CHRONY.CONF(5) Configuration Files CHRONY.CONF(5) (NAME) chrony.conf - chrony (SYNOPSIS) chrony.conf (DESCRIPTION) chronyd . /etc/chrony.conf . chronyd -f . . . . . . chronyd . . . (EXAMPLES) . . : ! ; # %. . (DIRECTIVES) (Time sources) server hostname [option]... server NTP . - : . IP . chronyd online chronyc . DNS . ( ) falseticker ( ) ( maxdistance ). . ( refresh ). . IP chronyd . ( activity chronyc ). : minpoll poll . minpoll 5 . ( ) -7 (/ ) ( ) . ( ) . . maxpoll poll . maxpoll 9 ( ) . ( ) -7 (/ ) ( ) . iburst chronyd . online chronyc . burst chronyd . . key ID NTP (MAC) . MAC keyfile . key chronyd ( 2^32-1) . . ntpd ( SHA256) version . nts (NTS) . key . NTS (NTS-KE) (TLS) NTS NTP . server pool NTS-KE NTS-KE . NTP NTS-KE ( NTP NTS-KE ). NTS-KE IP Subject Alternative Name (SAN) . certset ID nts . ntstrustedcerts . 0 . maxdelay delay chronyd . . . chronyd . . ( ). maxdelay . maxdelay 0.3 . . . maxdelayratio ratio maxdelay . chronyd . . . maxdelaydevratio ratio ( ) . 10.0 . maxdelayquant p maxdelaydevratio (quantile) . p . p 0.05 0.95 . maxdelayquant 0.2 . . filter . maxdelaydevratio . mindelay delay . (jitter) maxdelayratio maxdelaydevratio . . asymmetry ratio (offset) . -0.5 +0.5 . . chronyd . offset offset ( ) . (timestamping) . -0.00005 (-50 ) . 0.0 . minsamples samples . minsamples . maxsamples samples . maxsamples . maxunreach polls ( ) . . 100000 . filter polls (median filter) NTP . . NTP . offline chronyd offline . chronyd ( online chronyc) . auto_offline ( ) . offline chronyc . ( online .) prefer prefer . noselect . (monitoring) . trust . falseticker . require ( falseticker ). trust . . xleave (interleaved mode) NTP ( RFC 9769) . ( ) . . . (state) ( clientloglimit) IP ( NAT ) . xleave presend . polltarget target chronyd minpoll maxpoll . chronyd . 8 6 60 . port port UDP NTP . ( 123 NTP ). ntsport port TCP NTS-KE nts . 4460 . presend poll chronyd ARP . ARP . presend . NTP . server: presend 9 ( ) NTP . presend xleave chronyd . minstratum stratum stratum . stratum chronyd . stratum . version version NTP . NTP . . extfield xleave . key ( SHA256) chronyd . . copy reference ID stratum . chronyd ( ) -x NTP NTP . extfield type NTPv4 . . (chronyd . ). . : F323 NTP (NTPv5) . root delay dispersion (monotonic) . chronyd . . F324 Precision Time Protocol (PTP) NTP-over-PTP (end-to-end) (one-step) . NTP-over-PTP ptpport port PTP . NTP ( hwtimestamp) . chronyd . . ipv4, ipv6 chronyd IPv4 IPv6 . -4 -6 chronyd . pool name [option]... server NTP (pool) NTP . . . server . pool : maxsources sources . chronyd . . pool: pool pool.ntp.org iburst maxsources 3 peer hostname [option]... server / NTP (peer) NTP . . NTP ( ntpd) (ephemeral) . chronyd . . server peer : iburst burst nts presend copy. xleave (interleaved mode) . key . / . (denial-of-service) key . NTP . . (man-in-the-middle) . chronyd (polling interval) . / ( server ) . initstepslew step-threshold [hostname]... ( makestep .) initstepslew chronyd (stepping) . . (slew) . chronyd . initstepslew NTP . . . chronyd . : initstepslew 30 ntp1.example.net ntp2.example.net ntp3.example.net NTP . 