| 知乎专栏 |
目录
默认域名服务器无法解析外部域名
[root@production ~]# ping www.netkiller.cn ping: www.netkiller.cn: Name or service not known
100.79.1.250 内部域名服务器
[root@production ~]# cat /etc/resolv.conf # Generated by NetworkManager search openstacklocal nameserver 100.79.1.250 options timeout:1 single-request-reopen
添加域名服务器
[root@production ~]# echo "nameserver 8.8.8.8" >> /etc/resolv.conf [root@production ~]# cat /etc/resolv.conf # Generated by NetworkManager search openstacklocal nameserver 100.79.1.250 options timeout:1 single-request-reopen nameserver 8.8.8.8
测试域名解析是否正常
[root@production ~]# ping www.netkiller.cn PING netkiller.github.io (185.199.111.153) 56(84) bytes of data. ^C64 bytes from 185.199.111.153: icmp_seq=4 ttl=48 time=124 ms --- netkiller.github.io ping statistics --- 4 packets transmitted, 1 received, 75% packet loss, time 3058ms rtt min/avg/max/mdev = 124.042/124.042/124.042/0.000 ms
管理员常用工具
dnf install -y bzip2 tree psmisc \ telnet wget rsync vim-enhanced \ net-tools bind-utils
故障描述，今日服务器，突然有个功能不能用了，经过艰辛排查发现是时间戳计算出错。服务器时间比本地时间快了6分钟
neo@Mac-mini-M4 ~/netkiller (master)> date 2024年11月13日 星期三 10时32分52秒 CST
服务器时间快了6分钟
[root@testing ~]# date Wed Nov 13 10:38:59 AM CST 2024
检查时间同步进程 chronyd 正常
[root@testing ~]# systemctl status chronyd
● chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; preset: enabled)
Active: active (running) since Wed 2024-10-02 08:34:26 CST; 1 month 11 days ago
Docs: man:chronyd(8)
man:chrony.conf(5)
Main PID: 690 (chronyd)
Tasks: 1 (limit: 100479)
Memory: 3.3M
CPU: 543ms
CGroup: /system.slice/chronyd.service
└─690 /usr/sbin/chronyd -F 2
查看配置文件，发现少了 pool 配置
[root@testing ~]# cat /etc/chrony. chrony.conf chrony.keys [root@testing ~]# cat /etc/chrony.conf server ntp.myhuaweicloud.com minpoll 4 maxpoll 10 iburst # Ignore stratum in source selection. stratumweight 0.05 # Record the rate at which the system clock gains/losses time. driftfile /var/lib/chrony/drift # Enable kernel RTC synchronization. rtcsync # In first three updates step the system clock instead of slew # if the adjustment is larger than 10 seconds. makestep 10 3 # Allow NTP client access from local network. #allow 192.168/16 # Listen for commands only on localhost. bindcmdaddress 127.0.0.1 bindcmdaddress ::1 # Serve time even if not synchronized to any NTP server. #local stratum 10 # Disable logging of client accesses. noclientlog # Send a message to syslog if a clock adjustment is larger than 0.5 seconds. logchange 0.5 logdir /var/log/chrony #log measurements statistics tracking
检查时间同步服务器源，返回空数据
[root@testing ~]# chronyc sources MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== [root@testing ~]# chronyc sources -v .-- Source mode '^' = server, '=' = peer, '#' = local clock. / .- Source state '*' = current best, '+' = combined, '-' = not combined, | / 'x' = may be in error, '~' = too variable, '?' = unusable. || .- xxxx [ yyyy ] +/- zzzz || Reachability register (octal) -. | xxxx = adjusted offset, || Log2(Polling interval) --. | | yyyy = measured offset, || \ | | zzzz = estimated error. || | | \ MS Name/IP address Stratum Poll Reach LastRx Last sample ===============================================================================
检查时间同步状态，返回空数据
[root@testing ~]# chronyc sourcestats -v
.- Number of sample points in measurement set.
/ .- Number of residual runs with same sign.
| / .- Length of measurement set (time).
| | / .- Est. clock freq error (ppm).
| | | / .- Est. error in freq.
| | | | / .- Est. offset.
| | | | | | On the -.
