+#endif /* DLT_USB_LINUX_MMAPPED */
+#endif /* HAVE_PCAP_USB_H */
+#ifdef DLT_IPV4
+       { raw_if_print,         DLT_IPV4 },
+#endif
+#ifdef DLT_IPV6
+       { raw_if_print,         DLT_IPV6 },
+#endif
+       { NULL,                 0 },
+};
+
+static struct ndo_printer ndo_printers[] = {
+#ifdef DLT_IPNET
+       { ipnet_if_print,       DLT_IPNET },
+#endif
+#ifdef DLT_IEEE802_15_4
+       { ieee802_15_4_if_print, DLT_IEEE802_15_4 },
 #endif
        { NULL,                 0 },
 };
@@ -289,14 +325,34 @@ lookup_printer(int type)
        /* NOTREACHED */
 }
 
+static if_ndo_printer
+lookup_ndo_printer(int type)
+{
+       struct ndo_printer *p;
+
+       for (p = ndo_printers; p->f; ++p)
+               if (type == p->type)
+                       return p->f;
+
+       return NULL;
+       /* NOTREACHED */
+}
+
 static pcap_t *pd;
 
+static int supports_monitor_mode;
+
 extern int optind;
 extern int opterr;
 extern char *optarg;
 
 struct print_info {
-       if_printer printer;
+        netdissect_options *ndo;
+        union {
+                if_printer     printer;
+                if_ndo_printer ndo_printer;
+        } p;
+        int ndo_type;
 };
 
 struct dump_info {
@@ -307,7 +363,7 @@ struct dump_info {
 };
 
 static void
-show_dlts_and_exit(pcap_t *pd)
+show_dlts_and_exit(const char *device, pcap_t *pd)
 {
        int n_dlts;
        int *dlts = 0;
@@ -319,7 +375,21 @@ show_dlts_and_exit(pcap_t *pd)
        else if (n_dlts == 0 || !dlts)
                error("No data link types.");
 
-       (void) fprintf(stderr, "Data link types (use option -y to set):\n");
+       /*
+        * If the interface is known to support monitor mode, indicate
+        * whether these are the data link types available when not in
+        * monitor mode, if -I wasn't specified, or when in monitor mode,
+        * when -I was specified (the link-layer types available in
+        * monitor mode might be different from the ones available when
+        * not in monitor mode).
+        */
+       if (supports_monitor_mode)
+               (void) fprintf(stderr, "Data link types for %s %s (use option -y to set):\n",
+                   device,
+                   Iflag ? "when in monitor mode" : "when not in monitor mode");
+       else
+               (void) fprintf(stderr, "Data link types for %s (use option -y to set):\n",
+                   device);
 
        while (--n_dlts >= 0) {
                dlt_name = pcap_datalink_val_to_name(dlts[n_dlts]);
@@ -330,11 +400,12 @@ show_dlts_and_exit(pcap_t *pd)
                        /*
                         * OK, does tcpdump handle that type?
                         */
-                       if (lookup_printer(dlts[n_dlts]) == NULL)
-                               (void) fprintf(stderr, " (not supported)");
+                       if (lookup_printer(dlts[n_dlts]) == NULL
+                            && lookup_ndo_printer(dlts[n_dlts]) == NULL)
+                               (void) fprintf(stderr, " (printing not supported)");
                        putchar('\n');
                } else {
-                       (void) fprintf(stderr, "  DLT %d (not supported)\n",
+                       (void) fprintf(stderr, "  DLT %d (printing not supported)\n",
                            dlts[n_dlts]);
                }
        }
@@ -346,13 +417,19 @@ show_dlts_and_exit(pcap_t *pd)
  * Set up flags that might or might not be supported depending on the
  * version of libpcap we're using.
  */
-#ifdef WIN32
+#if defined(HAVE_PCAP_CREATE) || defined(WIN32)
 #define B_FLAG         "B:"
 #define B_FLAG_USAGE   " [ -B size ]"
-#else /* WIN32 */
+#else /* defined(HAVE_PCAP_CREATE) || defined(WIN32) */
 #define B_FLAG
 #define B_FLAG_USAGE
-#endif /* WIN32 */
+#endif /* defined(HAVE_PCAP_CREATE) || defined(WIN32) */
+
+#ifdef HAVE_PCAP_CREATE
+#define I_FLAG         "I"
+#else /* HAVE_PCAP_CREATE */
+#define I_FLAG
+#endif /* HAVE_PCAP_CREATE */
 
