linux 培训-基础篇

发布时间：2020-08-10 19:05:26 作者：wwjfeng
来源：ITPUB博客阅读：217

一.systemctl

1.服务器启动过程

redhat 7以前启动方式，init: 按顺序启动 1 2 3 4。启动慢

redhat 7 systemd：并行化启动按依赖关系启动。 1 2 3 4（network） 5 6 7 依赖于4则直接不启动。启动快

运行等级

init 0 关机

1 单用户模式

2 无网络模式

3 无图形化模式

4 用户自定义模式

5 GUI

6 reboot

2.systemctl 使用说明

-启动服务

old: service xxxx start

new: systemctl start xxx.service

systemctl restart xxx.service 服务会瞬断

systemctl reload xxx.service 服务不会中断

-设置开机启动

old：chkconfig xxx on

new：systemctl enable xxx.service

-显示当前的运行等级

# systemctl get-default

graphical.target

切换运行等级

systemctl isolate multi-user.target/emergency.target/graphical.target

-总结

linux 培训-基础篇

二. SSH

1.SSH概念

shell 每一个用户都有一个自己的壳包含权限，个性化设置，环境变量等

用户需要通过shell 才能跟内核交互

SSH 就是secure Shell

用户必须要通过shell来与os内核交互

user

-----

shell

-----

kernel

-----

hardware

2.SSH种类

(1).ssh user@ip

不信任方式，服务器将自己的公钥给客户端

(2).配置基于秘钥/公钥的身份验证方式

加密方式：

-对称加密 same key

-非对称加密公钥加密，私钥解密

信任的方式：客户端将自己的公钥发送给服务器，客户端的公钥是受信任的则不需要密码

(3).配置过程

linux

-ssh-keygens

生成客户端自己的公钥和私钥

-ssh-copy-id -i 指定公钥 user/hostname --将客户端公钥上传给服务器端

将客户端公钥上传至服务器端

windows

-secureCRT 在客户端生成公钥/秘钥

tool -> create public key

-将公钥上传到目标服务器，cat 公钥 >> ~/.ssh/authorized_keys

3.自定义SSH服务配置

vi /etc/ssh/sshd_config

#LoginGraceTime 2m。 --2分钟不操作断开ssh连接

#PermitRootLogin yes --是否允许root登陆

#StrictModes yes

#MaxAuthTries 6 --允许尝试登陆的次数

#MaxSessions 10

#PasswordAuthentication yes --允许密码登陆

三.Linux日志系统

1.常规系统日志结构

cd /var/log

messages --通用日志

secure --和安全及身份验证相关

maillog --和邮件相关

cron --计划任务相关

boot.log --系统启动log

2.常规日志服务配置

(1).日志配置文件

vim /etc/rsyslog.conf

*.info;mail.none;authpriv.none;cron.none /var/log/messages

*.info 所有类别的info等级以上的日志记录在messages中。

mail.none mail 类别的日志不记录

mail.* -/var/log/maillog 异步

(2).日志优先集

linux 培训-基础篇

3.分析一个日志条目

linux 培训-基础篇

4.系统审查日志systemd journal

(1)

systemd journal 默认情况下存储在/run/log，系统重新启动后内容会被清除。要求转换角色为rootq进行查看。

-a 所有

-n 5 最后5行

-p 优先级（err，info）

-b 启动消息

-f 监控

--since “2014-02-10 20:30:00” --until “2014-02-10 21:30:00” 指定范围

--since today 显示今天

-o 更改日志的输出模式

(2).常用命令

# journalctl --priority err

# journalctl _UID=1000 -n 5

# journalctl --since 13:00:00 --until 14:00:00 _SYSTEMD_UNIT="sshd.service"

(3).永久保存journal日志

[root@rh2 ~]# mkdir -p /var/log/journal

[root@rh2 ~]# chown root:systemd-journal /var/log/journal

[root@rh2 ~]# chmod 2755 /var/log/journal

[root@rh2 ~]# systemctl restart systemd-journald.service

日志将永久保存在/var/log/journal

四.时间

1.时间命令

# timedatectl

Local time: Mon 2018-07-30 14:22:32 CST

Universal time: Mon 2018-07-30 06:22:32 UTC

RTC time: Mon 2018-07-30 06:22:32

Time zone: Asia/Shanghai (CST, +0800)

NTP enabled: no

NTP synchronized: yes

RTC in local TZ: no

DST active: n/a

timedatectl set-time 15:00:00 设置本地时间

2.ntp

(1).安装包chrony.x86_64

yum -install -y chrony.x86_64

(2).开启ntp服务器支持

timedatectl set-ntp true

(3).配置ntp服务器

vi /etc/chrony.conf
server ntp1.aliyun.com iburst
server ntp2.aliyun.com iburst
server ntp3.aliyun.com iburst

