/* packet-ntp.c * Routines for NTP packet dissection * Copyright 1999, Nathan Neulinger * * $Id: packet-ntp.c,v 1.35 2002/04/02 01:32:46 guy Exp $ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * Copied from packet-tftp.c * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #ifdef HAVE_SYS_TYPES_H # include #endif #ifdef HAVE_NETINET_IN_H # include #endif #include #include #include #include #ifdef NEED_SNPRINTF_H # include "snprintf.h" #endif #include #include #include "packet-ntp.h" /* * Dissecting NTP packets version 3 and 4 (RFC2030, RFC1769, RFC1361, * RFC1305). * * Those packets have simple structure: * 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |LI | VN |Mode | Stratum | Poll | Precision | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Root Delay | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Root Dispersion | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Reference Identifier | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Reference Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Originate Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Receive Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Transmit Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Key Identifier (optional) (32) | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Message Digest (optional) (128) | * | | * | | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * NTP timestamps are represented as a 64-bit unsigned fixed-point number, * in seconds relative to 0h on 1 January 1900. The integer part is in the * first 32 bits and the fraction part in the last 32 bits. */ #define UDP_PORT_NTP 123 #define TCP_PORT_NTP 123 /* Leap indicator, 2bit field is used to warn of a inserted/deleted * second, or to alarm loosed synchronization. */ #define NTP_LI_MASK 0xC0 #define NTP_LI_NONE 0 #define NTP_LI_61 1 #define NTP_LI_59 2 #define NTP_LI_ALARM 3 static const value_string li_types[] = { { NTP_LI_NONE, "no warning" }, { NTP_LI_61, "last minute has 61 seconds" }, { NTP_LI_59, "last minute has 59 seconds" }, { NTP_LI_ALARM, "alarm condition (clock not synchronized)" }, { 0, NULL} }; /* Version info, 3bit field informs about NTP version used in particular * packet. According to rfc2030, version info could be only 3 or 4, but I * have noticed packets with 1 or even 6 as version numbers. They are * produced as a result of ntptrace command. Are those packets mailformed * on purpose? I don't know yet, probably some browsing through ntp sources * would help. My solution is to put them as reserved for now. */ #define NTP_VN_MASK 0x38 static const value_string ver_nums[] = { { 0, "reserved" }, { 1, "reserved" }, { 2, "reserved" }, { 3, "NTP Version 3" }, { 4, "NTP Version 4" }, { 5, "reserved" }, { 6, "reserved" }, { 7, "reserved" }, { 0, NULL} }; /* Mode, 3bit field representing mode of comunication. */ #define NTP_MODE_MASK 7 #define NTP_MODE_RSV 0 #define NTP_MODE_SYMACT 1 #define NTP_MODE_SYMPAS 2 #define NTP_MODE_CLIENT 3 #define NTP_MODE_SERVER 4 #define NTP_MODE_BCAST 5 #define NTP_MODE_CTRL 6 #define NTP_MODE_PRIV 7 static const value_string mode_types[] = { { NTP_MODE_RSV, "reserved" }, { NTP_MODE_SYMACT, "symmetric active" }, { NTP_MODE_SYMPAS, "symmetric passive" }, { NTP_MODE_CLIENT, "client" }, { NTP_MODE_SERVER, "server" }, { NTP_MODE_BCAST, "broadcast" }, { NTP_MODE_CTRL, "reserved for NTP control message"}, { NTP_MODE_PRIV, "reserved for private use" }, { 0, NULL} }; /* According to rfc, primary (stratum-0 and stratum-1) servers should set * their Reference Clock ID (4bytes field) according to