Adding upstream version 2.3.5.upstream/2.3.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 654 insertions, 0 deletions

diff --git a/plugins/check_ntp_time.c b/plugins/check_ntp_time.c
new file mode 100644
index 0000000..46cc604
--- /dev/null
+++ b/plugins/check_ntp_time.c
@@ -0,0 +1,654 @@
+/*****************************************************************************
+* 
+* Monitoring check_ntp_time plugin
+* 
+* License: GPL
+* Copyright (c) 2006 Sean Finney <seanius@seanius.net>
+* Copyright (c) 2006-2008 Monitoring Plugins Development Team
+* 
+* Description:
+* 
+* This file contains the check_ntp_time plugin
+* 
+* This plugin checks the clock offset between the local host and a
+* remote NTP server. It is independent of any commandline programs or
+* external libraries.
+* 
+* If you'd rather want to monitor an NTP server, please use
+* check_ntp_peer.
+* 
+* 
+* 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 3 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, see <http://www.gnu.org/licenses/>.
+* 
+* 
+*****************************************************************************/
+
+const char *progname = "check_ntp_time";
+const char *copyright = "2006-2008";
+const char *email = "devel@monitoring-plugins.org";
+
+#include "common.h"
+#include "netutils.h"
+#include "utils.h"
+
+static char *server_address=NULL;
+static char *port="123";
+static int verbose=0;
+static int quiet=0;
+static char *owarn="60";
+static char *ocrit="120";
+static int time_offset=0;
+
+int process_arguments (int, char **);
+thresholds *offset_thresholds = NULL;
+void print_help (void);
+void print_usage (void);
+
+/* number of times to perform each request to get a good average. */
+#ifndef AVG_NUM
+#define AVG_NUM 4
+#endif
+
+/* max size of control message data */
+#define MAX_CM_SIZE 468
+
+/* this structure holds everything in an ntp request/response as per rfc1305 */
+typedef struct {
+	uint8_t flags;       /* byte with leapindicator,vers,mode. see macros */
+	uint8_t stratum;     /* clock stratum */
+	int8_t poll;         /* polling interval */
+	int8_t precision;    /* precision of the local clock */
+	int32_t rtdelay;     /* total rt delay, as a fixed point num. see macros */
+	uint32_t rtdisp;     /* like above, but for max err to primary src */
+	uint32_t refid;      /* ref clock identifier */
+	uint64_t refts;      /* reference timestamp.  local time local clock */
+	uint64_t origts;     /* time at which request departed client */
+	uint64_t rxts;       /* time at which request arrived at server */
+	uint64_t txts;       /* time at which request departed server */
+} ntp_message;
+
+/* this structure holds data about results from querying offset from a peer */
+typedef struct {
+	time_t waiting;         /* ts set when we started waiting for a response */
+	int num_responses;      /* number of successfully received responses */
+	uint8_t stratum;        /* copied verbatim from the ntp_message */
+	double rtdelay;         /* converted from the ntp_message */
+	double rtdisp;          /* converted from the ntp_message */
+	double offset[AVG_NUM]; /* offsets from each response */
+	uint8_t flags;       /* byte with leapindicator,vers,mode. see macros */
+} ntp_server_results;
+