 #ifdef HAVE_PCAP_FINDALLDEVS
 #ifndef HAVE_PCAP_IF_T
@@ -495,7 +572,6 @@ main(int argc, char **argv)
 #endif
        int status;
 #ifdef WIN32
-       u_int UserBufferSize = 1000000;
        if(wsockinit() != 0) return 1;
 #endif /* WIN32 */
 
@@ -527,7 +603,7 @@ main(int argc, char **argv)
 
        opterr = 0;
        while (
-           (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:KlLm:M:nNOpqr:Rs:StT:u" U_FLAG "vw:W:xXy:Yz:Z:")) != -1)
+           (op = getopt(argc, argv, "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:" I_FLAG "KlLm:M:nNOpqr:Rs:StT:u" U_FLAG "vw:W:xXy:Yz:Z:")) != -1)
                switch (op) {
 
                case 'a':
@@ -538,13 +614,17 @@ main(int argc, char **argv)
                        ++Aflag;
                        break;
 
-#ifdef WIN32
+               case 'b':
+                       ++bflag;
+                       break;
+
+#if defined(HAVE_PCAP_CREATE) || defined(WIN32)
                case 'B':
-                       UserBufferSize = atoi(optarg)*1024;
-                       if (UserBufferSize < 0)
+                       Bflag = atoi(optarg)*1024;
+                       if (Bflag <= 0)
                                error("invalid packet buffer size %s", optarg);
                        break;
-#endif /* WIN32 */
+#endif /* defined(HAVE_PCAP_CREATE) || defined(WIN32) */
 
                case 'c':
                        cnt = atoi(optarg);
@@ -638,11 +718,17 @@ main(int argc, char **argv)
                                if (pcap_findalldevs(&devpointer, ebuf) < 0)
                                        error("%s", ebuf);
                                else {
-                                       for (i = 0; i < devnum-1; i++){
-                                               devpointer = devpointer->next;
-                                               if (devpointer == NULL)
-                                                       error("Invalid adapter index");
-                                       }
+                                       /*
+                                        * Look for the devnum-th entry
+                                        * in the list of devices
+                                        * (1-based).
+                                        */
+                                       for (i = 0;
+                                           i < devnum-1 && devpointer != NULL;
+                                           i++, devpointer = devpointer->next)
+                                               ;
+                                       if (devpointer == NULL)
+                                               error("Invalid adapter index");
                                }
                                device = devpointer->name;
                                break;
@@ -651,6 +737,12 @@ main(int argc, char **argv)
                        device = optarg;
                        break;
 
+#ifdef HAVE_PCAP_CREATE
+               case 'I':
+                       ++Iflag;
+                       break;
+#endif /* HAVE_PCAP_CREATE */
+
                case 'l':
 #ifdef WIN32
                        /*
@@ -694,7 +786,7 @@ main(int argc, char **argv)
 #ifndef HAVE_LIBCRYPTO
                        warning("crypto code not compiled in");
 #endif
-                       tcpmd5secret = optarg;
+                       sigsecret = optarg;
                        break;
 
                case 'n':
@@ -731,10 +823,10 @@ main(int argc, char **argv)
 
                        snaplen = strtol(optarg, &end, 0);
                        if (optarg == end || *end != '\0'
-                           || snaplen < 0 || snaplen > 65535)
+                           || snaplen < 0 || snaplen > MAXIMUM_SNAPLEN)
                                error("invalid snaplen %s", optarg);
                        else if (snaplen == 0)
-                               snaplen = 65535;
+                               snaplen = MAXIMUM_SNAPLEN;
                        break;
                }
 
@@ -939,12 +1031,81 @@ main(int argc, char **argv)
 
