时间同步 ntp
Posted Alex·G
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目录
1 使用ntp同步时间
1.1 如果开启了ntp服务，使用ntpsta查看同步状态
1.2 如果不使用用ntp服务，使用ntpdate -u ntp.aliyun.com 直接同步时间
echo "*/20 * * * * /usr/sbin/ntpdate -u ntp1.aliyun.com >/dev/null &" >> /var/spool/cron/root
2 时间同步ntp包相关信息
2.1 包名
# dnf -y install ntp ntpdate
-- ntp-4.2.6p5-29.el7.centos.2.x86_64 # ntp服务包
-- ntpdate-4.2.6p5-29.el7.centos.2.x86_64 # 手动同步使用包，可不安装
2.2 相关配置查看
# rpm -ql ntp-4.2.6p5-29.el7.centos.2.x86_64
/etc/dhcp/dhclient.d
/etc/dhcp/dhclient.d/ntp.sh
/etc/ntp.conf
/etc/ntp/crypto
/etc/ntp/crypto/pw
/etc/sysconfig/ntpd
/usr/bin/ntpstat
/usr/lib/systemd/ntp-units.d/60-ntpd.list
/usr/lib/systemd/system/ntpd.service
/usr/sbin/ntp-keygen
/usr/sbin/ntpd
/usr/sbin/ntpdc
/usr/sbin/ntpq
/usr/sbin/ntptime
/usr/sbin/tickadj
/usr/share/doc/ntp-4.2.6p5
...
-- # cat /etc/ntp.conf
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).
driftfile /var/lib/ntp/drift
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery
# Permit all access over the loopback interface. This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict ::1
# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 0.centos.pool.ntp.org iburst
server 1.centos.pool.ntp.org iburst
server 2.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst
#broadcast 192.168.1.255 autokey # broadcast server
#broadcastclient # broadcast client
#broadcast 224.0.1.1 autokey # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 autokey # manycast client
# Enable public key cryptography.
#crypto
includefile /etc/ntp/crypto/pw
# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys
# Specify the key identifiers which are trusted.
#trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
#requestkey 8
# Specify the key identifier to use with the ntpq utility.
#controlkey 8
# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats
# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor
2.3 使用ntp查看时间同步状态
[0 root@centos7 /root]# timedatectl set-ntp true
[0 root@centos7 /root]# timedatectl
Local time: Fri 2020-05-20 09:13:18 CST
Universal time: Fri 2020-05-20 01:13:18 UTC
RTC time: Fri 2020-05-20 01:13:16
Time zone: Asia/Shanghai (CST, +0800)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a
[0 root@centos7 /root]# ntpstat
synchronised to NTP server (162.159.200.123) at stratum 4
time correct to within 1114 ms
polling server every 64 s
[0 root@centos7 /root]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*time.cloudflare 10.40.9.201 3 u 12 64 1 293.152 14.088 1.622
time.cloudflare 10.40.9.201 3 u 11 64 1 291.438 13.657 0.763
electrode.felix 56.1.129.236 3 u 11 64 1 219.896 -10.669 1.720
ntp7.flashdance 192.36.143.153 2 u 12 64 1 253.784 -8.469 33.159
- PS
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