+/* bits 1,2 are the leap indicator */
+#define LI_MASK 0xc0
+#define LI(x) ((x&LI_MASK)>>6)
+#define LI_SET(x,y) do{ x |= ((y<<6)&LI_MASK); }while(0)
+/* and these are the values of the leap indicator */
+#define LI_NOWARNING 0x00
+#define LI_EXTRASEC 0x01
+#define LI_MISSINGSEC 0x02
+#define LI_ALARM 0x03
+/* bits 3,4,5 are the ntp version */
+#define VN_MASK 0x38
+#define VN(x)	((x&VN_MASK)>>3)
+#define VN_SET(x,y)	do{ x |= ((y<<3)&VN_MASK); }while(0)
+#define VN_RESERVED 0x02
+/* bits 6,7,8 are the ntp mode */
+#define MODE_MASK 0x07
+#define MODE(x) (x&MODE_MASK)
+#define MODE_SET(x,y)	do{ x |= (y&MODE_MASK); }while(0)
+/* here are some values */
+#define MODE_CLIENT 0x03
+#define MODE_CONTROLMSG 0x06
+/* In control message, bits 8-10 are R,E,M bits */
+#define REM_MASK 0xe0
+#define REM_RESP 0x80
+#define REM_ERROR 0x40
+#define REM_MORE 0x20
+/* In control message, bits 11 - 15 are opcode */
+#define OP_MASK 0x1f
+#define OP_SET(x,y)   do{ x |= (y&OP_MASK); }while(0)
+#define OP_READSTAT 0x01
+#define OP_READVAR  0x02
+/* In peer status bytes, bits 6,7,8 determine clock selection status */
+#define PEER_SEL(x) ((ntohs(x)>>8)&0x07)
+#define PEER_INCLUDED 0x04
+#define PEER_SYNCSOURCE 0x06
+
+/**
+ ** a note about the 32-bit "fixed point" numbers:
+ **
+ they are divided into halves, each being a 16-bit int in network byte order:
+ - the first 16 bits are an int on the left side of a decimal point.
+ - the second 16 bits represent a fraction n/(2^16)
+ likewise for the 64-bit "fixed point" numbers with everything doubled :)
+ **/
+
+/* macros to access the left/right 16 bits of a 32-bit ntp "fixed point"
+   number.  note that these can be used as lvalues too */
+#define L16(x) (((uint16_t*)&x)[0])
+#define R16(x) (((uint16_t*)&x)[1])
+/* macros to access the left/right 32 bits of a 64-bit ntp "fixed point"
+   number.  these too can be used as lvalues */
+#define L32(x) (((uint32_t*)&x)[0])
+#define R32(x) (((uint32_t*)&x)[1])
+
+/* ntp wants seconds since 1/1/00, epoch is 1/1/70.  this is the difference */
+#define EPOCHDIFF 0x83aa7e80UL
+
+/* extract a 32-bit ntp fixed point number into a double */
+#define NTP32asDOUBLE(x) (ntohs(L16(x)) + (double)ntohs(R16(x))/65536.0)
+
+/* likewise for a 64-bit ntp fp number */
+#define NTP64asDOUBLE(n) (double)(((uint64_t)n)?\
+                         (ntohl(L32(n))-EPOCHDIFF) + \
+                         (.00000001*(0.5+(double)(ntohl(R32(n))/42.94967296))):\
+                         0)
+
+/* convert a struct timeval to a double */
+#define TVasDOUBLE(x) (double)(x.tv_sec+(0.000001*x.tv_usec))
+
+/* convert an ntp 64-bit fp number to a struct timeval */
+#define NTP64toTV(n,t) \
+	do{ if(!n) t.tv_sec = t.tv_usec = 0; \
+	    else { \
+			t.tv_sec=ntohl(L32(n))-EPOCHDIFF; \
+			t.tv_usec=(int)(0.5+(double)(ntohl(R32(n))/4294.967296)); \
+		} \
+	}while(0)
+
+/* convert a struct timeval to an ntp 64-bit fp number */
+#define TVtoNTP64(t,n) \
+	do{ if(!t.tv_usec && !t.tv_sec) n=0x0UL; \
+		else { \
+			L32(n)=htonl(t.tv_sec + EPOCHDIFF); \
+			R32(n)=htonl((uint64_t)((4294.967296*t.tv_usec)+.5)); \
+		} \
+	} while(0)
+
+/* NTP control message header is 12 bytes, plus any data in the data
+ * field, plus null padding to the nearest 32-bit boundary per rfc.
