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diff --git a/doc/chronyc.man.in b/doc/chronyc.man.in new file mode 100644 index 0000000..1a6ec02 --- /dev/null +++ b/doc/chronyc.man.in @@ -0,0 +1,1914 @@ +'\" t +.\" Title: chronyc +.\" Author: [see the "AUTHORS" section] +.\" Generator: Asciidoctor 1.5.6.1 +.\" Date: 2018-09-19 +.\" Manual: User manual +.\" Source: chrony @CHRONY_VERSION@ +.\" Language: English +.\" +.TH "CHRONYC" "1" "2018-09-19" "chrony @CHRONY_VERSION@" "User manual" +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.ss \n[.ss] 0 +.nh +.ad l +.de URL +\\$2 \(laURL: \\$1 \(ra\\$3 +.. +.if \n[.g] .mso www.tmac +.LINKSTYLE blue R < > +.SH "NAME" +chronyc \- command\-line interface for chrony daemon +.SH "SYNOPSIS" +.sp +\fBchronyc\fP [\fIOPTION\fP]... [\fICOMMAND\fP]... +.SH "DESCRIPTION" +.sp +\fBchronyc\fP is a command\-line interface program which can be used to monitor +\fBchronyd\fP\(cqs performance and to change various operating parameters whilst it is +running. +.sp +If no commands are specified on the command line, \fBchronyc\fP will expect input +from the user. The prompt \fIchronyc>\fP will be displayed when it is being run +from a terminal. If \fBchronyc\fP\(cqs input or output are redirected from or to a file, +the prompt is not shown. +.sp +There are two ways \fBchronyc\fP can access \fBchronyd\fP. One is the Internet +Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is +accessible locally by the root or \fIchrony\fP user. By default, \fBchronyc\fP first +tries to connect to the Unix domain socket. The compiled\-in default path is +\fI@CHRONYRUNDIR@/chronyd.sock\fP. If that fails (e.g. because \fBchronyc\fP is +running under a non\-root user), it will try to connect to 127.0.0.1 and then +::1. +.sp +Only the following monitoring commands, which do not affect the behaviour of +\fBchronyd\fP, are allowed from the network: \fBactivity\fP, \fBmanual list\fP, +\fBrtcdata\fP, \fBsmoothing\fP, \fBsources\fP, \fBsourcestats\fP, \fBtracking\fP, \fBwaitsync\fP. The +set of hosts from which \fBchronyd\fP will accept these commands can be configured +with the \fBcmdallow\fP directive in the \fBchronyd\fP\(cqs +configuration file or the \fBcmdallow\fP command in \fBchronyc\fP. By +default, the commands are accepted only from localhost (127.0.0.1 or ::1). +.sp +All other commands are allowed only through the Unix domain socket. When sent +over the network, \fBchronyd\fP will respond with a \(oqNot authorised\(cq error, even +if it is from localhost. In chrony versions before 2.2 they were allowed +from the network if they were authenticated with a password, but that is no +longer supported. +.sp +Having full access to \fBchronyd\fP via \fBchronyc\fP is more or less equivalent to +being able to modify the \fBchronyd\fP\(cqs configuration file and restart it. +.SH "OPTIONS" +.sp +\fB\-4\fP +.RS 4 +With this option hostnames will be resolved only to IPv4 addresses. +.RE +.sp +\fB\-6\fP +.RS 4 +With this option hostnames will be resolved only to IPv6 addresses. +.RE +.sp +\fB\-n\fP +.RS 4 +This option disables resolving of IP addresses to hostnames, e.g. to avoid slow +DNS lookups. Long addresses will not be truncated to fit into the column. +.RE +.sp +\fB\-c\fP +.RS 4 +This option enables printing of reports in a comma\-separated values (CSV) +format. IP addresses will not be resolved to hostnames, time will be printed as +number of seconds since the epoch and values in seconds will not be converted +to other units. +.RE +.sp +\fB\-d\fP +.RS 4 +This option enables printing of debugging messages if \fBchronyc\fP was compiled +with debugging support. +.RE +.sp +\fB\-m\fP +.RS 4 +Normally, all arguments on the command line are interpreted as one command. +With this option multiple commands can be specified. Each argument will be +interpreted as a whole command. +.RE +.sp +\fB\-h\fP \fIhost\fP +.RS 4 +This option allows the user to specify which host (or comma\-separated list of +addresses) running the \fBchronyd\fP program is to be contacted. This allows for +remote monitoring, without having to connect over SSH to the other host first. +.sp +The default is to contact \fBchronyd\fP running on the same host where +\fBchronyc\fP is being run. +.RE +.sp +\fB\-p\fP \fIport\fP +.RS 4 +This option allows the user to specify the UDP port number which the target +\fBchronyd\fP is using for its monitoring connections. This defaults to 323; there +would rarely be a need to change this. +.RE +.sp +\fB\-f\fP \fIfile\fP +.RS 4 +This option is ignored and is provided only for compatibility. +.RE +.sp +\fB\-a\fP +.RS 4 +This option is ignored and is provided only for compatibility. +.RE +.sp +\fB\-v\fP +.RS 4 +With this option \fBchronyc\fP displays its version number on the terminal and +exits. +.RE +.SH "COMMANDS" +.sp +This section describes each of the commands available within the \fBchronyc\fP +program. +.SS "System clock" +.sp +\fBtracking\fP +.RS 4 +The \fBtracking\fP command displays parameters about the system\(cqs clock +performance. An example of the output is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +Reference ID : CB00710F (foo.example.net) +Stratum : 3 +Ref time (UTC) : Fri Jan 27 09:49:17 2017 +System time : 0.000006523 seconds slow of NTP time +Last offset : \-0.000006747 seconds +RMS offset : 0.000035822 seconds +Frequency : 3.225 ppm slow +Residual freq : \-0.000 ppm +Skew : 0.129 ppm +Root delay : 0.013639022 seconds +Root dispersion : 0.001100737 seconds +Update interval : 64.2 seconds +Leap status : Normal +.fi +.if n \{\ +.RE +.\} +.sp +The fields are explained as follows: +.sp +\fBReference ID\fP +.RS 4 +This is the reference ID and name (or IP address) of the server to which the +computer is currently synchronised. For IPv4 addresses, the reference ID is +equal to the address and for IPv6 addresses it is the first 32 bits of the MD5 +sum of the address. +.sp +If the reference ID is \fI7F7F0101\fP and there is no name or IP address, it means +the computer is not synchronised to any external source and that you have the +\fIlocal\fP mode operating (via the \fBlocal\fP command in \fBchronyc\fP, or the +\fBlocal\fP directive in the configuration file). +.sp +The reference ID is printed as a hexadecimal number. Note that in older +versions it used to be printed in quad\-dotted notation and could be confused +with an IPv4 address. +.RE +.sp +\fBStratum\fP +.RS 4 +The stratum indicates how many hops away from a computer with an attached +reference clock we are. Such a computer is a stratum\-1 computer, so the +computer in the example is two hops away (i.e. \fIfoo.example.net\fP is a +stratum\-2 and is synchronised from a stratum\-1). +.RE +.sp +\fBRef time\fP +.RS 4 +This is the time (UTC) at which the last measurement from the reference +source was processed. +.RE +.sp +\fBSystem time\fP +.RS 4 +In normal operation, \fBchronyd\fP by default never steps the system clock, because +any jump in