配置ntp

一 . 内网NTP-Server（192.168.1.12）

备份配置文件

cp /etc/ntp.conf /etc/ntp.conf.bak

改配置文件

vim /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.
# 允许网段访问

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).

# 注释掉
# 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

# 下面2行， 以本地时间作为时间服务
server 127.127.1.0 

fudge 127.127.1.0 stratum 10

start启动服务，enable 开机启动， status查看状态。

systemctl start ntpd.service
systemctl enable ntpd.service
systemctl status ntpd.service

查看ntpd端口情况

[root@node1 ~]# ss -tlunp |grep ntp
udp    UNCONN     0      0      192.168.1.12:123                   *:*                   users:(("ntpd",pid=114741,fd=19))
udp    UNCONN     0      0      127.0.0.1:123                   *:*                   users:(("ntpd",pid=114741,fd=18))
udp    UNCONN     0      0         *:123                   *:*                   users:(("ntpd",pid=114741,fd=16))
udp    UNCONN     0      0      fe80::8c4a:435d:d7ec:6826%ens33:123                  :::*                   users:(("ntpd",pid=114741,fd=21))
udp    UNCONN     0      0       ::1:123                  :::*                   users:(("ntpd",pid=114741,fd=20))
udp    UNCONN     0      0        :::123                  :::*                   users:(("ntpd",pid=114741,fd=17))

ntpq -p 查看网络中的NTP服务器，同时显示客户端和每个服务器的关系

# ntpq -p

改时间

date -s 18:00:00

二 . 内网NTP-Clients（192.168.1.13）

备份配置文件

cp /etc/ntp.conf /etc/ntp.conf.bak

改配置文件

vim /etc/ntp.conf  

#改成相对应的服务器，把下面的注释掉

server 192.168.1.12 iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst

多台ntp的情况

客户端配置
driftfile /var/lib/ntp/drift
server 192.168.8.102 prefer
server 192.168.8.101
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys

start启动服务，enable 开机启动， status查看状态。

systemctl start ntpd.service
systemctl enable ntpd.service
systemctl status ntpd.service

查看时间

date

查看网络中的NTP服务器

ntpq -p

[root@node2 /etc]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*node1           LOCAL(0)        11 u   62   64   77    2.050   -2.689   2.395