30 (slew) (step) . initstepslew LAN . . local initstepslew . (flywheel) . initstepslew makestep server iburst . initstepslew chronyd initstepslew . chronyd . makestep waitsync chronyc . refclock driver parameter[:option]... [option]... refclock . : . refclock . : . . chronyd : PPS (API) (PPS) . PPS ( /dev/pps?). PPS ( NTP PPS) PPS . local . : clear PPS assert ( ) . clear ( ) . : refclock PPS /dev/pps0 lock NMEA refid GPS1 refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.2 refid NMEA noselect refclock PPS /dev/pps1:clear refid GPS2 SOCK (Unix domain socket). . chronyd . refclock_sock.c chrony . SOCK gpsd . PPS 3.25 ( ) ( NMEA) PPS . gpsd chronyd gpsd(8) . gpsd chronyd . : refclock SOCK /var/run/chrony.ttyS0.sock refid GPS1 poll 2 filter 4 refclock SOCK /var/run/chrony.clk.ttyUSB0.sock refid GPS2 offset 0.2 delay 0.1 SHM NTP. 28 ntpd . SOCK . 0 1 2 3 0x4e545030 + unit . : perm=mode chronyd . . 0600 ( - ). SOCK chronyd . . chronyd root perm . chronyd . ipcs -m . SHM SOCK . : refclock SHM 0 poll 3 refid GPS1 refclock SHM 1:perm=0644 refid GPS2 PHC (PHC). PTP PTP . UTC TAI ( PTP ) UTC-TAI offset . refclock pps PHC PPS - . : nocrossts (cross timestamping) . extpps PPS PTP PPS . PPS . PTP assert clear width PPS . pin=index (pin) PPS . PHC ( ) -1 . 0 . channel=index PPS . 0 . clear clear ( ) assert ( ) PPS . . : refclock PHC /dev/ptp0 poll 0 dpoll -2 offset -37 refclock PHC /dev/ptp1:nocrossts poll 3 pps refclock PHC /dev/ptp2:extpps:pin=1 width 0.2 poll 2 RTC (RTC) . RTC . rtcfile rtcsync . : utc RTC (UTC) . : refclock RTC /dev/rtc0:utc refclock : poll poll refclock . . ( ) . chronyd . dpoll dpoll . . ( ) . refid refid refclock ASCII . refclock . refclock . lock refid refclock PPS refclock . PPS refclock . rate rate PPS ( ) . . dpoll (-3 ). . maxlockage pulses refclock lock . . . width width ( ) . PPS . PPS . (duty cycle) . pps chronyd refclock ( SHM PHC) refclock PPS . refclock ( TAI UTC). refclock . offset offset . ( ) . 0.0 . delay delay NTP ( ) . . . 1e-9 ( ) . stratum stratum (stratum) NTP refclock . refclock . . precision precision ( ) . . maxdispersion dispersion ( ). . . filter samples . . . . . PHC . prefer prefer . noselect . refclock PPS . trust . falseticker . require ( falseticker ). trust NTP . . tai UTC TAI chronyd TAI-UTC . leapsectz leapseclist . PPS . local ( TCXO OCXO ) . refclock . refclock . minsamples samples . minsamples . maxsamples samples . maxsamples . maxunreach polls ( ) . . 100000 . manual manual settime chronyc . manual settime chronyc . settime manual chronyc . ( manual settime .) acquisitionport port chronyd NTP . acquisitionport ( IPv4 IPv6) . . . 0 . NTP ( port ) NTP . acquisitionport: acquisitionport 1123 UDP 1123 . . bindacqaddress address bindacqaddress IP chronyd NTP NTS-KE (bind) . bindaddress bindcmdaddress . IPv4 IPv6 bindacqaddress . bindacqdevice interface bindacqdevice (bind) . NTP link-local IPv6 . Linux . : bindacqdevice eth0 dscp point dscp Differentiated Services Code Point (DSCP) NTP . NTP DSCP . 0 63 . ( Expedited Forwarding): dscp 46 dumpdir directory chronyd . macOS 10.12 . ( macOS 10.12 chronyd (slew) .) chronyd ( ). dumpdir chronyd dump chronyc . . -r chronyd dump . dump -r . : dumpdir /var/run/chrony IP 1.2.3.4 /var/run/chrony/1.2.3.4.dat . refid:XXXXXXXX.dat . maxsamples samples maxsamples chronyd . server refclock . 0 . 4 64 . maxsamples 1 . chronyd -q -Q . minsamples samples minsamples chronyd . server refclock . 6 . 4 64 . chronyd . tracking sourcestats ( tracking.log statistics.log) . ntsaeads ID... Authenticated Encryption with Associated Data (AEAD) NTS NTP . . (Nettle GnuTLS) . : o 15: AES-SIV-CMAC-256 o 30: AES-128-GCM-SIV 30 15 . AES-128-GCM-SIV AES-SIV-CMAC-256 NTS NTS NTP . authdata . : ntsaeads 15 NTS . ntsdumpdir directory NTS chronyd NTS-KE . NTP IP NTS-KE ( 1.2.3.4.nts) . . . : ntsdumpdir /var/lib/chrony NTS . ntsrefresh interval NTS-KE ( ) NTP . 