the time can have adverse consequences for certain application +programs. Instead, any error in the system clock is corrected by slightly +speeding up or slowing down the system clock until the error has been removed, +and then returning to the system clock\(cqs normal speed. A consequence of this is +that there will be a period when the system clock (as read by other programs) +will be different from \fBchronyd\fP\(cqs estimate of the current true time (which it +reports to NTP clients when it is operating in server mode). The value reported +on this line is the difference due to this effect. +.RE +.sp +\fBLast offset\fP +.RS 4 +This is the estimated local offset on the last clock update. +.RE +.sp +\fBRMS offset\fP +.RS 4 +This is a long\-term average of the offset value. +.RE +.sp +\fBFrequency\fP +.RS 4 +The \(oqfrequency\(cq is the rate by which the system\(cqs clock would be wrong if +\fBchronyd\fP was not correcting it. It is expressed in ppm (parts per million). +For example, a value of 1 ppm would mean that when the system\(cqs clock thinks it +has advanced 1 second, it has actually advanced by 1.000001 seconds relative to +true time. +.RE +.sp +\fBResidual freq\fP +.RS 4 +This shows the \(oqresidual frequency\(cq for the currently selected reference +source. This reflects any difference between what the measurements from the +reference source indicate the frequency should be and the frequency currently +being used. +.sp +The reason this is not always zero is that a smoothing procedure is +applied to the frequency. Each time a measurement from the reference +source is obtained and a new residual frequency computed, the estimated +accuracy of this residual is compared with the estimated accuracy (see +\(oqskew\(cq next) of the existing frequency value. A weighted average is +computed for the new frequency, with weights depending on these accuracies. +If the measurements from the reference source follow a consistent trend, the +residual will be driven to zero over time. +.RE +.sp +\fBSkew\fP +.RS 4 +This is the estimated error bound on the frequency. +.RE +.sp +\fBRoot delay\fP +.RS 4 +This is the total of the network path delays to the stratum\-1 computer from +which the computer is ultimately synchronised. +.RE +.sp +\fBRoot dispersion\fP +.RS 4 +This is the total dispersion accumulated through all the computers back to +the stratum\-1 computer from which the computer is ultimately synchronised. +Dispersion is due to system clock resolution, statistical measurement +variations, etc. +.sp +An absolute bound on the computer\(cqs clock accuracy (assuming the stratum\-1 +computer is correct) is given by: +.sp +.if n \{\ +.RS 4 +.\} +.nf +clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay) +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBUpdate interval\fP +.RS 4 +This is the interval between the last two clock updates. +.RE +.sp +\fBLeap status\fP +.RS 4 +This is the leap status, which can be \fINormal\fP, \fIInsert second\fP, \fIDelete +second\fP or \fINot synchronised\fP. +.RE +.RE +.sp +\fBmakestep\fP, \fBmakestep\fP \fIthreshold\fP \fIlimit\fP +.RS 4 +Normally \fBchronyd\fP will cause the system to gradually correct any time offset, +by slowing down or speeding up the clock as required. In certain situations, +the system clock might be so far adrift that this slewing process would take a +very long time to correct the system clock. +.sp +The \fBmakestep\fP command can be used in this situation. There are two forms of +the command. The first form has no parameters. It tells \fBchronyd\fP to cancel any +remaining correction that was being slewed and jump the system clock by the +equivalent amount, making it correct immediately. +.sp +The second form configures the automatic stepping, similarly to the +\fBmakestep\fP directive. It has two parameters, +stepping threshold (in seconds) and number of future clock updates for which +the threshold will be active. This can be used with the \fBburst\fP +command to quickly make a new measurement and correct the clock by stepping if +needed, without waiting for \fBchronyd\fP to complete the measurement and update +the clock. +.sp +.if n \{\ +.RS 4 +.\} +.nf +makestep 0.1 1 +burst 1/2 +.fi +.if n \{\ +.RE +.\} +.sp +BE WARNED: Certain software will be seriously affected by such jumps in the +system time. (That is the reason why \fBchronyd\fP uses slewing normally.) +.RE +.sp +\fBmaxupdateskew\fP \fIskew\-in\-ppm\fP +.RS 4 +This command has the same effect as the +\fBmaxupdateskew\fP directive in the +configuration file. +.RE +.sp +\fBwaitsync\fP [\fImax\-tries\fP [\fImax\-correction\fP [\fImax\-skew\fP [\fIinterval\fP]]]] +.RS 4 +The \fBwaitsync\fP command waits for \fBchronyd\fP to synchronise. +.sp +Up to four optional arguments can be specified. The first is the maximum number +of tries before giving up and returning a non\-zero error code. When 0 is +specified, or there are no arguments, the number of tries will not be limited. +.sp +The second and third arguments are the maximum allowed remaining correction of +the system clock and the maximum allowed skew (in ppm) as reported by the +\fBtracking\fP command in the \fBSystem time\fP and \fBSkew\fP fields. If not +specified or zero, the value will not be checked. +.sp +The fourth argument is the interval specified in seconds in which the check is +repeated. The interval is 10 seconds by default. +.sp +An example is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +waitsync 60 0.01 +.fi +.if n \{\ +.RE +.\} +.sp +which will wait up to about 10 minutes (60 times 10 seconds) for \fBchronyd\fP to +synchronise to a source and the remaining correction to be less than 10 +milliseconds. +.RE +.SS "Time sources" +.sp +\fBsources\fP [\fB\-v\fP] +.RS 4 +This command displays information about the current time sources that \fBchronyd\fP +is accessing. +.sp +The optional argument \fB\-v\fP can be specified, meaning \fIverbose\fP. In this case, +extra caption lines are shown as a reminder of the meanings of the columns. +.sp +.if n \{\ +.RS 4 +.\} +.nf +210 Number of sources = 3 +MS Name/IP address Stratum Poll Reach LastRx Last sample +=============================================================================== +#* GPS0 0 4 377 11 \-479ns[ \-621ns] +/\- 134ns +^? foo.example.net 2 6 377 23 \-923us[ \-924us] +/\- 43ms +^+ bar.example.net 1 6 377 21 \-2629us[\-2619us] +/\- 86ms +.fi +.if n \{\ +.RE +.\} +.sp +The columns are as follows: +.sp +\fBM\fP +.RS 4 +This indicates the mode of the source. \fI^\fP means a server, \fI=\fP means a peer +and \fI#\fP indicates a locally connected reference clock. +.RE +.sp +\fBS\fP +.RS 4 +This column indicates the state of the source. +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fI*\fP indicates the source to which \fBchronyd\fP is currently synchronised. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fI+\fP indicates acceptable sources which are combined with the selected +source. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fI\-\fP indicates acceptable sources which are excluded by the combining +algorithm. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fI?\fP indicates sources to which connectivity has been lost or whose packets +do not pass all tests. It is also shown at start\-up, until at least 3 samples +have been gathered from it. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fIx\fP indicates a clock which \fBchronyd\fP thinks is a falseticker (i.e. its +time is inconsistent with a majority of other sources). +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +\fI~\fP indicates a source whose time appears to have too much variability. +.RE +.RE +.sp +\fBName/IP address\fP +.RS 4 +This shows the name or the IP address of the source, or reference ID for reference +clocks. +.RE +.sp +\fBStratum\fP +.RS 4 +This shows the stratum of the source, as reported in its most recently +received sample. Stratum 1 indicates a computer with a locally attached +reference clock. A computer that is synchronised to a stratum 1 computer is +at stratum 2. A computer that is synchronised to a stratum 2 computer is at +stratum 3, and so on. +.RE +.sp +\fBPoll\fP +.RS 4 +This shows the rate at which the source is being polled, as a base\-2 +logarithm of the interval in seconds. Thus, a value of 6 would indicate that +a measurement is being made every 64 seconds. \fBchronyd\fP automatically varies +the polling rate in response to prevailing conditions. +.RE +.sp +\fBReach\fP +.RS 4 +This shows the source\(cqs reachability register printed as an octal number. The +register has 8 bits and is updated on every received or missed packet from +the source. A value of 377 indicates that a valid reply was received for all +from the last eight transmissions. +.RE +.sp +\fBLastRx\fP +.RS 4 +This column shows how long ago the last good sample (which is shown in the next +column) was received from the source. Measurements that failed some tests are +ignored. This is normally in seconds. The letters \fIm\fP, \fIh\fP, \fId\fP or \fIy\fP indicate +minutes, hours, days, or years. +.RE +.sp +\fBLast sample\fP +.RS 4 +This column shows the offset between the local clock and the source at the +last measurement. The number in the square brackets shows the actual measured +offset. This can be suffixed by \fIns\fP (indicating nanoseconds), \fIus\fP +(indicating microseconds), \fIms\fP (indicating milliseconds), or \fIs\fP (indicating +seconds). The number to the left of the square brackets shows the original +measurement, adjusted to allow for any slews applied to the local clock +since. The number following the \fI+/\-\fP indicator shows the margin of error in +the measurement. Positive offsets indicate that the local clock is ahead of +the source. +.RE +.RE +.sp +\fBsourcestats\fP [\fB\-v\fP] +.RS 4 +The \fBsourcestats\fP command displays information about the drift rate and offset +estimation process for each of the sources currently being examined by +\fBchronyd\fP. +.sp +The optional argument \fB\-v\fP can be specified, meaning \fIverbose\fP. In this case, +extra caption lines are shown as a reminder of the meanings of the columns. +.sp +An example report is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +210 Number of sources = 1 +Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev +=============================================================================== +foo.example.net 11 5 46m \-0.001 0.045 1us 25us +.fi +.if n \{\ +.RE +.\} +.sp +The columns are as follows: +.sp +\fBName/IP Address\fP +.RS 4 +This is the name or IP address of the NTP server (or peer) or reference ID of the +reference clock to which the rest of the line relates. +.RE +.sp +\fBNP\fP +.RS 4 +This is the number of sample points currently being retained for the server. +The drift rate and current offset are estimated by performing a linear +regression through these points. +.RE +.sp +\fBNR\fP +.RS 4 +This is the number of runs of residuals having the same sign following the +last regression. If this number starts to become too small relative to the +number of samples, it indicates that a straight line is no longer a good fit +to the data. If the number of runs is too low, \fBchronyd\fP discards older +samples and re\-runs the regression until the number of runs becomes +acceptable. +.RE +.sp +\fBSpan\fP +.RS 4 +This is the interval between the oldest and newest samples. If no unit is +shown the value is in seconds. In the example, the interval is 46 minutes. +.RE +.sp +\fBFrequency\fP +.RS 4 +This is the estimated residual frequency for the server, in parts per +million. In this case, the computer\(cqs clock is estimated to be running 1 part +in 10^9 slow relative to the server. +.RE +.sp +\fBFreq Skew\fP +.RS 4 +This is the estimated error bounds on \fBFreq\fP (again in parts per million). +.RE +.sp +\fBOffset\fP +.RS 4 +This is the estimated offset of the source. +.RE +.sp +\fBStd Dev\fP +.RS 4 +This is the estimated sample standard deviation. +.RE +.RE +.sp +\fBreselect\fP +.RS 4 +To avoid excessive switching between sources, \fBchronyd\fP can stay synchronised +to a source even when it is not currently the best one among the available +sources. +.sp +The \fBreselect\fP command can be used to force \fBchronyd\fP to reselect the best +synchronisation source. +.RE +.sp +\fBreselectdist\fP \fIdistance\fP +.RS 4 +The \fBreselectdist\fP command sets the reselection distance. It is equivalent to +the \fBreselectdist\fP directive in the +configuration file. +.RE +.SS "NTP sources" +.sp +\fBactivity\fP +.RS 4 +This command reports the number of servers and peers that are online and +offline. If the \fBauto_offline\fP option is used in specifying some of the servers +or peers, the \fBactivity\fP command can be useful for detecting when all of them +have entered the offline state after the network link has been disconnected. +.sp +The report shows the number of servers and peers in 5 states: +.sp +\fBonline\fP +.RS 4 +the server or peer is currently online (i.e. assumed by \fBchronyd\fP to be reachable) +.RE +.sp +\fBoffline\fP +.RS 4 +the server or peer is currently offline (i.e. assumed by \fBchronyd\fP to be +unreachable, and no measurements from it will be attempted.) +.RE +.sp +\fBburst_online\fP +.RS 4 +a burst command has been initiated for the server or peer and is being +performed; after the burst is complete, the server or peer will be returned to +the online state. +.RE +.sp +\fBburst_offline\fP +.RS 4 +a burst command has been initiated for the server or peer and is being +performed; after the burst is complete, the server or peer will be returned to +the offline state. +.RE +.sp +\fBunresolved\fP +.RS 4 +the name of the server or peer was not resolved to an address yet; this source is +not visible in the \fBsources\fP and \fBsourcestats\fP reports. +.RE +.RE +.sp +\fBntpdata\fP [\fIaddress\fP] +.RS 4 +The \fBntpdata\fP command displays the last valid measurement and other +NTP\-specific information about the specified NTP source, or all NTP sources if +no address was specified. An example of the output is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +Remote address : 203.0.113.15 (CB00710F) +Remote port : 123 +Local address : 203.0.113.74 (CB00714A) +Leap status : Normal +Version : 4 +Mode : Server +Stratum : 1 +Poll interval : 10 (1024 seconds) +Precision : \-24 (0.000000060 seconds) +Root delay : 0.000015 seconds +Root dispersion : 0.000015 seconds +Reference ID : 47505300 (GPS) +Reference time : Fri Nov 25 15:22:12 2016 +Offset : \-0.000060878 seconds +Peer delay : 0.000175634 seconds +Peer dispersion : 0.000000681 seconds +Response time : 0.000053050 seconds +Jitter asymmetry: +0.00 +NTP tests : 111 111 1111 +Interleaved : No +Authenticated : No +TX timestamping : Kernel +RX timestamping : Kernel +Total TX : 24 +Total RX : 24 +Total valid RX : 24 +.fi +.if n \{\ +.RE +.