+ */
+#define SIZEOF_NTPCM(m) (12+ntohs(m.count)+((m.count)?4-(ntohs(m.count)%4):0))
+
+/* finally, a little helper or two for debugging: */
+#define DBG(x) do{if(verbose>1){ x; }}while(0);
+#define PRINTSOCKADDR(x) \
+	do{ \
+		printf("%u.%u.%u.%u", (x>>24)&0xff, (x>>16)&0xff, (x>>8)&0xff, x&0xff);\
+	}while(0);
+
+/* calculate the offset of the local clock */
+static inline double calc_offset(const ntp_message *m, const struct timeval *t){
+	double client_tx, peer_rx, peer_tx, client_rx;
+	client_tx = NTP64asDOUBLE(m->origts);
+	peer_rx = NTP64asDOUBLE(m->rxts);
+	peer_tx = NTP64asDOUBLE(m->txts);
+	client_rx=TVasDOUBLE((*t));
+	return (.5*((peer_tx-client_rx)+(peer_rx-client_tx)));
+}
+
+/* print out a ntp packet in human readable/debuggable format */
+void print_ntp_message(const ntp_message *p){
+	struct timeval ref, orig, rx, tx;
+
+	NTP64toTV(p->refts,ref);
+	NTP64toTV(p->origts,orig);
+	NTP64toTV(p->rxts,rx);
+	NTP64toTV(p->txts,tx);
+
+	printf("packet contents:\n");
+	printf("\tflags: 0x%.2x\n", p->flags);
+	printf("\t  li=%d (0x%.2x)\n", LI(p->flags), p->flags&LI_MASK);
+	printf("\t  vn=%d (0x%.2x)\n", VN(p->flags), p->flags&VN_MASK);
+	printf("\t  mode=%d (0x%.2x)\n", MODE(p->flags), p->flags&MODE_MASK);
+	printf("\tstratum = %d\n", p->stratum);
+	printf("\tpoll = %g\n", pow(2, p->poll));
+	printf("\tprecision = %g\n", pow(2, p->precision));
+	printf("\trtdelay = %-.16g\n", NTP32asDOUBLE(p->rtdelay));
+	printf("\trtdisp = %-.16g\n", NTP32asDOUBLE(p->rtdisp));
+	printf("\trefid = %x\n", p->refid);
+	printf("\trefts = %-.16g\n", NTP64asDOUBLE(p->refts));
+	printf("\torigts = %-.16g\n", NTP64asDOUBLE(p->origts));
+	printf("\trxts = %-.16g\n", NTP64asDOUBLE(p->rxts));
+	printf("\ttxts = %-.16g\n", NTP64asDOUBLE(p->txts));
+}
+
+void setup_request(ntp_message *p){
+	struct timeval t;
+
+	memset(p, 0, sizeof(ntp_message));
+	LI_SET(p->flags, LI_ALARM);
+	VN_SET(p->flags, 4);
+	MODE_SET(p->flags, MODE_CLIENT);
+	p->poll=4;
+	p->precision=(int8_t)0xfa;
+	L16(p->rtdelay)=htons(1);
+	L16(p->rtdisp)=htons(1);
+
+	gettimeofday(&t, NULL);
+	TVtoNTP64(t,p->txts);
+}
+
+/* select the "best" server from a list of servers, and return its index.
