1.Dd January 20 2016 2.Dt SNTP 1sntpmdoc User Commands 3.Os 4.\" EDIT THIS FILE WITH CAUTION (sntp-opts.mdoc) 5.\" 6.\" It has been AutoGen-ed January 20, 2016 at 04:06:45 AM by AutoGen 5.18.5 7.\" From the definitions sntp-opts.def 8.\" and the template file agmdoc-cmd.tpl 9.Sh NAME 10.Nm sntp 11.Nd standard Simple Network Time Protocol client program 12.Sh SYNOPSIS 13.Nm 14.\" Mixture of short (flag) options and long options 15.Op Fl flags 16.Op Fl flag Op Ar value 17.Op Fl \-option\-name Ns Oo Oo Ns "=| " Oc Ns Ar value Oc 18[ hostname\-or\-IP ...] 19.Pp 20.Sh DESCRIPTION 21.Nm 22can be used as an SNTP client to query a NTP or SNTP server and either display 23the time or set the local system's time (given suitable privilege). It can be 24run as an interactive command or from a 25.Ic cron 26job. 27NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol) 28are defined and described by RFC 5905. 29.Pp 30The default is to write the estimated correct local date and time (i.e. not 31UTC) to the standard output in a format like: 32.Ic "'1996\-10\-15 20:17:25.123 (+0800) +4.567 +/\- 0.089 [host] IP sN'" 33where the 34.Ic "'(+0800)'" 35means that to get to UTC from the reported local time one must 36add 8 hours and 0 minutes, 37the 38.Ic "'+4.567'" 39indicates the local clock is 4.567 seconds behind the correct time 40(so 4.567 seconds must be added to the local clock to get it to be correct). 41Note that the number of decimals printed for this value will change 42based on the reported precision of the server. 43.Ic "'+/\- 0.089'" 44is the reported 45.Em synchronization distance 46(in seconds), which represents the maximum error due to all causes. 47If the server does not report valid data needed to calculate the 48synchronization distance, this will be reported as 49.Ic "'+/\- ?'" . 50If the 51.Em host 52is different from the 53.Em IP , 54both will be displayed. 55Otherwise, only the 56.Em IP 57is displayed. 58Finally, the 59.Em stratum 60of the host is reported 61and the leap indicator is decoded and displayed. 62.Sh "OPTIONS" 63.Bl -tag 64.It Fl 4 , Fl \-ipv4 65Force IPv4 DNS name resolution. 66This option must not appear in combination with any of the following options: 67ipv6. 68.sp 69Force DNS resolution of the following host names on the command line 70to the IPv4 namespace. 71.It Fl 6 , Fl \-ipv6 72Force IPv6 DNS name resolution. 73This option must not appear in combination with any of the following options: 74ipv4. 75.sp 76Force DNS resolution of the following host names on the command line 77to the IPv6 namespace. 78.It Fl a Ar auth\-keynumber , Fl \-authentication Ns = Ns Ar auth\-keynumber 79Enable authentication with the key \fBauth\-keynumber\fP. 80This option takes an integer number as its argument. 81.sp 82Enable authentication using the key specified in this option's 83argument. The argument of this option is the \fBkeyid\fP, a 84number specified in the \fBkeyfile\fP as this key's identifier. 85See the \fBkeyfile\fP option (\fB\-k\fP) for more details. 86.It Fl b Ar broadcast\-address , Fl \-broadcast Ns = Ns Ar broadcast\-address 87Listen to the address specified for broadcast time sync. 88This option may appear an unlimited number of times. 89.sp 90If specified \fBsntp\fP will listen to the specified address 91for NTP broadcasts. The default maximum wait time 92can (and probably should) be modified with \fB\-t\fP. 93.It Fl c Ar host\-name , Fl \-concurrent Ns = Ns Ar host\-name 94Concurrently query all IPs returned for host\-name. 95This option may appear an unlimited number of times. 96.sp 97Requests from an NTP "client" to a "server" should never be sent 98more rapidly than one every 2 seconds. By default, any IPs returned 99as part of a DNS lookup are assumed to be for a single instance of 100\fBntpd\fP, and therefore \fBsntp\fP will send queries to these IPs 101one after another, with a 2\-second gap in between each query. 