\} +.sp +The fields are explained as follows: +.sp +\fBRemote address\fP +.RS 4 +The IP address of the NTP server or peer, and the corresponding reference ID. +.RE +.sp +\fBRemote port\fP +.RS 4 +The UDP port number to which the request was sent. The standard NTP port is +123. +.RE +.sp +\fBLocal address\fP +.RS 4 +The local IP address which received the response, and the corresponding +reference ID. +.RE +.sp +\fBLeap status\fP, \fBVersion\fP, \fBMode\fP, \fBStratum\fP, \fBPoll interval\fP, \fBPrecision\fP, \fBRoot delay\fP, \fBRoot dispersion\fP, \fBReference ID\fP, \fBReference time\fP +.RS 4 +The NTP values from the last valid response. +.RE +.sp +\fBOffset\fP, \fBPeer delay\fP, \fBPeer dispersion\fP +.RS 4 +The measured values. +.RE +.sp +\fBResponse time\fP +.RS 4 +The time the server or peer spent in processing of the request and waiting +before sending the response. +.RE +.sp +\fBJitter asymmetry\fP +.RS 4 +The estimated asymmetry of network jitter on the path to the source. The +asymmetry can be between \-0.5 and 0.5. A negative value means the delay of +packets sent to the source is more variable than the delay of packets sent +from the source back. +.RE +.sp +\fBNTP tests\fP +.RS 4 +Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum +delay, delay ratio, delay dev ratio, and synchronisation loop. +.RE +.sp +\fBInterleaved\fP +.RS 4 +This shows if the response was in the interleaved mode. +.RE +.sp +\fBAuthenticated\fP +.RS 4 +This shows if the response was authenticated. +.RE +.sp +\fBTX timestamping\fP +.RS 4 +The source of the local transmit timestamp. Valid values are \fIDaemon\fP, +\fIKernel\fP, and \fIHardware\fP. +.RE +.sp +\fBRX timestamping\fP +.RS 4 +The source of the local receive timestamp. +.RE +.sp +\fBTotal TX\fP +.RS 4 +The number of packets sent to the source. +.RE +.sp +\fBTotal RX\fP +.RS 4 +The number of all packets received from the source. +.RE +.sp +\fBTotal valid RX\fP +.RS 4 +The number of valid packets received from the source. +.RE +.RE +.sp +\fBadd peer\fP \fIaddress\fP [\fIoption\fP]... +.RS 4 +The \fBadd peer\fP command allows a new NTP peer to be added whilst +\fBchronyd\fP is running. +.sp +Following the words \fBadd peer\fP, the syntax of the following +parameters and options is similar to that for the +\fBpeer\fP directive in the configuration file. +The following peer options can be set in the command: \fBport\fP, \fBminpoll\fP, +\fBmaxpoll\fP, \fBpresend\fP, \fBmaxdelayratio\fP, \fBmaxdelay\fP, \fBkey\fP. +.sp +An example of using this command is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +add peer foo.example.net minpoll 6 maxpoll 10 key 25 +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBadd server\fP \fIaddress\fP [\fIoption\fP]... +.RS 4 +The \fBadd server\fP command allows a new NTP server to be added whilst +\fBchronyd\fP is running. +.sp +Following the words \fBadd server\fP, the syntax of the following parameters and +options is similar to that for the \fBserver\fP +directive in the configuration file. +The following server options can be set in the command: \fBport\fP, \fBminpoll\fP, +\fBmaxpoll\fP, \fBpresend\fP, \fBmaxdelayratio\fP, \fBmaxdelay\fP, \fBkey\fP. +.sp +An example of using this command is shown below: +.sp +.if n \{\ +.RS 4 +.\} +.nf +add server foo.example.net minpoll 6 maxpoll 10 key 25 +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBdelete\fP \fIaddress\fP +.RS 4 +The \fBdelete\fP command allows an NTP server or peer to be removed +from the current set of sources. +.RE +.sp +\fBburst\fP \fIgood\fP/\fImax\fP [\fImask\fP/\fImasked\-address\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fIaddress\fP] +.RS 4 +The \fBburst\fP command tells \fBchronyd\fP to make a set of measurements to each of +its NTP sources over a short duration (rather than the usual periodic +measurements that it makes). After such a burst, \fBchronyd\fP will revert to the +previous state for each source. This might be either online, if the source was +being periodically measured in the normal way, or offline, if the source had +been indicated as being offline. (A source can be switched between the online +and offline states with the \fBonline\fP and \fBoffline\fP +commands.) +.sp +The \fImask\fP and \fImasked\-address\fP arguments are optional, in which case \fBchronyd\fP +will initiate a burst for all of its currently defined sources. +.sp +The arguments have the following meaning and format: +.sp +\fIgood\fP +.RS 4 +This defines the number of good measurements that \fBchronyd\fP will want to +obtain from each source. A measurement is good if it passes certain tests, +for example, the round trip time to the source must be acceptable. (This +allows \fBchronyd\fP to reject measurements that are likely to be bogus.) +.RE +.sp +\fImax\fP +.RS 4 +This defines the maximum number of measurements that \fBchronyd\fP will attempt +to make, even if the required number of good measurements has not been +obtained. +.RE +.sp +\fImask\fP +.RS 4 +This is an IP address with which the IP address of each of \fBchronyd\fP\(cqs +sources is to be masked. +.RE +.sp +\fImasked\-address\fP +.RS 4 +This is an IP address. If the masked IP address of a source matches this +value then the burst command is applied to that source. +.RE +.sp +\fImasked\-bits\fP +.RS 4 +This can be used with \fImasked\-address\fP for CIDR notation, which is a shorter +alternative to the form with mask. +.RE +.sp +\fIaddress\fP +.RS 4 +This is an IP address or a hostname. The burst command is applied only to +that source. +.RE +.RE +.sp + +.RS 4 +.sp +If no \fImask\fP or \fImasked\-address\fP arguments are provided, every source will be +matched. +.sp +An example of the two\-argument form of the command is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +burst 2/10 +.fi +.if n \{\ +.RE +.\} +.sp +This will cause \fBchronyd\fP to attempt to get two good measurements from each +source, stopping after two have been obtained, but in no event will it try more +than ten probes to the source. +.sp +Examples of the four\-argument form of the command are: +.sp +.if n \{\ +.RS 4 +.