2419200 ( ) 2^31-1 ( ) . NTP NTS NTP . ntstrustedcerts [set-ID] file|directory ( PEM) NTS-KE (CA) . set-ID 0 2^32-1 . 0 CA ( nosystemcert ). . NTS certset server pool . / . ( ) chronyd . : ntstrustedcerts /etc/pki/nts/ca1.example.net.crt ntstrustedcerts 1 /etc/pki/nts/ca2.example.net.crt ntstrustedcerts 1 /etc/pki/nts/ca3.example.net.crt ntstrustedcerts 2 /etc/pki/nts/ntp2.example.net.crt nosystemcert CA . ntstrustedcerts . nocerttimecheck limit . NTS ( RTC ) . . 0 . : nocerttimecheck 1 . refresh interval ( ) IP NTP . . ( ). 1209600 ( ) 2^31-1 ( ) . 0 . refresh . (Source selection) authselectmode mode NTP key nts (man-in-the-middle) . NTP ( maxdelay maxdistance) . ( maxdrift). NTP NTP . require trust . . chronyd root delay (dispersion) . chronyc . . noselect ( ) . : require NTP . NTP noselect . prefer . NTP NTP noselect . mix NTP . NTP NTP require trust NTP . . ignore . chronyc . chronyd 4.0 . mix: server ntp1.example.net nts server ntp2.example.net nts server ntp3.example.net refclock SOCK /var/run/chrony.ttyS0.sock ignore : authselectmode ignore server ntp1.example.net nts require trust server ntp2.example.net nts require trust server ntp3.example.net refclock /var/run/chrony.ttyS0.sock require trust combinelimit limit chronyd . . combinelimit . (limit) . . prefer . 3 . 0 . maxdistance distance maxdistance (root distance) . . (root dispersion) (root delay ) . . maxdistance . maxjitter jitter maxjitter . . . minsources sources minsources . . . ( ) . reselectdist distance chronyd . . reselectdist . . stratumweight distance stratumweight stratum chronyd . 0.001 . stratum . (System clock) clockprecision precision clockprecision ( ) . chronyd NTP NTP . . . CPU . ( Time Stamp Counter CPU) NTP . ntpdata . : clockprecision 8e-9 corrtimeratio ratio chronyd (slew) . macOS 12 . corrtimeratio ( NTP) . . corrtimeratio . . maxslewrate . tracking System time . driftfile file [interval interval] chronyd . chronyd . chronyd . ( .) driftfile chronyd . . (ppm) . 100.0 ( ). . interval . . . driftfile: driftfile /var/lib/chrony/drift fallbackdrift min-interval max-interval (Fallback drifts) . . . ( ) . : fallbackdrift 16 19 ( ) ( ) . . . `Not synchronised' . ( ) NTP . leapsecmode mode UTC . 23:59:60 . . Unix 00:00:00 UTC . 23:59:60 . UTC . leapsecmode . : system 00:00:00 UTC . 23:59:59 UTC . ( macOS 12 ). step system chronyd . system . . slew (slewing) 00:00:00 UTC 23:59:59 UTC . system step . Linux maxslewrate . ignore . . chronyd -x NTP . NTP slew smoothtime leap smear . (leap smear) . UTC . NTP . . leap smear : leapsecmode slew maxslewrate 1000 smoothtime 400 0.001024 leaponly . 1000 ppm . . 00:00:00 UTC ( . ) . 0.001024 ppm 32 ppm . leaponly leap smear leap smear . leap smear wander : duration = sqrt(4 / wander) leapsectz timezone chronyd TAI UTC . 23:59:59 23:59:60 . right/UTC . . chronyd . NTP . leap smear . TAI-UTC . leapsecmode system . . . : leapsectz right/UTC : $ TZ=right/UTC date -d 'Dec 31 2008 23:59:60' Wed Dec 31 23:59:60 UTC 2008 leapseclist file TAI-UTC NIST/IERS . leap-seconds.list . leapsectz . : leapseclist /usr/share/zoneinfo/leap-seconds.list makestep threshold limit chronyd . chronyd . chronyd (step) chronyd . . . : makestep 0.1 3 0.1 . -x chronyd . maxchange offset start ignore ( ) . (slew) . . . chronyd . . syslog . : maxchange 1000 1 2 chronyd 1000 . maxclockerror error-in-ppm maxclockerror . . 