following table: */ static const struct { char *id; char *data; } primary_sources[] = { { "LOCL", "uncalibrated local clock" }, { "PPS\0", "atomic clock or other pulse-per-second source" }, { "ACTS", "NIST dialup modem service" }, { "USNO", "USNO modem service" }, { "PTB\0", "PTB (Germany) modem service" }, { "TDF\0", "Allouis (France) Radio 164 kHz" }, { "DCF\0", "Mainflingen (Germany) Radio 77.5 kHz" }, { "MSF\0", "Rugby (UK) Radio 60 kHz" }, { "WWV\0", "Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz" }, { "WWVB", "Boulder (US) Radio 60 kHz" }, { "WWVH", "Kaui Hawaii (US) Radio 2.5, 5, 10, 15 MHz" }, { "CHU\0", "Ottawa (Canada) Radio 3330, 7335, 14670 kHz" }, { "LORC", "LORAN-C radionavigation system" }, { "OMEG", "OMEGA radionavigation system" }, { "GPS\0", "Global Positioning Service" }, { "GOES", "Geostationary Orbit Environment Satellite" }, { "DCN\0", "DCN routing protocol" }, { "NIST", "NIST public modem" }, { "TSP\0", "TSP time protocol" }, { "DTS\0", "Digital Time Service" }, { "ATOM", "Atomic clock (calibrated)" }, { "VLF\0", "VLF radio (OMEGA,, etc.)" }, { "IRIG", "IRIG-B timecode" }, { "1PPS", "External 1 PPS input" }, { "FREE", "(Internal clock)" }, { NULL, NULL} }; static int proto_ntp = -1; static int hf_ntp_flags = -1; static int hf_ntp_flags_li = -1; static int hf_ntp_flags_vn = -1; static int hf_ntp_flags_mode = -1; static int hf_ntp_stratum = -1; static int hf_ntp_ppoll = -1; static int hf_ntp_precision = -1; static int hf_ntp_rootdelay = -1; static int hf_ntp_rootdispersion = -1; static int hf_ntp_refid = -1; static int hf_ntp_reftime = -1; static int hf_ntp_org = -1; static int hf_ntp_rec = -1; static int hf_ntp_xmt = -1; static int hf_ntp_keyid = -1; static int hf_ntp_mac = -1; static gint ett_ntp = -1; static gint ett_ntp_flags = -1; /* ntp_fmt_ts - converts NTP timestamp to human readable string. * reftime - 64bit timestamp (IN) * buff - string buffer for result (OUT) * returns pointer to filled buffer. */ static char * ntp_fmt_ts(const guint8 *reftime, char* buff) { guint32 tempstmp, tempfrac; time_t temptime; struct tm *bd; double fractime; tempstmp = pntohl(&reftime[0]); tempfrac = pntohl(&reftime[4]); if ((tempstmp == 0) && (tempfrac == 0)) { strcpy (buff, "NULL"); return buff; } else { temptime = tempstmp - (guint32) NTP_BASETIME; bd = gmtime(&temptime); if (bd != NULL) { fractime = bd->tm_sec + tempfrac / 4294967296.0; snprintf(buff, NTP_TS_SIZE, "%04d-%02d-%02d %02d:%02d:%07.4f UTC", bd->tm_year + 1900, bd->tm_mon + 1, bd->tm_mday, bd->tm_hour, bd->tm_min, fractime); } else strncpy(buff, "Not representable", NTP_TS_SIZE); } return buff; } /* dissect_ntp - dissects NTP packet data * tvb - tvbuff for packet data (IN) * pinfo - packet info * proto_tree - resolved protocol tree */ static void dissect_ntp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_tree *ntp_tree, *flags_tree; proto_item *ti, *tf; guint8 flags; guint8 stratum; guint8 ppoll; gint8 precision; double rootdelay; double rootdispersion; const guint8 *refid; guint32 refid_addr; const guint8 *reftime; const guint8 *org; const guint8 *rec; const guint8 *xmt; gchar buff[NTP_TS_SIZE]; int i; if (check_col(pinfo->cinfo, COL_PROTOCOL)) col_set_str(pinfo->cinfo, COL_PROTOCOL, "NTP"); if (check_col(pinfo->cinfo, COL_INFO)) col_set_str(pinfo->cinfo, COL_INFO, "NTP"); if (tree) { /* Adding NTP item and subtree */ ti = proto_tree_add_item(tree, proto_ntp, tvb, 0, -1, FALSE); ntp_tree = proto_item_add_subtree(ti, ett_ntp); flags = tvb_get_guint8(tvb, 0); tf = proto_tree_add_uint(ntp_tree, hf_ntp_flags, tvb, 0, 1, flags); /* Adding