CHRONYC(1) User manual CHRONYC(1) NAME - chronyc - chrony SYNOPSIS - chronyc [OPTION]... [COMMAND]... DESCRIPTION - chronyc chronyd . chronyc . chronyc> . chronyc . chronyc chronyd : (IPv4 IPv6) (Unix domain socket) root chrony . chronyc . /var/run/chrony/chronyd.sock . ( chronyc root ) 127.0.0.1 ::1 . chronyd : activity manual list rtcdata smoothing sourcename sources sourcestats tracking waitsync. chronyd cmdallow chronyd cmdallow chronyc . localhost (127.0.0.1 ::1) . opencommands . chronyd . chronyd `Not authorised' localhost . chronyd chronyc chronyd . OPTIONS - -4 IPv4 . -6 IPv6 . -n IP DNS. . -N IP NTP chronyc . -n -N DNS . -c (CSV) . DNS (epoch) . -e chronyc . -d chronyc . -m . . . -h host chronyc . IP . (fallback) . /var/run/chrony/chronyd.sock,127.0.0.1,::1 chronyc . ( root) 127.0.0.1 ::1 . -p port UDP chronyd . 323 . -u user chronyc root . root 0 chronyc . root . -f file . -a . -v, --version chronyc . --help chronyc . (COMMANDS) chronyc . (System clock) tracking tracking . . Reference ID : CB00710F (ntp1.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 : Reference ID ( IP) . IPv4 IPv6 MD5 . 7F7F0101 IP (local) ( local chronyc local ). . (quad-dotted) IPv4 . Stratum (stratum) . stratum-1 ( ntp1.example.net stratum-2 stratum-1 ). Ref time ( UTC) . System time (offset) NTP . NTP () chronyd NTP . NTP . (steps) ( maxslewrate) . . makestep makestep . chronyc NTP . Last offset . ( ) . RMS offset . Frequency <<>> (frequency) chronyd . ppm ( ) . 1 ppm . Residual freq << >> . . . ( <> ) . . . Skew . Root delay stratum-1 . Root dispersion stratum-1 . . ( stratum-1) : clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay) Update interval . Leap status Normal Insert second Delete second Not synchronised . makestep, makestep threshold limit chronyd . (slewing) . makestep . . chronyd . makestep . : ( ) . burst chronyd . makestep 0.1 1 burst 1/2 : . ( chronyd .) maxupdateskew skew-in-ppm maxupdateskew . waitsync [max-tries [max-correction [max-skew [interval]]]] waitsync chronyd . . . 0 . ( ppm) tracking System time Skew . . . 10 . : waitsync 60 0.01 10 (60 10 ) chronyd 10 . (Time sources) sources [-a] [-v] chronyd . -a . ID#XXXXXXXXXX . -v . . MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== #* GPS0 0 4 377 11 -479ns[ -621ns] +/- 134ns ^? ntp1.example.net 2 6 377 23 -923us[ -924us] +/- 43ms ^+ ntp2.example.net 1 6 377 21 -2629us[-2619us] +/- 86ms : M . ^ = (peer) # . S . o * . o + . o - . o x chronyd (falseticker) ( trust ). o ~ . o ? ( ) . selectdata . Name/IP address IP (reference ID) . Stratum (stratum) . . . . Poll . . chronyd . Reach ( ) . NTP ( ) . . . LastRx ( ) . . . m h d y . Last sample (offset) . . ns () us () ms () s () . (slews) . . +/- ( NTP root distance) . sourcestats [-a] [-v] sourcestats (drift rate) chronyd . -a . ID#XXXXXXXXXX . -v . . : Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev =============================================================================== ntp1.example.net 11 5 46m -0.001 0.045 1us 25us : Name/IP Address IP NTP ( ) . NP . . NR (runs of residuals) . . chronyd . Span . . . Frequency (ppm) . ^ . Freq Skew Freq ( ). Offset . Std Dev . selectdata [-a] [-v] selectdata . -a . -v . . S Name/IP Address Auth COpts EOpts Last Score Interval Leap ======================================================================= D