1 ppm . error-in-ppm 10 0.1 . maxdrift drift-in-ppm ( ) . chronyd . (100000 ppm Linux 500 ppm FreeBSD NetBSD macOS 10.13+ 32500 ppm illumos). 500000 ppm . maxupdateskew skew-in-ppm chronyd . . . maxupdateskew . 1000 ppm . skew-in-ppm 100 NTP 10 . . chronyd . . . maxslewrate rate-in-ppm maxslewrate chronyd (slew) . ( corrtimeratio ) chronyd ( macOS 12 ). . Linux 100000 ppm FreeBSD NetBSD macOS 10.13+ 5000 ppm illumos 32500 ppm . maxslewrate FreeBSD NetBSD macOS 10.13+ 500 ppm 5000 ppm 500 ppm . 83333.333 ppm ( ) . tempcomp file interval T0 k0 k1 k2, tempcomp file interval points-file . tempcomp . . tracking.log . . : ( ) ( ) T0 k0 k1 k2. ( ppm) : comp = k0 + (T - T0) * k1 + (T - T0)^2 * k2 -10 ppm 10 ppm . k0 . : tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 26000 0.0 0.000183 0.0 30 sysfs Linux . 26000 (26 ) . 27000 (27 ) 0.183 ppm . : ( ) . : tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 /etc/chrony.tempcomp /etc/chrony.tempcomp : 20000 1.0 21000 0.64 22000 0.36 23000 0.16 24000 0.04 25000 0.0 26000 0.04 27000 0.16 28000 0.36 29000 0.64 30000 1.0 log tempcomp tempcomp.log . NTP (NTP server) allow [all] [subnet] allow NTP NTP . NTS-KE NTS . chronyd NTP . allow chronyd . . : allow 1.2.3.4 allow 3.4.5.0/24 allow 3.4.5 allow 2001:db8::/32 allow 0/0 allow ::/0 allow IPv4 . IPv4 CIDR . . IPv6 . IPv4 IPv6 . ( IPv4 IPv6) . allow all . : allow 1.2.3.4 deny 1.2.3.0/24 allow 1.2.0.0/16 allow 1.2.3.4 deny 1.2.3.0/24 allow all 1.2.0.0/16 1.2.0.0/16 1.2.3.0/24 1.2.3.4 . allow all 1.2.0.0/16 . chronyc allow all . IPv4 IPv6 . allow deny . 1.2.3.0/28 1.2.3.0/29 1.2.3.0/25 1.2.3.0/28 . accheck chronyc . IP chronyd DNS . ( ) . initstepslew . deny [all] [subnet] allow NTP NTS-KE . . deny all allow all . bindaddress address bindaddress chronyd NTP NTS-KE . chronyd . : bindaddress 192.168.1.1 IPv4 IPv6 bindaddress NTP . binddevice interface binddevice NTP NTS-KE . . : binddevice eth0 broadcast interval address [port] broadcast chronyd NTP ( chronyd ). . . : broadcast 32 192.168.1.255 broadcast 64 192.168.2.255 12123 broadcast 64 ff02::101 UDP 123 ( NTP) . 12123 . ( 32 64) . . chronyd . NTP broadcast . chronyd NTP . NTP . ntpd allow . clientloglimit limit chronyd chronyd NTP (interleaved mode) . 524288 4096 IP NTP 4096 ( ) . 2 . 2147483648 (2 ) 16777216 . : clientloglimit 1048576 noclientlog . clients chronyc . (interleaved) NTP . local [option]... local chronyd NTP ( ) . . . local : stratum stratum (stratum) . . stratum NTP . ( GPS ) . . . distance distance root distance . chronyd root distance ( ). root distance waitunsynced . . root distance root delay root dispersion ( tracking chronyc ) : distance = delay / 2 + dispersion activate distance root distance . root distance . . 0.0 . orphan `orphan' stratum stratum . reference ID reference ID . local . local . reference ID . reference ID ( root distance distance) . orphan orphan ntpd ( tos orphan ) . waitsynced interval ( ) distance activate . distance 0 root distance . (polling) . 0 . waitunsynced interval chronyd ( ) ( ) . chronyd . orphan 0 ( ). : local stratum 5 local stratum 10 orphan distance 0.1 activate 0.5 local stratum 10 orphan distance 0.0 waitsynced 7200 waitunsynced 300 ntpsigndsocket directory ntp_signd Samba Domain Controller (DC) . chronyd MS-SNTP smbd . MS-SNTP allow allow chronyc MS-SNTP trust account brute-force . . : ntpsigndsocket /var/lib/samba/ntp_signd ntsport port TCP chronyd NTS ( NTS-KE) . . ntsservercert ntsserverkey . ntsservercert file PEM chronyd NTS . . chronyd root . . . chronyd . ntsdumpdir dumpdir -r chronyd . ntsserverkey file PEM chronyd NTS . chronyd root . . . . ntsprocesses processes chronyd NTS NTS-KE . 