+ * this is done by filtering servers based on stratum, dispersion, and
+ * finally round-trip delay. */
+int best_offset_server(const ntp_server_results *slist, int nservers){
+	int cserver=0, best_server=-1;
+
+	/* for each server */
+	for(cserver=0; cserver<nservers; cserver++){
+		/* We don't want any servers that fails these tests */
+		/* Sort out servers that didn't respond or responede with a 0 stratum;
+		 * stratum 0 is for reference clocks so no NTP server should ever report
+		 * a stratum 0 */
+		if ( slist[cserver].stratum == 0){
+			if (verbose) printf("discarding peer %d: stratum=%d\n", cserver, slist[cserver].stratum);
+			continue;
+		}
+		/* Sort out servers with error flags */
+		if ( LI(slist[cserver].flags) == LI_ALARM ){
+			if (verbose) printf("discarding peer %d: flags=%d\n", cserver, LI(slist[cserver].flags));
+			continue;
+		}
+
+		/* If we don't have a server yet, use the first one */
+		if (best_server == -1) {
+			best_server = cserver;
+			DBG(printf("using peer %d as our first candidate\n", best_server));
+			continue;
+		}
+
+		/* compare the server to the best one we've seen so far */
+		/* does it have an equal or better stratum? */
+		DBG(printf("comparing peer %d with peer %d\n", cserver, best_server));
+		if(slist[cserver].stratum <= slist[best_server].stratum){
+			DBG(printf("stratum for peer %d <= peer %d\n", cserver, best_server));
+			/* does it have an equal or better dispersion? */
+			if(slist[cserver].rtdisp <= slist[best_server].rtdisp){
+				DBG(printf("dispersion for peer %d <= peer %d\n", cserver, best_server));
+				/* does it have a better rtdelay? */
+				if(slist[cserver].rtdelay < slist[best_server].rtdelay){
+					DBG(printf("rtdelay for peer %d < peer %d\n", cserver, best_server));
+					best_server = cserver;
+					DBG(printf("peer %d is now our best candidate\n", best_server));
+				}
+			}
+		}
+	}
+
+	if(best_server >= 0) {
+		DBG(printf("best server selected: peer %d\n", best_server));
+		return best_server;
+	} else {
+		DBG(printf("no peers meeting synchronization criteria :(\n"));
+		return -1;
+	}
+}
+
+/* do everything we need to get the total average offset
+ * - we use a certain amount of parallelization with poll() to ensure
+ *   we don't waste time sitting around waiting for single packets.
+ * - we also "manually" handle resolving host names and connecting, because
+ *   we have to do it in a way that our lazy macros don't handle currently :( */
+double offset_request(const char *host, int *status){
+	int i=0, j=0, ga_result=0, num_hosts=0, *socklist=NULL, respnum=0;
+	int servers_completed=0, one_read=0, servers_readable=0, best_index=-1;
+	time_t now_time=0, start_ts=0;
+	ntp_message *req=NULL;
+	double avg_offset=0.;
+	struct timeval recv_time;
+	struct addrinfo *ai=NULL, *ai_tmp=NULL, hints;
+	struct pollfd *ufds=NULL;
+	ntp_server_results *servers=NULL;
+
+	/* setup hints to only return results from getaddrinfo that we'd like */
+	memset(&hints, 0, sizeof(struct addrinfo));
+	hints.ai_family = address_family;
+	hints.ai_protocol = IPPROTO_UDP;
+	hints.ai_socktype = SOCK_DGRAM;
+
+	/* fill in ai with the list of hosts resolved by the host name */
+	ga_result = getaddrinfo(host, port, &hints, &ai);
+	if(ga_result!=0){
+		die(STATE_UNKNOWN, "error getting address for %s: %s\n",
+		    host, gai_strerror(ga_result));
+	}
+
+	/* count the number of returned hosts, and allocate stuff accordingly */
+	for(ai_tmp=ai; ai_tmp!=NULL; ai_tmp=ai_tmp->ai_next){ num_hosts++; }
+	req=(ntp_message*)malloc(sizeof(ntp_message)*num_hosts);
+	if(req==NULL) die(STATE_UNKNOWN, "can not allocate ntp message array");
+	socklist=(int*)malloc(sizeof(int)*num_hosts);
+	if(socklist==NULL) die(STATE_UNKNOWN, "can not allocate socket array");
+	ufds=(struct pollfd*)malloc(sizeof(struct pollfd)*num_hosts);
+	if(ufds==NULL) die(STATE_UNKNOWN, "can not allocate socket array");
+	servers=(ntp_server_results*)malloc(sizeof(ntp_server_results)*num_hosts);
+	if(servers==NULL) die(STATE_UNKNOWN, "can not allocate server array");
+	memset(servers, 0, sizeof(ntp_server_results)*num_hosts);
+	DBG(printf("Found %d peers to check\n", num_hosts));
+
+	/* setup each socket for writing, and the corresponding struct pollfd */
+	ai_tmp=ai;
+	for(i=0;ai_tmp;i++){
+		socklist[i]=socket(ai_tmp->ai_family, SOCK_DGRAM, IPPROTO_UDP);
+		if(socklist[i] == -1) {
+			perror(NULL);
+			die(STATE_UNKNOWN, "can not create new socket");
+		}
+		if(connect(socklist[i], ai_tmp->ai_addr, ai_tmp->ai_addrlen)){
+			/* don't die here, because it is enough if there is one server
+			   answering in time. This also would break for dual ipv4/6 stacked
+			   ntp servers when the client only supports on of them.