                fflush(stderr); 
 #endif /* WIN32 */
+#ifdef HAVE_PCAP_CREATE
+               pd = pcap_create(device, ebuf);
+               if (pd == NULL)
+                       error("%s", ebuf);
+               /*
+                * Is this an interface that supports monitor mode?
+                */
+               if (pcap_can_set_rfmon(pd) == 1)
+                       supports_monitor_mode = 1;
+               else
+                       supports_monitor_mode = 0;
+               status = pcap_set_snaplen(pd, snaplen);
+               if (status != 0)
+                       error("%s: pcap_set_snaplen failed: %s",
+                           device, pcap_statustostr(status));
+               status = pcap_set_promisc(pd, !pflag);
+               if (status != 0)
+                       error("%s: pcap_set_promisc failed: %s",
+                           device, pcap_statustostr(status));
+               if (Iflag) {
+                       status = pcap_set_rfmon(pd, 1);
+                       if (status != 0)
+                               error("%s: pcap_set_rfmon failed: %s",
+                                   device, pcap_statustostr(status));
+               }
+               status = pcap_set_timeout(pd, 1000);
+               if (status != 0)
+                       error("%s: pcap_set_timeout failed: %s",
+                           device, pcap_statustostr(status));
+               if (Bflag != 0) {
+                       status = pcap_set_buffer_size(pd, Bflag);
+                       if (status != 0)
+                               error("%s: pcap_set_buffer_size failed: %s",
+                                   device, pcap_statustostr(status));
+               }
+               status = pcap_activate(pd);
+               if (status < 0) {
+                       /*
+                        * pcap_activate() failed.
+                        */
+                       cp = pcap_geterr(pd);
+                       if (status == PCAP_ERROR)
+                               error("%s", cp);
+                       else if ((status == PCAP_ERROR_NO_SUCH_DEVICE ||
+                                 status == PCAP_ERROR_PERM_DENIED) &&
+                                *cp != '\0')
+                               error("%s: %s\n(%s)", device,
+                                   pcap_statustostr(status), cp);
+                       else
+                               error("%s: %s", device,
+                                   pcap_statustostr(status));
+               } else if (status > 0) {
+                       /*
+                        * pcap_activate() succeeded, but it's warning us
+                        * of a problem it had.
+                        */
+                       cp = pcap_geterr(pd);
+                       if (status == PCAP_WARNING)
+                               warning("%s", cp);
+                       else if (status == PCAP_WARNING_PROMISC_NOTSUP &&
+                                *cp != '\0')
+                               warning("%s: %s\n(%s)", device,
+                                   pcap_statustostr(status), cp);
+                       else
+                               warning("%s: %s", device,
+                                   pcap_statustostr(status));
+               }
+#else
                *ebuf = '\0';
                pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
                if (pd == NULL)
                        error("%s", ebuf);
                else if (*ebuf)
                        warning("%s", ebuf);
+#endif /* HAVE_PCAP_CREATE */
                /*
                 * Let user own process after socket has been opened.
                 */
@@ -952,14 +1113,14 @@ main(int argc, char **argv)
                if (setgid(getgid()) != 0 || setuid(getuid()) != 0)
                        fprintf(stderr, "Warning: setgid/setuid failed !\n");
 #endif /* WIN32 */
-#ifdef WIN32
-               if(UserBufferSize != 1000000)
-                       if(pcap_setbuff(pd, UserBufferSize)==-1){
+#if !defined(HAVE_PCAP_CREATE) && defined(WIN32)
+               if(Bflag != 0)
+                       if(pcap_setbuff(pd, Bflag)==-1){
                                error("%s", pcap_geterr(pd));
                        }
-#endif /* WIN32 */
+#endif /* !defined(HAVE_PCAP_CREATE) && defined(WIN32) */
                if (Lflag)
-                       show_dlts_and_exit(pd);
+                       show_dlts_and_exit(device, pd);
                if (gndo->ndo_dlt >= 0) {
 #ifdef HAVE_PCAP_SET_DATALINK
                        if (pcap_set_datalink(pd, gndo->ndo_dlt) < 0)
@@ -997,6 +1158,7 @@ main(int argc, char **argv)
 
        if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
                error("%s", pcap_geterr(pd));
+       free(cmdbuf);
        if (dflag) {
                bpf_dump(&fcode, dflag);
                pcap_close(pd);
@@ -1048,15 +1210,21 @@ main(int argc, char **argv)
                }
        } else {
                type = pcap_datalink(pd);
-               printinfo.printer = lookup_printer(type);
-               if (printinfo.printer == NULL) {
-                       gndo->ndo_dltname = pcap_datalink_val_to_name(type);
-                       if (gndo->ndo_dltname != NULL)
-                               error("unsupported data link type %s",
-                                     gndo->ndo_dltname);
-                       else
-                               error("unsupported data link type %d", type);
-               }
+                printinfo.ndo_type = 1;
+                printinfo.ndo = gndo;
+               printinfo.p.ndo_printer = lookup_ndo_printer(type);
+                if (printinfo.p.ndo_printer == NULL) {
+                        printinfo.p.printer = lookup_printer(type);
+                        printinfo.ndo_type = 0;
+                        if (printinfo.p.printer == NULL) {
+                                gndo->ndo_dltname = pcap_datalink_val_to_name(type);
+                                if (gndo->ndo_dltname != NULL)
+                                        error("packet printing is not supported for link type %s: use -w",
+                                              gndo->ndo_dltname);
+                                else
+                                        error("packet printing is not supported for link type %d: use -w", type);
+                        }
+                }
                callback = print_packet;
                pcap_userdata = (u_char *)&printinfo;
        }
@@ -1071,7 +1239,12 @@ main(int argc, char **argv)
        }
 #endif /* WIN32 */
 #ifdef SIGINFO
-       (void)setsignal(SIGINFO, requestinfo);
+       /*
+        * We can't get statistics when reading from a file rather
+        * than capturing from a device.
+        */
+       if (RFileName == NULL)
+               (void)setsignal(SIGINFO, requestinfo);
 #endif
 