0 NTS-KE chronyd . 1 1000 . maxntsconnections connections NTS-KE NTS . 100 . FD_SETSIZE ( 1024). ntsaeads ID... (AEAD) NTS NTP . chronyd . (Nettle GnuTLS) . : o 15: AES-SIV-CMAC-256 o 30: AES-128-GCM-SIV 30 15 . AES-128-GCM-SIV AES-SIV-CMAC-256 NTS NTS NTP . : ntsaeads 15 NTS . NTS (RFC 8915) AES-SIV-CMAC-256 15 . AES-128-GCM-SIV chronyd chrony RFC 8915 NTS-KE . . 4.6.1 . chronyd NTS NAK . ntsdumpdir directory chronyd NTS NTS . ntskeys . chronyd NTS-KE . . : ntsdumpdir /var/lib/chrony NTS NTS . ntsntpserver hostname ( FQDN) () NTP NTS-KE . NTS-KE NTP . ntsrotate 0 . NTS-KE NTP . ntsrotate interval ( ) NTS . /dev/urandom . . chronyd . 604800 (1 ) . 2^31-1 (68 ) . ntsrotate 0 . . chronyd ntskeys rekey chronyc . NTS-KE chronyd ( ntsrotate 0 ) . NTS-KE ( ). NTS-KE ntsntpserver NTP . : ntsrotate 2592000 port port chronyd NTP . allow allow chronyc NTP (broadcast) . 123 NTP . 0 chronyd . NTP acquisitionport . ratelimit [option]... NTP . NTP . IP . IP ( NAT) . . IP clientloglimit . ratelimit ( ): interval interval . 2 . 3 (8 ) . -19 (524288 ) 12 ( 4096 ) . -4 ( burst ). burst responses (burst) interval . ( chronyd iburst). 8 . 1 255 . leak rate interval burst . . 1/2 2 . 1 4 . kod rate RATE Kiss-o'-Death (KoD) interval burst . leak . KoD RATE (polling) . . / . 0 . 0 4 . : ratelimit interval 1 burst 16 IP ( leak 2). ntsratelimit [option]... NTS-KE . ratelimit 6 ( ) kod . : ntsratelimit interval 3 burst 1 smoothtime max-freq max-wander [leaponly] smoothtime chronyd . : . . NTP falseticker . . (slewing) (stepping) makestep makestep chronyc . smoothtime reset . NTP ( ppm) ( ppm ). leaponly . leaponly leapsecmode slew . / (skew) . smoothtime activate . smoothing . ntpd : smoothtime 400 0.001 chronyd Linux : smoothtime 50000 0.01 (Command and monitoring access) bindcmdaddress address bindcmdaddress IP chronyd UDP ( chronyc) (bind) . Linux chronyd . Unix domain chronyc . root chrony . . /var/run/chrony/chronyd.sock . / . chronyd UDP 127.0.0.1 ::1 ( loopback) . localhost . : bindcmdaddress 0.0.0.0 bindcmdaddress :: . IPv4 IPv6 Unix domain bindcmdaddress . Unix domain : bindcmdaddress /var/run/chrony/chronyd.sock bindcmddevice interface bindcmddevice UDP . Linux . : bindcmddevice eth0 cmdallow [all] [subnet] allow NTP . ( << >> chronyc chronyd .) allow . cmdallow all allow all ( ). 127.0.0.1 ::1 ( loopback) . chronyd bindcmdaddress loopback . cmddeny [all] [subnet] cmdallow . . cmddeny all cmdallow all . cmdport port cmdport ( chronyc) (323) . 0 chronyd chronyc ( bindcmdaddress ) . . : cmdport 257 chronyd UDP 257 . ( chronyc -p 257 .) cmdratelimit [option]... . ratelimit localhost -4 (16 ) kod . : cmdratelimit interval 2 opencommands [command]... cmdallow . ( chronyc ): activity*, authdata, clients, manual*, ntpdata, rtcdata*, selectdata, serverstats*, smoothing*, sourcename*, sources*, sourcestats, tracking*. * . chronyc chronyd . chronyc chronyd . chronyc `Invalid command' `Bad reply from daemon' . : chronyd . . (RTC) hwclockfile file hwclockfile adjtime hwclock . chronyd UTC RTC . rtconutc . '/etc/adjtime' . : hwclockfile /etc/adjtime rtcautotrim threshold rtcautotrim RTC . chronyd RTC trimrtc chronyc . . rtcfile . : rtcautotrim 30 . rtcdevice device rtcdevice RTC . /dev/rtc . rtcfile file rtcfile RTC chronyd . : rtcfile /var/lib/chrony/rtc chronyd writertc chronyc . RTC ( ) RTC . RTC . RTC ( rtcfile -s chronyd) : 1. . 