| | | | | | samples. \
| | | | | | |
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
检查NTP设置，正常
[root@testing ~]# timedatectl show
Timezone=Asia/Shanghai
LocalRTC=no
CanNTP=yes
NTP=yes
NTPSynchronized=no
TimeUSec=Wed 2024-11-13 10:43:38 CST
RTCTimeUSec=Wed 2024-11-13 10:37:22 CST
[root@testing ~]# timedatectl status
Local time: Wed 2024-11-13 10:43:56 CST
Universal time: Wed 2024-11-13 02:43:56 UTC
RTC time: Wed 2024-11-13 02:37:40
Time zone: Asia/Shanghai (CST, +0800)
System clock synchronized: no
NTP service: active
RTC in local TZ: no
如果 NTP=no 使用下面命令开启 NTP
timedatectl set-ntp yes
解决方案，添加 pool 配置到
[root@testing ~]# cat /etc/chrony.conf server ntp.myhuaweicloud.com minpoll 4 maxpoll 10 iburst # Ignore stratum in source selection. stratumweight 0.05 # Record the rate at which the system clock gains/losses time. driftfile /var/lib/chrony/drift # Enable kernel RTC synchronization. rtcsync # In first three updates step the system clock instead of slew # if the adjustment is larger than 10 seconds. makestep 10 3 # Allow NTP client access from local network. #allow 192.168/16 # Listen for commands only on localhost. bindcmdaddress 127.0.0.1 bindcmdaddress ::1 # Serve time even if not synchronized to any NTP server. #local stratum 10 # Disable logging of client accesses. noclientlog # Send a message to syslog if a clock adjustment is larger than 0.5 seconds. logchange 0.5 logdir /var/log/chrony #log measurements statistics tracking pool ntp1.aliyun.com iburst pool ntp.tencent.com iburst pool ntp1.bce.baidu.com iburst
重启 chronyd 服务
[root@testing ~]# systemctl restart chronyd
[root@testing ~]# systemctl status chronyd
● chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; preset: enabled)
Active: active (running) since Wed 2024-11-13 10:55:09 CST; 19s left
Docs: man:chronyd(8)
man:chrony.conf(5)
Process: 392965 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 392968 (chronyd)
Tasks: 1 (limit: 100479)
Memory: 1.3M
CPU: 58ms
CGroup: /system.slice/chronyd.service
└─392968 /usr/sbin/chronyd -F 2
Nov 13 10:55:09 testing chronyd[392968]: chronyd version 4.5 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 +DEBUG)
Nov 13 10:55:09 testing chronyd[392968]: Frequency 0.000 +/- 1000000.000 ppm read from /var/lib/chrony/drift
Nov 13 10:55:09 testing chronyd[392968]: Loaded seccomp filter (level 2)
Nov 13 10:55:09 testing systemd[1]: Started NTP client/server.
Nov 13 10:55:20 testing chronyd[392968]: Selected source 106.55.184.199 (ntp.tencent.com)
Nov 13 10:55:20 testing chronyd[392968]: System clock wrong by -375.557443 seconds
Nov 13 10:49:04 testing chronyd[392968]: System clock was stepped by -375.557443 seconds
Nov 13 10:49:06 testing chronyd[392968]: Selected source 120.25.115.20 (ntp1.aliyun.com)
Nov 13 10:51:18 testing chronyd[392968]: Selected source 106.55.184.199 (ntp.tencent.com)
Nov 13 10:54:31 testing chronyd[392968]: Selected source 120.25.115.20 (ntp1.aliyun.com)
再次查看 pool 服务器
[root@testing ~]# chronyc sources
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^? 120.25.115.20 0 6 0 - +0ns[ +0ns] +/- 0ns
^? 106.55.184.199 2 6 1 0 +375.6s[+375.6s] +/- 22ms
[root@testing ~]# chronyc sources -v
.-- Source mode '^' = server, '=' = peer, '#' = local clock.
/ .- Source state '*' = current best, '+' = combined, '-' = not combined,
| / 'x' = may be in error, '~' = too variable, '?' = unusable.
|| .- xxxx [ yyyy ] +/- zzzz
|| Reachability register (octal) -. | xxxx = adjusted offset,
|| Log2(Polling interval) --. | | yyyy = measured offset,
|| \ | | zzzz = estimated error.
|| | | \
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^* 120.25.115.20 2 6 245 71 -326us[ -776us] +/- 5099us
^- 106.55.184.199 2 6 173 10 +1630us[+1630us] +/- 29ms
[root@testing ~]# chronyc sourcestats -v
.- Number of sample points in measurement set.
/ .- Number of residual runs with same sign.
| / .- Length of measurement set (time).
| | / .- Est. clock freq error (ppm).
| | | / .- Est. error in freq.
| | | | / .- Est. offset.
| | | | | | On the -.
| | | | | | samples. \
| | | | | | |
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
120.25.115.20 6 6 334 -0.085 13.288 -7613ns 401us
106.55.184.199 9 4 396 +16.456 38.482 +2761us 2680us
有服务器返回，正常
[root@testing ~]# chronyc tracking Reference ID : 78197314 (120.25.115.20) Stratum : 3 Ref time (UTC) : Wed Nov 13 02:54:34 2024 System time : 0.000003450 seconds fast of NTP time Last offset : -0.000449605 seconds RMS offset : 0.011590191 seconds Frequency : 101.751 ppm fast Residual freq : -0.085 ppm Skew : 14.673 ppm Root delay : 0.008122038 seconds Root dispersion : 0.003573609 seconds Update interval : 3.0 seconds Leap status : Normal
Leap status : Normal 状态正常
[root@testing ~]# timedatectl show Timezone=Asia/Shanghai LocalRTC=no CanNTP=yes NTP=yes NTPSynchronized=yes TimeUSec=Wed 2024-11-13 10:57:21 CST RTCTimeUSec=Wed 2024-11-13 10:57:21 CST
NTPSynchronized=yes 表示同步成功
现在，查看时间，同步正常，问题彻底解决。