102.sp 103The \fB\-c\fP or \fB\-\-concurrent\fP flag says that any IPs 104returned for the DNS lookup of the supplied host\-name are on 105different machines, so we can send concurrent queries. 106.It Fl d , Fl \-debug\-level 107Increase debug verbosity level. 108This option may appear an unlimited number of times. 109.sp 110.It Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number 111Set the debug verbosity level. 112This option may appear an unlimited number of times. 113This option takes an integer number as its argument. 114.sp 115.It Fl g Ar milliseconds , Fl \-gap Ns = Ns Ar milliseconds 116The gap (in milliseconds) between time requests. 117This option takes an integer number as its argument. 118The default 119.Ar milliseconds 120for this option is: 121.ti +4 122 50 123.sp 124Since we're only going to use the first valid response we get and 125there is benefit to specifying a good number of servers to query, 126separate the queries we send out by the specified number of 127milliseconds. 128.It Fl K Ar file\-name , Fl \-kod Ns = Ns Ar file\-name 129KoD history filename. 130The default 131.Ar file\-name 132for this option is: 133.ti +4 134 /var/db/ntp\-kod 135.sp 136Specifies the filename to be used for the persistent history of KoD 137responses received from servers. If the file does not exist, a 138warning message will be displayed. The file will not be created. 139.It Fl k Ar file\-name , Fl \-keyfile Ns = Ns Ar file\-name 140Look in this file for the key specified with \fB\-a\fP. 141.sp 142This option specifies the keyfile. 143\fBsntp\fP will search for the key specified with \fB\-a\fP 144\fIkeyno\fP in this file. See \fBntp.keys(5)\fP for more 145information. 146.It Fl l Ar file\-name , Fl \-logfile Ns = Ns Ar file\-name 147Log to specified logfile. 148.sp 149This option causes the client to write log messages to the specified 150\fIlogfile\fP. 151.It Fl M Ar number , Fl \-steplimit Ns = Ns Ar number 152Adjustments less than \fBsteplimit\fP msec will be slewed. 153This option takes an integer number as its argument. 154The value of 155.Ar number 156is constrained to being: 157.in +4 158.nf 159.na 160greater than or equal to 0 161.fi 162.in -4 163.sp 164If the time adjustment is less than \fIsteplimit\fP milliseconds, 165slew the amount using \fBadjtime(2)\fP. Otherwise, step the 166correction using \fBsettimeofday(2)\fP. The default value is 0, 167which means all adjustments will be stepped. This is a feature, as 168different situations demand different values. 169.It Fl o Ar number , Fl \-ntpversion Ns = Ns Ar number 170Send \fBint\fP as our NTP protocol version. 171This option takes an integer number as its argument. 172The value of 173.Ar number 174is constrained to being: 175.in +4 176.nf 177.na 178in the range 0 through 7 179.fi 180.in -4 181The default 182.Ar number 183for this option is: 184.ti +4 185 4 186.sp 187When sending requests to a remote server, tell them we are running 188NTP protocol version \fIntpversion\fP . 189.It Fl r , Fl \-usereservedport 190Use the NTP Reserved Port (port 123). 191.sp 192Use port 123, which is reserved for NTP, for our network 193communications. 194.It Fl S , Fl \-step 195OK to 'step' the time with \fBsettimeofday(2)\fP. 196.sp 197.It Fl s , Fl \-slew 198OK to 'slew' the time with \fBadjtime(2)\fP. 199.sp 200.It Fl t Ar seconds , Fl \-timeout Ns = Ns Ar seconds 201The number of seconds to wait for responses. 202This option takes an integer number as its argument. 203The default 204.Ar seconds 205for this option is: 206.ti +4 207 5 208.sp 209When waiting for a reply, \fBsntp\fP will wait the number 210of seconds specified before giving up. The default should be 211more than enough for a unicast response. If \fBsntp\fP is 212only waiting for a broadcast response a longer timeout is 213likely needed. 