2. ( /dev/rtc ). 3. /dev/rtc . rtconutc chronyd RTC ( ). . RTC . (UTC) RTC . . rtconutc RTC UTC . -u hwclock . hwclockfile rtcsync RTC . rtcsync rtcsync RTC chronyd . rtcfile . RTC . macOS chronyd RTC . . (Logging) log [option]... log . logdir . . rawmeasurements NTP measurements.log . . . ( ) . 2016-11-09 05:40:50 203.0.113.15 N 2 111 111 1111 10 10 1.0 \ -4.966e-03 2.296e-01 1.577e-05 1.615e-01 7.446e-03 CB00717B 4B D K ( ): 1. [2015-10-13] 2. ::. - UTC . [05:40:50] 3. IP [203.0.113.15] 4. (N + - ? .) [N] 5. . [2] 6. RFC 5905 (= =) [111] 7. RFC 5905 (= =) [111] 8. maxdelay maxdelayratio maxdelaydevratio ( maxdelayquant) (= =). . [1111] 9. [10] 10. [10] 11. `' ( . ). [1.0] 12. (theta RFC 5905). . [-4.966e-03] 13. (delta RFC 5905). [2.296e-01] 14. (epsilon RFC 5905). [1.577e-05] 15. (DELTA RFC 5905). [1.615e-01] 16. (EPSILON RFC 5905). [7.446e-03] 17. . [CB00717B] 18. NTP (1= 2= 4= B= I=). [4B] 19. (D= K= H=). [D] 20. (D= K= H=). [K] measurements rawmeasurements RFC 5905 . . statistics statistics.log . ( ) . 2016-08-10 05:40:50 203.0.113.15 6.261e-03 -3.247e-03 \ 2.220e-03 1.874e-06 1.080e-06 7.8e-02 16 0 8 0.00 ( ): 1. [2015-07-22] 2. ::. - UTC . [05:40:50] 3. IP [203.0.113.15] 4. ( ). [6.261e-03] 5. ( ). [-3.247e-03] 6. ( ). [2.220e-03] 7. ( ). . [1.874e-06] 8. ( ). [1.080e-06]. 9. |old_rate - new_rate| / old_rate_error. . [7.8e-02] 10. . [16] 11. ( 0 ). [0 ] 12. (runs). . . . . [8] 13. (jitter) . -0.5 +0.5 . . [0.00 ] selection selection.log . ( ). ( ) . 2022-05-01 02:01:20 203.0.113.15 * ----- 377 1.00 \ 4.228e+01 -1.575e-04 1.239e-04 ( ): 1. [2022-05-01] 2. ::. - UTC . [02:01:20] 3. IP (reference ID) . [203.0.113.15] 4. . [*] : o N - noselect . o s - . o M - . o d - (root distance) ( maxdistance) . o ~ - (jitter) ( maxjitter) . o w - M . o S - . o O - stratum stratum ( local). o T - trust. o x - (falseticker). : o W - ( minsources require ). o P - prefer. o U - ( ). o D - root distance ( ) ( combinelimit). : o + - . o * - ( root delay root dispersion). 5. . ( authselectmode) . [-----] o N noselect . o P prefer . o T trust . o R require . 6. (). . 377 . [377] 7. *. root distance . 1 * . 10 1 . [1.00] 8. . [4.228e+01] 9. root distance . [-1.575e-04] 10. root distance . [1.239e-04] tracking slew tracking.log . ( ) . 2017-08-22 13:22:36 203.0.113.15 2 -3.541 0.075 -8.621e-06 N \ 2 2.940e-03 -2.084e-04 1.534e-02 3.472e-04 8.304e-03 ( ): 1. [2017-08-22] 2. ::. - UTC . [13:22:36] 3. IP . [203.0.113.15] 4. stratum . [2] 5. ( ppm UTC ). [-3.541] 6. ( ppm). [0.075] 7. slew ( UTC ). [-8.621e-06] 8. (N + - ? .) [N] 9. . [2] 10. ( ). [2.940e-03] 11. ( UTC ). [-2.084e-04] 12. ( ). [1.534e-02] 13. ( ). [3.472e-04] 14. ( ). root delay . [8.304e-03] rtc (RTC) . ( ) rtc.log . 2015-07-22 05:40:50 -0.037360 1 -0.037434\ -37.948 12 5 120 ( ): 1. [2015-07-22] 2. ::. - UTC . [05:40:50] 3. RTC . RTC [-0.037360]. 4. . ( ). [1] 5. . . [-0.037434] 6. RTC . ppm RTC . [-37.948] 7. . [12] 8. . . [5] 9. ( ). [120] refclocks refclocks.log . ( ) . 2009-11-30 14:33:27.000000 PPS2 7 N 1 4.900000e-07 -6.741777e-07 1.000e-06 ( ): 1. [2009-11-30] 2. ::.. - UTC . [14:33:27.000000] 3. (Reference ID) . [PPS2] 4. poll poll - . [7] 5. (N + - ). [N] 6. PPS ( - ). [1] 7. - . [4.900000e-07] 8. . . [-6.741777e-07] 9. (dispersion) . [1.000e-06] tempcomp tempcomp.log . ( ) . 