\} +.nf +burst 2/10 255.255.0.0/1.2.0.0 +burst 2/10 2001:db8:789a::/48 +.fi +.if n \{\ +.RE +.\} +.sp +In the first case, the two out of ten sampling will only be applied to sources +whose IPv4 addresses are of the form \fI1.2.x.y\fP, where \fIx\fP and \fIy\fP are +arbitrary. In the second case, the sampling will be applied to sources whose +IPv6 addresses have first 48 bits equal to \fI2001:db8:789a\fP. +.sp +Example of the three\-argument form of the command is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +burst 2/10 foo.example.net +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBmaxdelay\fP \fIaddress\fP \fIdelay\fP +.RS 4 +This allows the \fBmaxdelay\fP option for one of the sources to be modified, in the +same way as specifying the \fBmaxdelay\fP option for the +\fBserver\fP directive in the configuration file. +.RE +.sp +\fBmaxdelaydevratio\fP \fIaddress\fP \fIratio\fP +.RS 4 +This allows the \fBmaxdelaydevratio\fP option for one of the sources to be +modified, in the same way as specifying the \fBmaxdelaydevratio\fP option for the +\fBserver\fP directive in the configuration file. +.RE +.sp +\fBmaxdelayratio\fP \fIaddress\fP \fIratio\fP +.RS 4 +This allows the \fBmaxdelayratio\fP option for one of the sources to be modified, +in the same way as specifying the \fBmaxdelayratio\fP option for the +\fBserver\fP directive in the configuration file. +.RE +.sp +\fBmaxpoll\fP \fIaddress\fP \fImaxpoll\fP +.RS 4 +The \fBmaxpoll\fP command is used to modify the maximum polling interval for one of +the current set of sources. It is equivalent to the \fBmaxpoll\fP option in the +\fBserver\fP directive in the configuration file. +.sp +Note that the new maximum polling interval only takes effect after the next +measurement has been made. +.RE +.sp +\fBminpoll\fP \fIaddress\fP \fIminpoll\fP +.RS 4 +The \fBminpoll\fP command is used to modify the minimum polling interval for one of +the current set of sources. It is equivalent to the \fBminpoll\fP option in the +\fBserver\fP directive in the configuration file. +.sp +Note that the new minimum polling interval only takes effect after the next +measurement has been made. +.RE +.sp +\fBminstratum\fP \fIaddress\fP \fIminstratum\fP +.RS 4 +The \fBminstratum\fP command is used to modify the minimum stratum for one of the +current set of sources. It is equivalent to the \fBminstratum\fP option in the +\fBserver\fP directive in the configuration file. +.RE +.sp +\fBoffline\fP [\fIaddress\fP], \fBoffline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBoffline\fP [\fImask\fP/\fImasked\-address\fP] +.RS 4 +The \fBoffline\fP command is used to warn \fBchronyd\fP that the network connection to +a particular host or hosts is about to be lost, e.g. on computers with +intermittent connection to their time sources. +.sp +Another case where \fBoffline\fP could be used is where a computer serves time to a +local group of computers, and has a permanent connection to true time servers +outside the organisation. However, the external connection is heavily loaded at +certain times of the day and the measurements obtained are less reliable at +those times. In this case, it is probably most useful to determine the +gain or loss rate during the quiet periods and let the whole network coast through +the loaded periods. The \fBoffline\fP and \fBonline\fP commands can be used to achieve +this. +.sp +There are four forms of the \fBoffline\fP command. The first form is a wildcard, +meaning all sources. The second form allows an IP address mask and a masked +address to be specified. The third form uses CIDR notation. The fourth form +uses an IP address or a hostname. These forms are illustrated below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +offline +offline 255.255.255.0/1.2.3.0 +offline 2001:db8:789a::/48 +offline foo.example.net +.fi +.if n \{\ +.RE +.\} +.sp +The second form means that the \fBoffline\fP command is to be applied to any source +whose IPv4 address is in the \fI1.2.3\fP subnet. (The host\(cqs address is logically +and\-ed with the mask, and if the result matches the \fImasked\-address\fP the host +is processed.) The third form means that the command is to be applied to all +sources whose IPv6 addresses have their first 48 bits equal to \fI2001:db8:789a\fP. The +fourth form means that the command is to be applied only to that one source. +.sp +The wildcard form of the address is equivalent to: +.sp +.if n \{\ +.RS 4 +.\} +.nf +offline 0.0.0.0/0.0.0.0 +offline ::/0 +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBonline\fP [\fIaddress\fP], \fBonline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBonline\fP [\fImask\fP/\fImasked\-address\fP] +.RS 4 +The \fBonline\fP command is opposite in function to the \fBoffline\fP +command. It is used to advise \fBchronyd\fP that network connectivity to a +particular source or sources has been restored. +.sp +The syntax is identical to that of the \fBoffline\fP command. +.RE +.sp +\fBonoffline\fP +.RS 4 +The \fBonoffline\fP command tells \fBchronyd\fP to switch all sources to the online or +offline status according to the current network configuration. A source is +considered online if it is possible to send requests to it, i.e. a route to the +network is present. +.RE +.sp +\fBpolltarget\fP \fIaddress\fP \fIpolltarget\fP +.RS 4 +The \fBpolltarget\fP command is used to modify the poll target for one of the +current set of sources. It is equivalent to the \fBpolltarget\fP option in the +\fBserver\fP directive in the configuration file. +.RE +.sp +\fBrefresh\fP +.RS 4 +The \fBrefresh\fP command can be used to force \fBchronyd\fP to resolve the names of +configured sources to IP addresses again, e.g. after suspending and resuming +the machine in a different network. +.sp +Sources that stop responding will be replaced with newly resolved addresses +automatically after 8 polling intervals, but this command can still be useful +to replace them immediately and not wait until they are marked as unreachable. +.RE +.SS "Manual time input" +.sp +\fBmanual\fP \fBon\fP, \fBmanual\fP \fBoff\fP, \fBmanual\fP \fBdelete\fP \fIindex\fP, \fBmanual\fP \fBlist\fP, \fBmanual\fP \fBreset\fP +.RS 4 +The manual command enables and disables use of the \fBsettime\fP +command, and is used to modify the behaviour of the manual clock driver. +.sp +The \fBon\fP form of the command enables use of the \fBsettime\fP command. +.sp +The \fBoff\fP form of the command disables use of the \fBsettime\fP command. +.sp +The \fBlist\fP form of the command lists all the samples currently stored in +\fBchronyd\fP. The output is illustrated below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +210 n_samples = 1 +# Date Time(UTC) Slewed Original Residual +==================================================== + 0 27Jan99 22:09:20 0.00 0.97 0.00 +.fi +.if n \{\ +.RE +.