flag subtree and items */ flags_tree = proto_item_add_subtree(tf, ett_ntp_flags); proto_tree_add_uint(flags_tree, hf_ntp_flags_li, tvb, 0, 1, flags); proto_tree_add_uint(flags_tree, hf_ntp_flags_vn, tvb, 0, 1, flags); proto_tree_add_uint(flags_tree, hf_ntp_flags_mode, tvb, 0, 1, flags); /* Stratum, 1byte field represents distance from primary source */ stratum = tvb_get_guint8(tvb, 1); if (stratum == 0) { strcpy (buff, "Peer Clock Stratum: unspecified or unavailable (%u)"); } else if (stratum == 1) { strcpy (buff, "Peer Clock Stratum: primary reference (%u)"); } else if ((stratum >= 2) && (stratum <= 15)) { strcpy (buff, "Peer Clock Stratum: secondary reference (%u)"); } else { strcpy (buff, "Peer Clock Stratum: reserved: %u"); } proto_tree_add_uint_format(ntp_tree, hf_ntp_stratum, tvb, 1, 1, stratum, buff, stratum); /* Poll interval, 1byte field indicating the maximum interval * between successive messages, in seconds to the nearest * power of two. */ ppoll = tvb_get_guint8(tvb, 2); proto_tree_add_uint_format(ntp_tree, hf_ntp_ppoll, tvb, 2, 1, ppoll, (((ppoll >= 4) && (ppoll <= 16)) ? "Peer Polling Interval: %u (%u sec)" : "Peer Polling Interval: invalid (%u)"), ppoll, 1 << ppoll); /* Precision, 1byte field indicating the precision of the * local clock, in seconds to the nearest power of two. */ precision = tvb_get_guint8(tvb, 3); proto_tree_add_uint_format(ntp_tree, hf_ntp_precision, tvb, 3, 1, precision, "Peer Clock Precision: %8.6f sec", pow(2, precision)); /* Root Delay is a 32-bit signed fixed-point number indicating * the total roundtrip delay to the primary reference source, * in seconds with fraction point between bits 15 and 16. */ rootdelay = ((gint16)tvb_get_ntohs(tvb, 4)) + (tvb_get_ntohs(tvb, 6) / 65536.0); proto_tree_add_double_format(ntp_tree, hf_ntp_rootdelay, tvb, 4, 4, rootdelay, "Root Delay: %9.4f sec", rootdelay); /* Root Dispersion, 32-bit unsigned fixed-point number indicating * the nominal error relative to the primary reference source, in * seconds with fraction point between bits 15 and 16. */ rootdispersion = ((gint16)tvb_get_ntohs(tvb, 8)) + (tvb_get_ntohs(tvb, 10) / 65536.0); proto_tree_add_double_format(ntp_tree, hf_ntp_rootdispersion, tvb, 8, 4, rootdispersion, "Clock Dispersion: %9.4f sec", rootdispersion); /* Now, there is a problem with secondary servers. Standards * asks from stratum-2 - stratum-15 servers to set this to the * low order 32 bits of the latest transmit timestamp of the * reference source. * But, all V3 and V4 servers set this to IP adress of their * higher level server. My decision was to resolve this address. */ refid = tvb_get_ptr(tvb, 12, 4); if (stratum <= 1) { snprintf (buff, sizeof buff, "Unindentified reference source '%.4s'", refid); for (i = 0; primary_sources[i].id; i++) { if (memcmp (refid, primary_sources[i].id, 4) == 0) { strcpy (buff, primary_sources[i].data); break; } } } else { buff[sizeof(buff) - 1] = '\0'; tvb_memcpy(tvb, (guint8 *)&refid_addr, 12, 4); strncpy (buff, get_hostname (refid_addr), sizeof(buff)); if (buff[sizeof(buff) - 1] != '\0') strcpy(&buff[sizeof(buff) - 4], "..."); } proto_tree_add_bytes_format(ntp_tree, hf_ntp_refid, tvb, 12, 4, refid, "Reference Clock ID: %s", buff); /* Reference Timestamp: This is the time at which the local clock was * last set or corrected. */ reftime = tvb_get_ptr(tvb, 16, 8); proto_tree_add_bytes_format(ntp_tree, hf_ntp_reftime, tvb, 16, 8, reftime, "Reference Clock Update Time: %s", ntp_fmt_ts(reftime, buff)); /* Originate Timestamp: This is the time at which the request departed * the client for the server. */ org = tvb_get_ptr(tvb, 24, 8); proto_tree_add_bytes_format(ntp_tree, hf_ntp_org, tvb, 24, 8, org, "Originate Time Stamp: %s", ntp_fmt_ts(org, buff)); /* Receive Timestamp: This is the time at which the request arrived at * the server. */ rec = tvb_get_ptr(tvb, 32, 8); proto_tree_add_bytes_format(ntp_tree, hf_ntp_rec, tvb, 32, 8, rec, "Receive Time Stamp: %s", ntp_fmt_ts(rec, buff)); /* Transmit Timestamp: This is the time at which the reply departed the * server for the client. */ xmt = tvb_get_ptr(tvb, 40, 8); proto_tree_add_bytes_format(ntp_tree, hf_ntp_xmt, tvb, 40, 8, xmt, "Transmit Time Stamp: %s", ntp_fmt_ts(xmt, buff)); /* When the NTP authentication scheme is implemented, the * Key Identifier and Message Digest fields contain the * message authentication code (MAC) information defined in * Appendix C of RFC-1305. Will print this as hex code for now. */ if ( tvb_reported_length_remaining(tvb, 48) >= 4 ) proto_tree_add_item(ntp_tree, hf_ntp_keyid, tvb, 48, 4, FALSE); if ( tvb_reported_length_remaining(tvb, 52) > 0 ) proto_tree_add_item(ntp_tree, hf_ntp_mac, tvb, 52, tvb_reported_length_remaining(tvb, 52), FALSE); } } void proto_register_ntp(void) { static hf_register_info hf[] = { { &hf_ntp_flags, { "Flags", "ntp.flags", FT_UINT8, BASE_HEX, NULL, 0, "Flags (Leap/Version/Mode)", HFILL }}, { &hf_ntp_flags_li, { "Leap Indicator", "ntp.flags.li", FT_UINT8, BASE_DEC, VALS(li_types), NTP_LI_MASK, "Leap Indicator", HFILL }}, { &hf_ntp_flags_vn, { "Version number", "ntp.flags.vn", FT_UINT8, BASE_DEC, VALS(ver_nums), NTP_VN_MASK, "Version number", HFILL }}, { &hf_ntp_flags_mode, { "Mode", "ntp.flags.mode", FT_UINT8, BASE_DEC, VALS(mode_types), NTP_MODE_MASK, "Mode", HFILL }}, { &hf_ntp_stratum, { "Peer Clock Stratum", "ntp.stratum", FT_UINT8, BASE_DEC, NULL, 0, "Peer Clock Stratum", HFILL }}, { &hf_ntp_ppoll, { "Peer Polling Interval", "ntp.ppoll", FT_UINT8, BASE_DEC, NULL, 0, "Peer Polling Interval", HFILL }}, { &hf_ntp_precision, { "Peer Clock Precision", "ntp.precision", FT_UINT8, BASE_DEC, NULL, 0, "Peer Clock Precision", HFILL }}, { &hf_ntp_rootdelay, { "Root Delay", "ntp.rootdelay", FT_DOUBLE, BASE_DEC, NULL, 0, "Root Delay", HFILL }}, { &hf_ntp_rootdispersion, { "Clock Dispersion", "ntp.rootdispersion", FT_DOUBLE, BASE_DEC, NULL, 0, "Clock Dispersion", HFILL }}, { &hf_ntp_refid, { "Reference Clock ID", "ntp.refid", FT_BYTES, BASE_NONE, NULL, 0, "Reference Clock ID", HFILL }}, { &hf_ntp_reftime, { "Reference Clock Update Time", "ntp.reftime", FT_BYTES, BASE_NONE, NULL, 0, "Reference Clock Update Time", HFILL }}, { &hf_ntp_org, { "Originate Time Stamp", "ntp.org", FT_BYTES, BASE_NONE, NULL, 0, "Originate Time Stamp", HFILL }}, { &hf_ntp_rec, { "Receive Time Stamp", "ntp.rec", FT_BYTES, BASE_NONE, NULL, 0, "Receive Time Stamp", HFILL }}, { &hf_ntp_xmt, { "Transmit Time Stamp", "ntp.xmt", FT_BYTES, BASE_NONE, NULL, 0, "Transmit Time Stamp", HFILL }}, { &hf_ntp_keyid, { "Key ID", "ntp.keyid", FT_BYTES, BASE_HEX, NULL, 0, "Key ID", HFILL }}, { &hf_ntp_mac, { "Message Authentication Code", "ntp.mac", FT_BYTES, BASE_HEX, NULL, 0, "Message Authentication Code", HFILL }}, }; static gint *ett[] = { &ett_ntp, &ett_ntp_flags, }; proto_ntp = proto_register_protocol("Network Time Protocol", "NTP", "ntp"); proto_register_field_array(proto_ntp, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } void proto_reg_handoff_ntp(void) { dissector_handle_t ntp_handle; ntp_handle = create_dissector_handle(dissect_ntp, proto_ntp); dissector_add("udp.port", UDP_PORT_NTP, ntp_handle); dissector_add("tcp.port", TCP_PORT_NTP, ntp_handle); }