2015-04-19 10:39:48 2.8000e+04 3.6600e-01 ( ): 1. [2015-04-19] 2. ::. - UTC . [10:39:48] 3. . [2.8000e+04] 4. ppm . [3.6600e-01] : log measurements statistics tracking logbanner entries () log . logbanner . . logchange threshold syslog . NTP settime chronyc . . : logchange 0.1 . syslog . logdir directory log . . : logdir /var/log/chrony mailonchange email threshold chronyd . : mailonchange root@localhost 0.5 . root . -F chronyd (fork) sendmail . (Miscellaneous) confdir directory... confdir .conf (include) . . ( ) confdir . . . . : confdir /etc/chrony.d sourcedir directory... sourcedir confdir .sources NTP ( server pool peer) reload sources chronyc . NTP DHCP . . : sourcedir /var/run/chrony-dhcp include pattern include (wildcard) . confdir . . : include /etc/chrony.d/*.conf hwtimestamp interface [option]... (HW timestamping) NTP . (NIC) . (offset) . NTP ( ) HW timestamping . interleaved xleave server peer . Linux 3.19 . (NIC) HW timestamping ethtool -T . hardware-raw-clock hardware-transmit hardware-receive . all ntp NTP . bridged bonded Linux 4.13 . HW timestamping chronyd . - . chronyd NIC . . chronyd HW timestamping . HW timestamping ( PTP) /sys/class/ptp/ptpX/n_vclocks . Linux 5.14 . . ( ) measurements.log ( log) ntpdata . serverstats . HW timestamping . * chronyd HW timestamping . hwtimestamp : minpoll poll NIC . . NTP NTP . 0 ( ) -6 (/ ) 20 ( ) . maxpoll poll NIC . minpoll + 1 0 minpoll 1 ( ) . minpoll . minsamples samples NIC . 2 . maxsamples samples NIC . 16 . precision precision NIC . 100e-9 ( ) . txcomp compensation . NIC . 0 . rxcomp compensation . NIC . 0 . nocrossts NIC (cross- timestamp) . . rxfilter filter . filter : all . ntp NTP . ptp PTP . none . NTP (NIC) . NIC PTP . none . PTP NTP-over-PTP ptpport PTP . all NIC all ntp NTP PTP NTP UDP . : hwtimestamp eth0 hwtimestamp eth1 txcomp 300e-9 rxcomp 645e-9 hwtimestamp * hwtstimeout timeout NTP NIC () NTP . chronyd . (NIC ). chronyd . . 0.001 . measurements.log ntpdata interleaved ( ) 0.01 . NTP . keyfile file NTP NTP (MAC) . : keyfile /etc/chrony.keys - . : 10 tulip 11 hyacinth 20 MD5 ASCII:crocus 25 SHA1 HEX:933F62BE1D604E68A81B557F18CFA200483F5B70 30 AES128 HEX:7EA62AE64D190114D46D5A082F948EC1 31 AES256 HEX:37DDCBC67BB902BCB8E995977FAB4D2B5642F5B32EBCEEE421921D97E5CBFE39 ... . 2^32-1 . MAC . MD5 . chronyd (Nettle GnuTLS NSS LibTomCrypt) : MD5 SHA1 SHA256 SHA384 SHA512. chronyd : SHA3-224 SHA3-256 SHA3-384 SHA3-512 TIGER WHIRLPOOL AES128 AES256. ASCII ASCII: HEX: . 2047 . ( AES128 AES256). ( HEX: ). chronyd syslog . AES SHA3 . MD5 . MD5 MAC NTP NTP MAC . extfield ( ) NTP MD5 . keygen chronyc . MD5 SHA1 . root chronyd ( chronyd rekey chronyc ). lock_all lock_all chronyd RAM (page out) . . Linux FreeBSD NetBSD illumos . pidfile file chronyd -Q (PID) chronyd . /run/chrony/chronyd.pid . pidfile : pidfile /run/chronyd.pid / PID . ptpport port ptpport chronyd NTP PTP (NTP-over-PTP) NIC NTP PTP PTP . NIC PTP 319 ( PTP) . 0 () . NTP-over-PTP . . . PTP chronyd . NTP . NTP NTP-over-PTP port PTP . NIC PTP rxfilter hwtimestamp ptp . F324 PTP . : server ntp1.example.net minpoll 0 maxpoll 0 xleave port 319 extfield F324 hwtimestamp * rxfilter ptp ptpport 319 ptpdomain domain ptpdomain PTP NTP-over-PTP . . 