\} +.sp +The columns are as as follows: +.sp +.RS 4 +.ie n \{\ +\h'-04' 1.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 1." 4.2 +.\} +The sample index (used for the \fBmanual delete\fP command). +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 2.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 2." 4.2 +.\} +The date and time of the sample. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 3.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 3." 4.2 +.\} +The system clock error when the timestamp was entered, adjusted to allow +for changes made to the system clock since. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 4.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 4." 4.2 +.\} +The system clock error when the timestamp was entered, as it originally was +(without allowing for changes to the system clock since). +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 5.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 5." 4.2 +.\} +The regression residual at this point, in seconds. This allows \(oqoutliers\(cq +to be easily spotted, so that they can be deleted using the \fBmanual delete\fP +command. +.RE +.RE +.sp + +.RS 4 +.sp +The \fBdelete\fP form of the command deletes a single sample. The parameter is the +index of the sample, as shown in the first column of the output from \fBmanual +list\fP. Following deletion of the data point, the current error and drift rate +are re\-estimated from the remaining data points and the system clock trimmed if +necessary. This option is intended to allow \(oqoutliers\(cq to be discarded, i.e. +samples where the administrator realises they have entered a very poor +timestamp. +.sp +The \fBreset\fP form of the command deletes all samples at once. The system clock +is left running as it was before the command was entered. +.RE +.sp +\fBsettime\fP \fItime\fP +.RS 4 +The \fBsettime\fP command allows the current time to be entered manually, if this +option has been configured into \fBchronyd\fP. (It can be configured either with +the \fBmanual\fP directive in the configuration file, +or with the \fBmanual\fP command of \fBchronyc\fP.) +.sp +It should be noted that the computer\(cqs sense of time will only be as accurate +as the reference you use for providing this input (e.g. your watch), as well as +how well you can time the press of the return key. +.sp +Providing your computer\(cqs time zone is set up properly, you will be able to +enter a local time (rather than UTC). +.sp +The response to a successful \fBsettime\fP command indicates the amount that the +computer\(cqs clock was wrong. It should be apparent from this if you have entered +the time wrongly, e.g. with the wrong time zone. +.sp +The rate of drift of the system clock is estimated by a regression process +using the entered measurement and all previous measurements entered during the +present run of \fBchronyd\fP. However, the entered measurement is used for +adjusting the current clock offset (rather than the estimated intercept from +the regression, which is ignored). Contrast what happens with the +\fBmanual delete\fP command, where the intercept is used to set the +current offset (since there is no measurement that has just been entered in +that case). +.sp +The time is parsed by the public domain \fIgetdate\fP algorithm. Consequently, you +can only specify time to the nearest second. +.sp +Examples of inputs that are valid are shown below: +.sp +.if n \{\ +.RS 4 +.\} +.nf +settime 16:30 +settime 16:30:05 +settime Nov 21, 2015 16:30:05 +.fi +.if n \{\ +.RE +.\} +.sp +For a full description of getdate, see the getdate documentation +(bundled, for example, with the source for GNU tar). +.RE +.SS "NTP access" +.sp +\fBaccheck\fP \fIaddress\fP +.RS 4 +This command allows you to check whether client NTP access is allowed from a +particular host. +.sp +Examples of use, showing a named host and a numeric IP address, are as follows: +.sp +.if n \{\ +.RS 4 +.\} +.nf +accheck foo.example.net +accheck 1.2.3.4 +accheck 2001:db8::1 +.fi +.if n \{\ +.RE +.\} +.sp +This command can be used to examine the effect of a series of \fBallow\fP, \fBallow +all\fP, \fBdeny\fP, and \fBdeny all\fP commands specified either via \fBchronyc\fP, or in +\fBchronyd\fP\(cqs configuration file. +.RE +.sp +\fBclients\fP +.RS 4 +This command shows a list of clients that have accessed the server, through +either the NTP or command ports. It does not include accesses over +the Unix domain command socket. There are no arguments. +.sp +An example of the output is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +Hostname NTP Drop Int IntL Last Cmd Drop Int Last +=============================================================================== +localhost 2 0 2 \- 133 15 0 \-1 7 +foo.example.net 12 0 6 \- 23 0 0 \- \- +.fi +.if n \{\ +.RE +.\} +.sp +Each row shows the data for a single host. Only hosts that have passed the host +access checks (set with the \fBallow\fP, \fBdeny\fP, +\fBcmdallow\fP and \fBcmddeny\fP commands or configuration +file directives) are logged. The intervals are displayed as a power of 2 in +seconds. +.sp +The columns are as follows: +.sp +.RS 4 +.ie n \{\ +\h'-04' 1.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 1." 4.2 +.\} +The hostname of the client. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 2.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 2." 4.2 +.\} +The number of NTP packets received from the client. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 3.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 3." 4.2 +.\} +The number of NTP packets dropped to limit the response rate. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 4.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 4." 4.2 +.\} +The average interval between NTP packets. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 5.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 5." 4.2 +.\} +The average interval between NTP packets after limiting the response rate. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 6.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 6." 4.2 +.\} +Time since the last NTP packet was received +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 7.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 7." 4.2 +.\} +The number of command packets received from the client. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 8.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 8." 4.2 +.\} +The number of command packets dropped to limit the response rate. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 9.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 9." 4.2 +.\} +The average interval between command packets. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 10.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 10." 4.2 +.