+			 */
+			DBG(printf("can't create socket connection on peer %i: %s\n", i, strerror(errno)));
+		} else {
+			ufds[i].fd=socklist[i];
+			ufds[i].events=POLLIN;
+			ufds[i].revents=0;
+		}
+		ai_tmp = ai_tmp->ai_next;
+	}
+
+	/* now do AVG_NUM checks to each host. We stop before timeout/2 seconds
+	 * have passed in order to ensure post-processing and jitter time. */
+	now_time=start_ts=time(NULL);
+	while(servers_completed<num_hosts && now_time-start_ts <= socket_timeout/2){
+		/* loop through each server and find each one which hasn't
+		 * been touched in the past second or so and is still lacking
+		 * some responses. For each of these servers, send a new request,
+		 * and update the "waiting" timestamp with the current time. */
+		now_time=time(NULL);
+
+		for(i=0; i<num_hosts; i++){
+			if(servers[i].waiting<now_time && servers[i].num_responses<AVG_NUM){
+				if(verbose && servers[i].waiting != 0) printf("re-");
+				if(verbose) printf("sending request to peer %d\n", i);
+				setup_request(&req[i]);
+				write(socklist[i], &req[i], sizeof(ntp_message));
+				servers[i].waiting=now_time;
+				break;
+			}
+		}
+
+		/* quickly poll for any sockets with pending data */
+		servers_readable=poll(ufds, num_hosts, 100);
+		if(servers_readable==-1){
+			perror("polling ntp sockets");
+			die(STATE_UNKNOWN, "communication errors");
+		}
+
+		/* read from any sockets with pending data */
+		for(i=0; servers_readable && i<num_hosts; i++){
+			if(ufds[i].revents&POLLIN && servers[i].num_responses < AVG_NUM){
+				if(verbose) {
+					printf("response from peer %d: ", i);
+				}
+
+				read(ufds[i].fd, &req[i], sizeof(ntp_message));
+				gettimeofday(&recv_time, NULL);
+				DBG(print_ntp_message(&req[i]));
+				respnum=servers[i].num_responses++;
+				servers[i].offset[respnum]=calc_offset(&req[i], &recv_time)+time_offset;
+				if(verbose) {
+					printf("offset %.10g\n", servers[i].offset[respnum]);
+				}
+				servers[i].stratum=req[i].stratum;
+				servers[i].rtdisp=NTP32asDOUBLE(req[i].rtdisp);
+				servers[i].rtdelay=NTP32asDOUBLE(req[i].rtdelay);
+				servers[i].waiting=0;
+				servers[i].flags=req[i].flags;
+				servers_readable--;
+				one_read = 1;
+				if(servers[i].num_responses==AVG_NUM) servers_completed++;
+			}
+		}
+		/* lather, rinse, repeat. */
+	}
+
+	if (one_read == 0) {
+		die(STATE_CRITICAL, "NTP CRITICAL: No response from NTP server\n");
+	}
+
+	/* now, pick the best server from the list */
+	best_index=best_offset_server(servers, num_hosts);
+	if(best_index < 0){
+		*status=STATE_UNKNOWN;
+	} else {
+		/* finally, calculate the average offset */
+		for(i=0; i<servers[best_index].num_responses;i++){
+			avg_offset+=servers[best_index].offset[i];
+		}
+		avg_offset/=servers[best_index].num_responses;
+	}
+
+	/* cleanup */
+	for(j=0; j<num_hosts; j++){ close(socklist[j]); }
+	free(socklist);