ntp1.example.net Y ----- --TR- 4 1.0 -61ms +62ms N * ntp2.example.net N ----- ----- 0 1.0 -6846us +7305us N + ntp3.example.net N ----- ----- 10 1.0 -7381us +7355us N : S . sources . : o N - noselect . o M - . o s - . o d - ( maxdistance ). o ~ - (jitter) ( maxjitter ). o w - M . o S - ( maxunreach). o O - (orphan stratum) ( local ). o T - trust . o x - ( falseticker). : o W - ( minsources require ). o P - prefer . o U - ( ). o D - ( ) ( combinelimit). : o + - . o * - ( ) . Name/IP address IP NTP . Auth . Y N . COpts . o N noselect . o P prefer . o T trust . o R require . EOpts ( authselectmode) . COpts . Last . Score * . . * . . Interval . Leap . o N ( ) . o + . o - . o ? ( ). selectopts address|refid [+|-option]... selectopts NTP IP ( ID#XXXXXXXXXX ) . + - . selectdata . reselect . . selectopts 1.2.3.4 -noselect +prefer selectopts GPS +trust reselect chronyd . reselect chronyd . reselectdist distance reselectdist . reselectdist . offset address|refid offset offset NTP IP ( ID#XXXXXXXXXX ) . offset server refclock . NTP (NTP sources) activity (peers) . auto_offline activity . : online ( chronyd ) offline ( chronyd .) burst_online burst . burst_offline burst . unresolved sources sourcestats . authdata [-a] authdata NTP . -a . . Name/IP address Mode KeyID Type KLen Last Atmp NAK Cook CLen ========================================================================= ntp1.example.net NTS 1 15 256 135m 0 0 8 100 ntp2.example.net SK 30 13 128 - 0 0 0 0 ntp3.example.net - 0 0 0 - 0 0 0 0 : Name/IP address IP . Mode NTP . NTS (Network Time Security) SK (symmetric key) - . KeyID . . NTS NTS-KE . Type . . NTS (AEAD) NTS-KE . : o 1: MD5 o 2: SHA1 o 3: SHA256 o 4: SHA384 o 5: SHA512 o 6: SHA3-224 o 7: SHA3-256 o 8: SHA3-384 o 9: SHA3-512 o 10: TIGER o 11: WHIRLPOOL o 13: AES128 o 14: AES256 o 15: AEAD-AES-SIV-CMAC-256 o 30: AEAD-AES-128-GCM-SIV KLen . Last . m h d y . Atmp . . NAK NTS NAK . NAK chronyd . Cook NTS chronyd . . CLen NTS . ntpdata [address] ntpdata NTP NTP NTP ( ) . . 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 Total good RX : 22 Total kernel TX : 24 Total kernel RX : 24 Total HW TX : 0 Total HW RX : 0 : Remote address IP NTP (reference ID) . Remote port UDP . NTP . Local address IP . Leap status, Version, Mode, Stratum, Poll interval, Precision, Root delay, Root dispersion, Reference ID, Reference time NTP . Offset, Peer delay, Peer dispersion . Response time . Jitter asymmetry (jitter) . -0.5 0.5 . . NTP tests RFC 5905 ( ) . Interleaved (interleaved mode) . Authenticated . TX timestamping . Daemon Kernel Hardware . RX timestamping . Total TX . Total RX . Total valid RX NTP . Total good RX NTP NTP . Total kernel TX . Total kernel RX . Total HW TX (NIC) . Total HW RX (NIC) . add peer name [option]... add peer NTP chronyd . add peer peer . . add peer ntp1.example.net minpoll 6 maxpoll 10 key 25 add pool name [option]... add pool (pool) NTP chronyd . add pool pool . : add pool ntp1.example.net maxsources 3 iburst add server name [option]... add server NTP chronyd . add server server . : add server ntp1.example.net minpoll 6 maxpoll 10 key 25 delete address delete NTP . burst good/max [mask/masked-address], burst good/max [masked-address/masked-bits], burst good/max [address] burst chronyd NTP ( ). chronyd . ( ) ( ). ( online offline .) mask masked-address chronyd . : good chronyd . . ( chronyd .) max chronyd . mask IP IP chronyd's . masked-address IP . IP burst . masked-bits masked-address CIDR mask . address IP . burst . mask masked-address . : burst 2/10 chronyd . : burst 2/10 255.255.0.0/1.2.0.0 burst 2/10 2001:db8:789a::/48 IPv4 1.2.x.y x y . IPv6 2001:db8:789a . : burst 2/10 ntp1.example.net maxdelay address delay maxdelay maxdelay server . maxdelaydevratio address ratio maxdelaydevratio maxdelaydevratio server . maxdelayratio address ratio maxdelayratio maxdelayratio server . maxpoll address maxpoll maxpoll (polling) . maxpoll server . . minpoll address minpoll minpoll (polling) . minpoll server . . minstratum address minstratum minstratum (stratum) . minstratum server . offline [address], offline [masked-address/masked-bits], offline [mask/masked-address] offline chronyd . offline . . . offline online . offline . (wildcard) ( ). IP . CIDR . IP . . offline offline 255.255.255.0/1.2.3.0 offline 2001:db8:789a::/48 offline ntp1.example.net offline IPv4 1.2.3 . ( AND masked-address .) IPv6 2001:db8:789a . . : offline 0.0.0.0/0.0.0.0 offline ::/0 online [address], online [masked-address/masked-bits], online [mask/masked-address] online offline . chronyd . offline . onoffline onoffline chronyd . (route) . polltarget address polltarget polltarget (poll target) . polltarget server . refresh refresh chronyd NTP IP . . . IPv4 IPv6 DNS ( pool.ntp.org) . reload sources reload sources chronyd *.sources sourcedir . ( ) . . sourcename address sourcename NTP add . -N . NTP (pool). (Manual time input) manual on, manual off, manual delete index, manual list, manual reset manual settime . on settime . off settime . list chronyd . . 210 n_samples = 1 # Date Time(UTC) Slewed Original Residual ==================================================== 0 27Jan99 22:09:20 0.00 0.97 0.00 : 1. (index) ( manual delete). 2. . 3. . 4. ( ). 5. . << >> (`outliers') manual delete . delete . manual list . (drift rate) (trim) . << >> (`outliers') . reset . . settime time settime chronyd . ( manual manual chronyc .) ( ) return . ( UTC) . settime . . chronyd . ( ). manual delete ( ). getdate . . : settime 16:30 settime 16:30:05 settime Nov 21, 2015 16:30:05 getdate getdate ( GNU tar ). (NTP access) accheck address NTP . IP : accheck ntp1.example.net accheck 1.2.3.4 accheck 2001:db8::1 allow allow all deny deny all chronyc chronyd . clients [-p packets] [-k] [-r] NTP NTS-KE . (Unix domain socket) . -p NTP NTS-KE . . -k NTS-KE . -r chronyd . : Hostname NTP Drop Int IntL Last Cmd Drop Int Last =============================================================================== localhost 2 0 2 - 133 15 0 -1 7 ntp1.example.net 12 0 6 - 23 0 0 - - . ( allow deny cmdallow cmddeny). . : 1. . 2. NTP . 3. NTP . 4. NTP. 5. NTP . 6. NTP. 7. NTS-KE / . 8. NTS-KE . 