\} +Time since the last command packet was received. +.RE +.RE +.sp +\fBserverstats\fP +.RS 4 +The \fBserverstats\fP command displays how many valid NTP and command requests +\fBchronyd\fP as a server received from clients, how many of them were dropped to +limit the response rate as configured by the +\fBratelimit\fP and +\fBcmdratelimit\fP directives, and how many +client log records were dropped due to the memory limit configured by the +\fBclientloglimit\fP directive. An example of +the output is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +NTP packets received : 1598 +NTP packets dropped : 8 +Command packets received : 19 +Command packets dropped : 0 +Client log records dropped : 0 +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBallow\fP [\fBall\fP] [\fIsubnet\fP] +.RS 4 +The effect of the allow command is identical to the +\fBallow\fP directive in the configuration file. +.sp +The syntax is illustrated in the following examples: +.sp +.if n \{\ +.RS 4 +.\} +.nf +allow foo.example.net +allow all 1.2 +allow 3.4.5 +allow 6.7.8/22 +allow 6.7.8.9/22 +allow 2001:db8:789a::/48 +allow 0/0 +allow ::/0 +allow +allow all +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBdeny\fP [\fBall\fP] [\fIsubnet\fP] +.RS 4 +The effect of the allow command is identical to the +\fBdeny\fP directive in the configuration file. +.sp +The syntax is illustrated in the following examples: +.sp +.if n \{\ +.RS 4 +.\} +.nf +deny foo.example.net +deny all 1.2 +deny 3.4.5 +deny 6.7.8/22 +deny 6.7.8.9/22 +deny 2001:db8:789a::/48 +deny 0/0 +deny ::/0 +deny +deny all +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBlocal\fP [\fIoption\fP]..., \fBlocal\fP \fBoff\fP +.RS 4 +The \fBlocal\fP command allows \fBchronyd\fP to be told that it is to appear as a +reference source, even if it is not itself properly synchronised to an external +source. (This can be used on isolated networks, to allow one computer to be a +master time server with the other computers slaving to it.) +.sp +The first form enables the local reference mode on the host. The syntax is +identical to the \fBlocal\fP directive in the +configuration file. +.sp +The second form disables the local reference mode. +.RE +.sp +\fBsmoothing\fP +.RS 4 +The \fBsmoothing\fP command displays the current state of the NTP server time +smoothing, which can be enabled with the +\fBsmoothtime\fP directive. An example of the +output is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +Active : Yes +Offset : +1.000268817 seconds +Frequency : \-0.142859 ppm +Wander : \-0.010000 ppm per second +Last update : 17.8 seconds ago +Remaining time : 19988.4 seconds +.fi +.if n \{\ +.RE +.\} +.sp +The fields are explained as follows: +.sp +\fBActive\fP +.RS 4 +This shows if the server time smoothing is currently active. Possible values +are \fIYes\fP and \fINo\fP. If the \fBleaponly\fP option is included in the \fBsmoothtime\fP +directive, \fI(leap second only)\fP will be shown on the line. +.RE +.sp +\fBOffset\fP +.RS 4 +This is the current offset applied to the time sent to NTP clients. Positive +value means the clients are getting time that\(cqs ahead of true time. +.RE +.sp +\fBFrequency\fP +.RS 4 +The current frequency offset of the served time. Negative value means the +time observed by clients is running slower than true time. +.RE +.sp +\fBWander\fP +.RS 4 +The current frequency wander of the served time. Negative value means the +time observed by clients is slowing down. +.RE +.sp +\fBLast update\fP +.RS 4 +This field shows how long ago the time smoothing process was updated, e.g. +\fBchronyd\fP accumulated a new measurement. +.RE +.sp +\fBRemaining time\fP +.RS 4 +The time it would take for the smoothing process to get to zero offset and +frequency if there were no more updates. +.RE +.RE +.sp +\fBsmoothtime\fP \fBactivate\fP, \fBsmoothtime\fP \fBreset\fP +.RS 4 +The \fBsmoothtime\fP command can be used to activate or reset the server time +smoothing process if it is configured with the +\fBsmoothtime\fP directive. +.RE +.SS "Monitoring access" +.sp +\fBcmdaccheck\fP \fIaddress\fP +.RS 4 +This command is similar to the \fBaccheck\fP command, except that it is +used to check whether monitoring access is permitted from a named host. +.sp +Examples of use are as follows: +.sp +.if n \{\ +.RS 4 +.\} +.nf +cmdaccheck foo.example.net +cmdaccheck 1.2.3.4 +cmdaccheck 2001:db8::1 +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBcmdallow\fP [\fBall\fP] [\fIsubnet\fP] +.RS 4 +This is similar to the \fBallow\fP command, except that it is used to +allow particular hosts or subnets to use \fBchronyc\fP to monitor with \fBchronyd\fP on +the current host. +.RE +.sp +\fBcmddeny\fP [\fBall\fP] [\fIsubnet\fP] +.RS 4 +This is similar to the \fBdeny\fP command, except that it is used to allow +particular hosts or subnets to use \fBchronyc\fP to monitor \fBchronyd\fP on the +current host. +.RE +.SS "Real\-time clock (RTC)" +.sp +\fBrtcdata\fP +.RS 4 +The \fBrtcdata\fP command displays the current RTC parameters. +.sp +An example output is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +RTC ref time (GMT) : Sat May 30 07:25:56 2015 +Number of samples : 10 +Number of runs : 5 +Sample span period : 549 +RTC is fast by : \-1.632736 seconds +RTC gains time at : \-107.623 ppm +.fi +.if n \{\ +.RE +.\} +.sp +The fields have the following meaning: +.sp +\fBRTC ref time (GMT)\fP +.RS 4 +This is the RTC reading the last time its error was measured. +.RE +.sp +\fBNumber of samples\fP +.RS 4 +This is the number of previous measurements being used to determine the RTC +gain or loss rate. +.RE +.sp +\fBNumber of runs\fP +.RS 4 +This is the number of runs of residuals of the same sign following the +regression fit for (RTC error) versus (RTC time). A value which is small +indicates that the measurements are not well approximated by a linear model, +and that the algorithm will tend to delete the older measurements to improve +the fit. +.RE +.sp +\fBSample span period\fP +.RS 4 +This is the period that the measurements span (from the oldest to the +newest). Without a unit the value is in seconds; suffixes \fIm\fP for minutes, +\fIh\fP for hours, \fId\fP for days or \fIy\fP for years can be used. +.RE +.sp +\fBRTC is fast by\fP +.RS 4 +This is the estimate of how many seconds fast the RTC when it thought +the time was at the reference time (above). If this value is large, you +might (or might not) want to use the \fBtrimrtc\fP command to bring the +RTC into line with the system clock. (Note, a large error will not affect +\fBchronyd\fP\(cqs operation, unless it becomes so big as to start causing rounding +errors.) +.RE +.sp +\fBRTC gains time at\fP +.RS 4 +This is the amount of time gained (positive) or lost (negative) by the real +time clock for each second that it ticks. It is measured in parts per +million. So if the value shown was +1, suppose the RTC was exactly right when +it crosses a particular second boundary. Then it would be 1 microsecond fast +when it crosses its next second boundary. +.RE +.RE +.sp +\fBtrimrtc\fP +.RS 4 +The \fBtrimrtc\fP command is used to correct the system\(cqs real\-time clock (RTC) to +the main system clock. It has no effect if the error between the two clocks is +currently estimated at less than a second. +.sp +The command takes no arguments. It performs the following steps (if the RTC is +more than 1 second away from the system clock): +.sp +.RS 4 +.ie n \{\ +\h'-04' 1.