        if (vflag > 0 && WFileName) {
@@ -1206,6 +1379,11 @@ info(register int verbose)
 {
        struct pcap_stat stat;
 
+       /*
+        * Older versions of libpcap didn't set ps_ifdrop on some
+        * platforms; initialize it to 0 to handle that.
+        */
+       stat.ps_ifdrop = 0;
        if (pcap_stats(pd, &stat) < 0) {
                (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
                infoprint = 0;
@@ -1220,12 +1398,21 @@ info(register int verbose)
                fputs(", ", stderr);
        else
                putc('\n', stderr);
-       (void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
+       (void)fprintf(stderr, "%u packets received by filter", stat.ps_recv);
        if (!verbose)
                fputs(", ", stderr);
        else
                putc('\n', stderr);
-       (void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
+       (void)fprintf(stderr, "%u packets dropped by kernel", stat.ps_drop);
+       if (stat.ps_ifdrop != 0) {
+               if (!verbose)
+                       fputs(", ", stderr);
+               else
+                       putc('\n', stderr);
+               (void)fprintf(stderr, "%u packets dropped by interface\n",
+                   stat.ps_ifdrop);
+       } else
+               putc('\n', stderr);
        infoprint = 0;
 }
 
@@ -1243,7 +1430,7 @@ compress_savefile(const char *filename)
 #else
        setpriority(PRIO_PROCESS, 0, 19);
 #endif
-       if (execlp(zflag, zflag, filename, NULL) == -1)
+       if (execlp(zflag, zflag, filename, (char *)NULL) == -1)
                fprintf(stderr,
                        "compress_savefile:execlp(%s, %s): %s\n",
                        zflag,
@@ -1421,7 +1608,12 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
         */
        snapend = sp + h->caplen;
 
-       hdrlen = (*print_info->printer)(h, sp);
+        if(print_info->ndo_type) {
+                hdrlen = (*print_info->p.ndo_printer)(print_info->ndo, h, sp);
+        } else {
+                hdrlen = (*print_info->p.printer)(h, sp);
+        }
+                
        if (Xflag) {
                /*
                 * Print the raw packet data in hex and ASCII.
@@ -1591,13 +1783,15 @@ usage(void)
 #endif /* WIN32 */
 #endif /* HAVE_PCAP_LIB_VERSION */
        (void)fprintf(stderr,
-"Usage: %s [-aAd" D_FLAG "efKlLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [-c count] [ -C file_size ]\n", program_name);
+"Usage: %s [-aAbd" D_FLAG "ef" I_FLAG "KlLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [ -c count ]\n", program_name);
        (void)fprintf(stderr,
-"\t\t[ -E algo:secret ] [ -F file ] [ -G seconds ] [ -i interface ]\n");
+"\t\t[ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]\n");
        (void)fprintf(stderr,
-"\t\t[ -M secret ] [ -r file ] [ -s snaplen ] [ -T type ] [ -w file ]\n");
+"\t\t[ -i interface ] [ -M secret ] [ -r file ]\n");
        (void)fprintf(stderr,
-"\t\t[ -W filecount ] [ -y datalinktype ] [ -z command ] [ -Z user ]\n");
+"\t\t[ -s snaplen ] [ -T type ] [ -w file ] [ -W filecount ]\n");
+       (void)fprintf(stderr,
+"\t\t[ -y datalinktype ] [ -z command ] [ -Z user ]\n");
        (void)fprintf(stderr,
 "\t\t[ expression ]\n");
        exit(1);
@@ -1640,4 +1834,3 @@ ndo_warning(netdissect_options *ndo _U_, const char *fmt, ...)
                        (void)fputc('\n', stderr);
        }
 }
-