9. NTS-KE. 10. / NTS-KE. serverstats serverstats NTP . . NTP packets received : 1598 NTP packets dropped : 8 Command packets received : 19 Command packets dropped : 0 Client log records dropped : 0 NTS-KE connections accepted: 3 NTS-KE connections dropped : 0 Authenticated NTP packets : 189 Interleaved NTP packets : 43 NTP timestamps held : 44 NTP timestamp span : 120 NTP daemon RX timestamps : 0 NTP daemon TX timestamps : 1537 NTP kernel RX timestamps : 1590 NTP kernel TX timestamps : 43 NTP hardware RX timestamps : 0 NTP hardware TX timestamps : 0 : NTP packets received NTP . NTP packets dropped NTP ( ratelimit). Command packets received . Command packets dropped ( cmdratelimit). Client log records dropped ( clientloglimit). NTS-KE connections accepted NTS-KE . NTS-KE connections dropped NTS-KE ( ntsratelimit). Authenticated NTP packets NTP ( NTS). Interleaved NTP packets NTP (interleaved) . NTP timestamps held . NTP timestamp span ( ) NTP . NTP daemon RX timestamps NTP . NTP daemon TX timestamps NTP . NTP kernel RX timestamps NTP . NTP kernel TX timestamps NTP ( ) . NTP hardware RX timestamps NTP (NIC) . NTP hardware TX timestamps NTP ( ) (NIC) . allow [all] [subnet] allow allow . : allow 1.2.3.4 allow all 3.4.5.0/24 allow 2001:db8:789a::/48 allow 0/0 allow ::/0 allow allow all deny [all] [subnet] allow deny . : deny 1.2.3.4 deny all 3.4.5.0/24 deny 2001:db8:789a::/48 deny 0/0 deny ::/0 deny deny all local [option]..., local off local chronyd . . . local . . smoothing smoothing NTP smoothtime . . 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 : Active . Yes No . leaponly smoothtime (leap second only) . Offset NTP . . Frequency . . Wander (wander) . . Last update chronyd . Remaining time . smoothtime activate, smoothtime reset smoothtime smoothtime . (Monitoring access) cmdaccheck address accheck . : cmdaccheck ntp1.example.net cmdaccheck 1.2.3.4 cmdaccheck 2001:db8::1 cmdallow [all] [subnet] allow chronyc chronyd . cmddeny [all] [subnet] deny chronyc chronyd . (Real-time clock - RTC) rtcdata rtcdata RTC . : 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 : RTC ref time (GMT) RTC . Number of samples RTC . Number of runs (runs) ( RTC) ( RTC) . . Sample span period ( ). m h d y . RTC is fast by RTC ( ) . ( ) trimrtc RTC . ( chronyd .) RTC gains time at () (). (ppm) . +1 RTC . trimrtc trimrtc (RTC) . . . ( RTC ): 1. RTC . 2. (step) . 3. (offset) RTC ( ) . 4. RTC RTC ( rtcfile ) . writertc . trimrtc ( RTC ) chronyd . trimrtc chronyd . trimrtc rtcautotrim chronyd . writertc writertc RTC RTC ( rtcfile) . chronyd ( SIGHUP SIGINT SIGQUIT SIGTERM) trimrtc . (Other daemon commands) cyclelogs cyclelogs chronyd . . . # mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log # chronyc cyclelogs # rm /var/log/chrony/measurements1.log log . -l chronyd cyclelogs . chronyd root chronyd . dump dump chronyd dumpdir NTS NTS ntsdumpdir . chronyd . chronyd . rekey rekey chronyd keyfile . ntsdumpdir NTS . reset sources reset sources chronyd (unsynchronised) . chronyd ( ). chronyd . shutdown shutdown chronyd . SIGTERM . (Client commands) dns option dns IP chronyc . IP sources sourcestats tracking clients . . : dns -n IP . IP . dns +n IP . chronyc -n . dns -4 IPv4 . dns -6 IPv6 . dns -46 . chronyc -4 -6 . timeout timeout timeout chronyc . chronyd . retries . . retries retries retries chronyc . timeout . . keygen [id [type [bits]]] keygen ( keyfile) NTP . /dev/urandom . . ( ) key server peer . (cipher) ( SHA1 SHA1 MD5). ( ). : keygen 73 SHA1 256 SHA1 . . . AES128: keygen 151 AES128 exit, quit exit quit chronyc . help help . (SEE ALSO) chrony.conf(5), chronyd(8) (BUGS) : . (AUTHORS) chrony Richard Curnow Miroslav Lichvar . chrony 4.8 2026-04-30 CHRONYC(1)