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 1." 4.2 +.\} +Remember the currently estimated gain or loss rate of the RTC and flush the +previous measurements. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 2.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 2." 4.2 +.\} +Step the real\-time clock to bring it within a second of the system clock. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 3.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 3." 4.2 +.\} +Make several measurements to accurately determine the new offset between +the RTC and the system clock (i.e. the remaining fraction of a second +error). +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04' 4.\h'+01'\c +.\} +.el \{\ +.sp -1 +.IP " 4." 4.2 +.\} +Save the RTC parameters to the RTC file (specified with the +\fBrtcfile\fP directive in the configuration file). +.RE +.RE +.sp + +.RS 4 +.sp +The last step is done as a precaution against the computer suffering a power +failure before either the daemon exits or the \fBwritertc\fP command +is issued. +.sp +\fBchronyd\fP will still work perfectly well both whilst operating and across +machine reboots even if the \fBtrimrtc\fP command is never used (and the RTC is +allowed to drift away from true time). The \fBtrimrtc\fP command is provided as a +method by which it can be corrected, in a manner compatible with \fBchronyd\fP +using it to maintain accurate time across machine reboots. +.sp +The \fBtrimrtc\fP command can be executed automatically by \fBchronyd\fP with the +\fBrtcautotrim\fP directive in the configuration +file. +.RE +.sp +\fBwritertc\fP +.RS 4 +The \fBwritertc\fP command writes the currently estimated error and gain or loss rate +parameters for the RTC to the RTC file (specified with the +\fBrtcfile\fP directive). This information is also +written automatically when \fBchronyd\fP is killed (by the SIGHUP, SIGINT, SIGQUIT +or SIGTERM signals) or when the \fBtrimrtc\fP command is issued. +.RE +.SS "Other daemon commands" +.sp +\fBcyclelogs\fP +.RS 4 +The \fBcyclelogs\fP command causes all of \fBchronyd\fP\(cqs open log files to be closed +and re\-opened. This allows them to be renamed so that they can be periodically +purged. An example of how to do this is shown below. +.sp +.if n \{\ +.RS 4 +.\} +.nf +# mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log +# chronyc cyclelogs +# ls \-l /var/log/chrony +\-rw\-r\-\-r\-\- 1 root root 0 Jun 8 18:17 measurements.log +\-rw\-r\-\-r\-\- 1 root root 12345 Jun 8 18:17 measurements1.log +# rm \-f measurements1.log +.fi +.if n \{\ +.RE +.\} +.RE +.sp +\fBdump\fP +.RS 4 +The \fBdump\fP command causes \fBchronyd\fP to write its current history of +measurements for each of its sources to dump files in the directory specified +in the configuration file by the \fBdumpdir\fP +directive. Note that \fBchronyd\fP does this automatically when it exits. This +command is mainly useful for inspection of the history whilst \fBchronyd\fP is +running. +.RE +.sp +\fBrekey\fP +.RS 4 +The \fBrekey\fP command causes \fBchronyd\fP to re\-read the key file specified in the +configuration file by the \fBkeyfile\fP directive. +.RE +.sp +\fBshutdown\fP +.RS 4 +The \fBshutdown\fP command causes \fBchronyd\fP to exit. This is equivalent to sending +the process the SIGTERM signal. +.RE +.SS "Client commands" +.sp +\fBdns\fP \fIoption\fP +.RS 4 +The \fBdns\fP command configures how hostnames and IP addresses are resolved in +\fBchronyc\fP. IP addresses can be resolved to hostnames when printing results of +\fBsources\fP, \fBsourcestats\fP, \fBtracking\fP +and \fBclients\fP commands. Hostnames are resolved in commands that +take an address as argument. +.sp +There are five options: +.sp +\fBdns \-n\fP +.RS 4 +Disables resolving IP addresses to hostnames. Raw IP addresses will be +displayed. +.RE +.sp +\fBdns +n\fP +.RS 4 +Enables resolving IP addresses to hostnames. This is the default unless +\fBchronyc\fP was started with \fB\-n\fP option. +.RE +.sp +\fBdns \-4\fP +.RS 4 +Resolves hostnames only to IPv4 addresses. +.RE +.sp +\fBdns \-6\fP +.RS 4 +Resolves hostnames only to IPv6 addresses. +.RE +.sp +\fBdns \-46\fP +.RS 4 +Resolves hostnames to both address families. This is the default behaviour +unless \fBchronyc\fP was started with the \fB\-4\fP or \fB\-6\fP option. +.RE +.RE +.sp +\fBtimeout\fP \fItimeout\fP +.RS 4 +The \fBtimeout\fP command sets the initial timeout for \fBchronyc\fP requests in +milliseconds. If no response is received from \fBchronyd\fP, the timeout is doubled +and the request is resent. The maximum number of retries is configured with the +\fBretries\fP command. +.sp +By default, the timeout is 1000 milliseconds. +.RE +.sp +\fBretries\fP \fIretries\fP +.RS 4 +The \fBretries\fP command sets the maximum number of retries for \fBchronyc\fP requests +before giving up. The response timeout is controlled by the +\fBtimeout\fP command. +.sp +The default is 2. +.RE +.sp +\fBkeygen\fP [\fIid\fP [\fItype\fP [\fIbits\fP]]] +.RS 4 +The \fBkeygen\fP command generates a key that can be added to the +key file (specified with the \fBkeyfile\fP directive) +to allow NTP authentication between server and client, or peers. The key is +generated from the \fI/dev/urandom\fP device and it is printed to standard output. +.sp +The command has three optional arguments. The first argument is the key number +(by default 1), which will be specified with the \fBkey\fP option of the \fBserver\fP +or \fBpeer\fP directives in the configuration file. The second argument is the hash +function (by default SHA1 or MD5 if SHA1 is not available) and the third +argument is the number of bits the key should have, between 80 and 4096 bits +(by default 160 bits). +.sp +An example is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +keygen 73 SHA1 256 +.fi +.if n \{\ +.RE +.\} +.sp +which generates a 256\-bit SHA1 key with number 73. The printed line should +then be securely transferred and added to the key files on both server and +client, or peers. +.RE +.sp +\fBexit\fP, \fBquit\fP +.RS 4 +The \fBexit\fP and \fBquit\fP commands exit from \fBchronyc\fP and return the user to the shell. +.RE +.sp +\fBhelp\fP +.RS 4 +The \fBhelp\fP command displays a summary of the commands and their arguments. +.RE +.SH "SEE ALSO" +.sp +\fBchrony.conf(5)\fP, \fBchronyd(8)\fP +.SH "BUGS" +.sp +For instructions on how to report bugs, please visit +.URL "https://chrony.tuxfamily.org/" "" "." +.SH "AUTHORS" +.sp +chrony was written by Richard Curnow, Miroslav Lichvar, and others.
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