214.It Fl \-wait , " Fl \-no\-wait" 215Wait for pending replies (if not setting the time). 216The \fIno\-wait\fP form will disable the option. 217This option is enabled by default. 218.sp 219If we are not setting the time, wait for all pending responses. 220.It Fl \&? , Fl \-help 221Display usage information and exit. 222.It Fl \&! , Fl \-more\-help 223Pass the extended usage information through a pager. 224.It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc 225Save the option state to \fIcfgfile\fP. The default is the \fIlast\fP 226configuration file listed in the \fBOPTION PRESETS\fP section, below. 227The command will exit after updating the config file. 228.It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts 229Load options from \fIcfgfile\fP. 230The \fIno\-load\-opts\fP form will disable the loading 231of earlier config/rc/ini files. \fI\-\-no\-load\-opts\fP is handled early, 232out of order. 233.It Fl \-version Op Brq Ar v|c|n 234Output version of program and exit. The default mode is `v', a simple 235version. The `c' mode will print copyright information and `n' will 236print the full copyright notice. 237.El 238.Sh "OPTION PRESETS" 239Any option that is not marked as \fInot presettable\fP may be preset 240by loading values from configuration ("RC" or ".INI") file(s) and values from 241environment variables named: 242.nf 243 \fBSNTP_<option\-name>\fP or \fBSNTP\fP 244.fi 245.ad 246The environmental presets take precedence (are processed later than) 247the configuration files. 248The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP". 249If any of these are directories, then the file \fI.ntprc\fP 250is searched for within those directories. 251.Sh USAGE 252.Bl -tag -width indent 253.It Li "sntp ntpserver.somewhere" 254is the simplest use of this program 255and can be run as an unprivileged command 256to check the current time and error in the local clock. 257.It Li "sntp \-Ss \-M 128 ntpserver.somewhere" 258With suitable privilege, 259run as a command 260or from a 261.Xr cron 8 262job, 263.Ic "sntp \-Ss \-M 128 ntpserver.somewhere" 264will request the time from the server, 265and if that server reports that it is synchronized 266then if the offset adjustment is less than 128 milliseconds 267the correction will be slewed, 268and if the correction is more than 128 milliseconds 269the correction will be stepped. 270.It Li "sntp \-S ntpserver.somewhere" 271With suitable privilege, 272run as a command 273or from a 274.Xr cron 8 275job, 276.Ic "sntp \-S ntpserver.somewhere" 277will set (step) the local clock from a synchronized specified server, 278like the (deprecated) 279.Xr ntpdate 1ntpdatemdoc , 280or 281.Xr rdate 8 282commands. 283.El 284.Sh "ENVIRONMENT" 285See \fBOPTION PRESETS\fP for configuration environment variables. 286.Sh "FILES" 287See \fBOPTION PRESETS\fP for configuration files. 288.Sh "EXIT STATUS" 289One of the following exit values will be returned: 290.Bl -tag 291.It 0 " (EXIT_SUCCESS)" 292Successful program execution. 293.It 1 " (EXIT_FAILURE)" 294The operation failed or the command syntax was not valid. 295.It 66 " (EX_NOINPUT)" 296A specified configuration file could not be loaded. 297.It 70 " (EX_SOFTWARE)" 298libopts had an internal operational error. Please report 299it to autogen\-users@lists.sourceforge.net. Thank you. 300.El 301.Sh AUTHORS 302.An "Johannes Maximilian Kuehn" 303.An "Harlan Stenn" 304.An "Dave Hart" 305.Sh "COPYRIGHT" 306Copyright (C) 1992\-2016 The University of Delaware and Network Time Foundation all rights reserved. 307This program is released under the terms of the NTP license, <http://ntp.org/license>. 308.Sh "BUGS" 309Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org 310.Sh "NOTES" 311This manual page was \fIAutoGen\fP\-erated from the \fBsntp\fP 312option definitions. 313