+	free(ufds);
+	free(servers);
+	free(req);
+	freeaddrinfo(ai);
+
+	if(verbose) printf("overall average offset: %.10g\n", avg_offset);
+	return avg_offset;
+}
+
+int process_arguments(int argc, char **argv){
+	int c;
+	int option=0;
+	static struct option longopts[] = {
+		{"version", no_argument, 0, 'V'},
+		{"help", no_argument, 0, 'h'},
+		{"verbose", no_argument, 0, 'v'},
+		{"use-ipv4", no_argument, 0, '4'},
+		{"use-ipv6", no_argument, 0, '6'},
+		{"quiet", no_argument, 0, 'q'},
+		{"time-offset", optional_argument, 0, 'o'},
+		{"warning", required_argument, 0, 'w'},
+		{"critical", required_argument, 0, 'c'},
+		{"timeout", required_argument, 0, 't'},
+		{"hostname", required_argument, 0, 'H'},
+		{"port", required_argument, 0, 'p'},
+		{0, 0, 0, 0}
+	};
+
+
+	if (argc < 2)
+		usage ("\n");
+
+	while (1) {
+		c = getopt_long (argc, argv, "Vhv46qw:c:t:H:p:o:", longopts, &option);
+		if (c == -1 || c == EOF || c == 1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_help();
+			exit(STATE_UNKNOWN);
+			break;
+		case 'V':
+			print_revision(progname, NP_VERSION);
+			exit(STATE_UNKNOWN);
+			break;
+		case 'v':
+			verbose++;
+			break;
+		case 'q':
+			quiet = 1;
+			break;
+		case 'w':
+			owarn = optarg;
+			break;
+		case 'c':
+			ocrit = optarg;
+			break;
+		case 'H':
+			if(is_host(optarg) == FALSE)
+				usage2(_("Invalid hostname/address"), optarg);
+			server_address = strdup(optarg);
+			break;
+		case 'p':
+			port = strdup(optarg);
+			break;
+		case 't':
+			socket_timeout=atoi(optarg);
+			break;
+		case 'o':
+			time_offset=atoi(optarg);
+                        break;
+		case '4':
+			address_family = AF_INET;
+			break;
+		case '6':
+#ifdef USE_IPV6
+			address_family = AF_INET6;
+#else
+			usage4 (_("IPv6 support not available"));
+#endif
+			break;
+		case '?':
+			/* print short usage statement if args not parsable */
+			usage5 ();
+			break;
+		}
+	}
+
+	if(server_address == NULL){
+		usage4(_("Hostname was not supplied"));
+	}
+
+	return 0;
+}
+
+char *perfd_offset (double offset)
+{
+	return fperfdata ("offset", offset, "s",
+		TRUE, offset_thresholds->warning->end,
+		TRUE, offset_thresholds->critical->end,
+		FALSE, 0, FALSE, 0);
+}
+
+int main(int argc, char *argv[]){
+	int result, offset_result;
+	double offset=0;
+	char *result_line, *perfdata_line;
+
+	setlocale (LC_ALL, "");
+	bindtextdomain (PACKAGE, LOCALEDIR);
+	textdomain (PACKAGE);
+
+	result = offset_result = STATE_OK;
+
+	/* Parse extra opts if any */
+	argv=np_extra_opts (&argc, argv, progname);
+
+	if (process_arguments (argc, argv) == ERROR)
+		usage4 (_("Could not parse arguments"));
+
+	set_thresholds(&offset_thresholds, owarn, ocrit);
+
+	/* initialize alarm signal handling */
+	signal (SIGALRM, socket_timeout_alarm_handler);
+
+	/* set socket timeout */
+	alarm (socket_timeout);
+