123 0 255 . sched_priority priority Linux FreeBSD NetBSD illumos sched_priority SCHED_FIFO ( ). macOS () . macOS pthread_setschedparam() (SCHED_FIFO) chronyd . chronyd . chronyd chronyd . . pthread_setschedparam(3) . macOS thread_policy_set() . . user user user chronyd root . Linux chronyd libcap . macOS FreeBSD NetBSD illumos chronyd (fork) . root . chrony . (EXAMPLES) NTP NTP chronyd ( NTP ) . NTP . : o . . o ISP NTP . o NTP stratum 1 stratum 2 . . . o pool.ntp.org NTP ntp1.example.net ntp2.example.net ntp3.example.net chrony.conf : server ntp1.example.net server ntp2.example.net server ntp3.example.net . driftfile makestep rtcsync . iburst server . : server ntp1.example.net iburst server ntp2.example.net iburst server ntp3.example.net iburst driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync (pool) NTP ( ) server pool . : pool pool.ntp.org iburst driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync ( pool) (NTS) chronyd NTS nts . : server ntp1.example.net iburst nts server ntp2.example.net iburst nts server ntp3.example.net iburst nts driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync NTP NTP chronyd NTP . chronyd . . NTP ntp1.example.net ntp2.example.net ntp3.example.net chrony.conf : server ntp1.example.net offline server ntp2.example.net offline server ntp3.example.net offline driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync offline chronyd chronyc . chronyd online offline chronyc . pppd chronyc /usr/bin/chronyc /etc/ppp/ip-up : /usr/bin/chronyc online /etc/ppp/ip-down : /usr/bin/chronyc offline chronyd . (Isolated networks) chronyd . . . local chronyd . . chronyd manual settime chronyc . chronyd . . << >> . smoothtime settime . smoothtime activate . . ( ntp.local) ( 192.168.165.x ): initstepslew 1 client1 client3 client6 driftfile /var/lib/chrony/drift local stratum 8 manual allow 192.168.165.0/24 smoothtime 400 0.01 rtcsync : server ntp.local iburst driftfile /var/lib/chrony/drift allow 192.168.165.0/24 makestep 1.0 3 rtcsync allow . orphan local . local . ( IP ) . . ( ntp1.local ntp2.local ntp3.local): initstepslew 1 ntp2.local ntp3.local server ntp2.local server ntp3.local driftfile /var/lib/chrony/drift local stratum 8 orphan manual allow 192.168.165.0/24 rtcsync initstepslew server . . RTC (RTC tracking) <<>> . chronyd RTC . . RTC ( ). 2.6 HPET HPET_EMULATE_RTC . chronyd RTC . chronyd NTP . . . chronyd RTC ( /dev/rtc ) . RTC RTC RTC . NTP RTC ( rtcfile ). dump writertc chronyc . chronyd RTC RTC . . . . RTC . chronyd . ( RTC trimrtc chronyc . trimrtc RTC ). dump writertc offline chronyd chronyd . ( ). chronyd RTC . log rtc . . chrony.conf . server ntp1.example.net maxdelay 0.4 offline server ntp2.example.net maxdelay 0.4 offline server ntp3.example.net maxdelay 0.4 offline logdir /var/log/chrony log statistics measurements tracking driftfile /var/lib/chrony/drift makestep 1.0 3 maxupdateskew 100.0 dumpdir /var/lib/chrony rtcfile /var/lib/chrony/rtc pppd . /etc/ppp/ip-up /etc/ppp/ip-down . /etc/ppp/ip-up: /usr/bin/chronyc online /etc/ppp/ip-down: /usr/bin/chronyc -m offline dump writertc chronyd -r -s . chronyd . chronyd SIGKILL SIGTERM SIGTERM RTC . NTP (Public NTP server) chronyd NTP pool.ntp.org NTP . ( pool NTP). ( GPS) refclock . interleaved ratelimit . right/UTC UTC . -r dumpdir chronyd ( ) . : server ntp1.example.net iburst server ntp2.example.net iburst server ntp3.example.net iburst server ntp4.example.net iburst makestep 1.0 3 rtcsync allow clientloglimit 100000000 leapsectz right/UTC driftfile /var/lib/chrony/drift dumpdir /var/run/chrony (SEE ALSO) chronyc(1), chronyd(8) (BUGS) : . (AUTHORS) chrony Richard Curnow Miroslav Lichvar . chrony 4.8 2026-04-30 CHRONY.CONF(5)