Linux离线安装NTP服务，无外网环境下配置本地时间同步_linux服务器时间校正 无网

1、常用命令

rpm -qa | grep ntp #查询已安装的ntp版本信息等

rpm -e --nodeps ntp-4.2.6p5-29.el7.centos.2.x86_64 #卸载

systemctl status ntpd #查询ntp服务状态

systemctl start ntpd #启动

systemctl stop ntpd #停止

systemctl restart ntpd #重启

ntpq -p #查看ntp服务器与上层ntp的状态

ntpstat #查看时间同步状态(查看ntp服务器有无和上层ntp连通)，这个一般需要5-10分钟后才能成功连接和同步。所以，服务器启动后需要稍等下。

2、下载ntp的安装包：

链接：https://pan.baidu.com/s/15yJV9A9zn2KBvy08A080Kw
提取码：cdjz

ntp:可以为其配置ntp.conf将其设置为自动同步某服务器时钟。

3、安装命令：

rpm -ivh ntp-4.2.6p5-29.el7.centos.2.x86_64.rpm

安装说明：

直接安装ntp-4.2.6p5-29.el7.centos.2.x86_64.rpm如果不提示缺少依赖就不用再安装另外两个了。
如果提示缺少安装相应的rpm包，也是rpm -ivh …

4、配置：

三台虚拟机：

# 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
restrict 192.168.79.2 mask 255.255.255.0 nomodify notrap #集群所在网段的网关（Gateway），子网掩码（Genmask）

# 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
server 127.0.0.1
fudge 127.0.0.1 stratum 10

#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
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修改完成后保存退出，并重启ntp（systemctl restart ntpd）。

设置ntp客户端（以worker1为例，其余相同，略）

编辑配置文件（vim /etc/ntp.conf），注释掉默认ntp服务，使用我们自己配置的ntp服务器（即 192.168.79.100），具体修改部分突出显示，如下：

【！！！】这里需要注意的是，在使用ntp服务器时，如果有防火墙，则需要开启ntp服务器的udp协议123端口，否则其他虚拟机不能成功同步时间。

# 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

restrict 192.168.79.100 nomodify notrap noquery

# 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
server 192.168.79.100
Fudge 192.168.79.100 stratum 10

#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
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修改完成后保存退出并重启ntp（systemctl restart ntpd）。

5、查看状态：

1）启动ntp服务

systemctl start ntpd
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2）查看ntp服务器有无和上层ntp连通

ntpstat
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3）查看ntp服务器与上层ntp的状态

ntpq -p
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6、设置开机自启动：

systemctl enable ntpd.service
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查看从ntp服务状态可能会有如下错误
inappropriate address 192.168.79.100 for the fudge command, line ignored
经测试改了fudge的首字母为F就可以修复上述错误，看网上也都是小写的，很奇怪。
几分钟后查看主从ntp主机的时间就同步了，同步较慢稍等即可。

参考文章：
https://blog.csdn.net/qq_29171935/article/details/87916664
https://blog.csdn.net/qq_38591756/article/details/85243965
https://blog.51cto.com/13670314/2409692