+	offset = offset_request(server_address, &offset_result);
+	if (offset_result == STATE_UNKNOWN) {
+		result = (quiet == 1 ? STATE_UNKNOWN : STATE_CRITICAL);
+	} else {
+		result = get_status(fabs(offset), offset_thresholds);
+	}
+
+	switch (result) {
+		case STATE_CRITICAL :
+			xasprintf(&result_line, _("NTP CRITICAL:"));
+			break;
+		case STATE_WARNING :
+			xasprintf(&result_line, _("NTP WARNING:"));
+			break;
+		case STATE_OK :
+			xasprintf(&result_line, _("NTP OK:"));
+			break;
+		default :
+			xasprintf(&result_line, _("NTP UNKNOWN:"));
+			break;
+	}
+	if(offset_result == STATE_UNKNOWN){
+		xasprintf(&result_line, "%s %s", result_line, _("Offset unknown"));
+		xasprintf(&perfdata_line, "");
+	} else {
+		xasprintf(&result_line, "%s %s %.10g secs", result_line, _("Offset"), offset);
+		xasprintf(&perfdata_line, "%s", perfd_offset(offset));
+	}
+	printf("%s|%s\n", result_line, perfdata_line);
+
+	if(server_address!=NULL) free(server_address);
+	return result;
+}
+
+void print_help(void){
+	print_revision(progname, NP_VERSION);
+
+	printf ("Copyright (c) 2006 Sean Finney\n");
+	printf (COPYRIGHT, copyright, email);
+
+	printf ("%s\n", _("This plugin checks the clock offset with the ntp server"));
+
+	printf ("\n\n");
+
+	print_usage();
+	printf (UT_HELP_VRSN);
+	printf (UT_EXTRA_OPTS);
+	printf (UT_IPv46);
+	printf (UT_HOST_PORT, 'p', "123");
+	printf (" %s\n", "-q, --quiet");
+	printf ("    %s\n", _("Returns UNKNOWN instead of CRITICAL if offset cannot be found"));
+	printf (" %s\n", "-w, --warning=THRESHOLD");
+	printf ("    %s\n", _("Offset to result in warning status (seconds)"));
+	printf (" %s\n", "-c, --critical=THRESHOLD");
+	printf ("    %s\n", _("Offset to result in critical status (seconds)"));
+	printf (" %s\n", "-o, --time_offset=INTEGER");
+	printf ("    %s\n", _("Expected offset of the ntp server relative to local server (seconds)"));
+	printf (UT_CONN_TIMEOUT, DEFAULT_SOCKET_TIMEOUT);
+	printf (UT_VERBOSE);
+
+	printf("\n");
+	printf("%s\n", _("This plugin checks the clock offset between the local host and a"));
+	printf("%s\n", _("remote NTP server. It is independent of any commandline programs or"));
+	printf("%s\n", _("external libraries."));
+
+	printf("\n");
+	printf("%s\n", _("Notes:"));
+	printf(" %s\n", _("If you'd rather want to monitor an NTP server, please use"));
+	printf(" %s\n", _("check_ntp_peer."));
+	printf(" %s\n", _("--time-offset is useful for compensating for servers with known"));
+	printf(" %s\n", _("and expected clock skew."));
+	printf("\n");
+	printf(UT_THRESHOLDS_NOTES);
+
+	printf("\n");
+	printf("%s\n", _("Examples:"));
+	printf("  %s\n", ("./check_ntp_time -H ntpserv -w 0.5 -c 1"));
+
+	printf (UT_SUPPORT);
+}
+
+void
+print_usage(void)
+{
+	printf ("%s\n", _("Usage:"));
+	printf(" %s -H <host> [-4|-6] [-w <warn>] [-c <crit>] [-v verbose] [-o <time offset>]\n", progname);
+}
+