(4).重启服务

systemctl restart chronyd
systemctl enable chronyd
# timedatectl
      Local time: Mon 2018-07-30 14:49:16 CST
  Universal time: Mon 2018-07-30 06:49:16 UTC
        RTC time: Mon 2018-07-30 06:49:16
       Time zone: Asia/Shanghai (CST, +0800)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: n/a

(5).查看ntp时间状态

# chronyc sources -v
210 Number of sources = 2
  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current synced, '+' = combined , '-' = not combined,
| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.
||                                                 .- 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  10   377   643  +4362us[+4362us] +/-   50ms
^* 203.107.6.88                  2  10   377   704    -27ms[  -29ms] +/-   68ms

五.网络

1.常规网络配置

RHEL6 ： network service network restart 管理的是设备名 ifcfg-设备名

RHEL7 ： NetworkManager --> nmcli 管理的是连接名 ifcfg-连接名

相关服务：systemctl start NetworkManager

网卡的配置文件： /etc/sysconfig/network-scripts/ifcfg-xxxx

2.nmcli

(1).显示链接名和设备名

# nmcli connection show 
NAME       UUID                                  TYPE            DEVICE 
Profile 1  105c22e6-d4be-4a1b-978d-a53b81b60d33  802-3-ethernet  ens38  
ens33      e11de05d-64d8-421e-97f5-bd9cfbc9f647  802-3-ethernet  ens33  
virbr0     3728e459-2ed5-405b-8f2c-f56c9c22a16d  bridge          virbr0 
eth0       bd139d4f-d603-47a1-8ee6-95f883cddcf2  802-3-ethernet  --

(2).查看连接名信息

# nmcli connection show Profile\ 1
connection.id:                          Profile 1
connection.uuid:                        105c22e6-d4be-4a1b-978d-a53b81b60d33
connection.stable-id:                   --
connection.interface-name:              --
connection.type:                        802-3-ethernet
connection.autoconnect:                 yes
connection.autoconnect-priority:        0
connection.autoconnect-retries:         -1 (default)
connection.timestamp:                   1532948503
connection.read-only:                   no
connection.permissions:                 --
connection.zone:                        --
connection.master:                      --
connection.slave-type:                  --
connection.autoconnect-slaves:          -1 (default)
connection.secondaries:                 --
connection.gateway-ping-timeout:        0
connection.metered:                     unknown
connection.lldp:                        -1 (default)
802-3-ethernet.port:                    --
802-3-ethernet.speed:                   0
802-3-ethernet.duplex:                  --
802-3-ethernet.auto-negotiate:          no
802-3-ethernet.mac-address:             --
802-3-ethernet.cloned-mac-address:      --
802-3-ethernet.generate-mac-address-mask:--
802-3-ethernet.mac-address-blacklist:   --
802-3-ethernet.mtu:                     auto
802-3-ethernet.s390-subchannels:        --
802-3-ethernet.s390-nettype:            --
802-3-ethernet.s390-options:            --
802-3-ethernet.wake-on-lan:             1 (default)
802-3-ethernet.wake-on-lan-password:    --
ipv4.method:                            manual
ipv4.dns:                               114.114.114.114
ipv4.dns-search:                        --
ipv4.dns-options:                       (default)
ipv4.dns-priority:                      0
ipv4.addresses:                         192.168.1.100/24, 1.1.1.1/8
ipv4.gateway:                           192.168.1.1
ipv4.routes:                            --
ipv4.route-metric:                      -1
ipv4.ignore-auto-routes:                no
ipv4.ignore-auto-dns:                   no
ipv4.dhcp-client-id:                    --
ipv4.dhcp-timeout:                      0
ipv4.dhcp-send-hostname:                yes
ipv4.dhcp-hostname:                     --
ipv4.dhcp-fqdn:                         --
ipv4.never-default:                     no
ipv4.may-fail:                          yes
ipv4.dad-timeout:                       -1 (default)
ipv6.method:                            auto
ipv6.dns:                               --
ipv6.dns-search:                        --
ipv6.dns-options:                       (default)
ipv6.dns-priority:                      0
ipv6.addresses:                         --
ipv6.gateway:                           --
ipv6.routes:                            --
ipv6.route-metric:                      -1
ipv6.ignore-auto-routes:                no
ipv6.ignore-auto-dns:                   no
ipv6.never-default:                     no
ipv6.may-fail:                          yes
ipv6.ip6-privacy:                       -1 (unknown)
ipv6.addr-gen-mode:                     stable-privacy
ipv6.dhcp-send-hostname:                yes
ipv6.dhcp-hostname:                     --
ipv6.token:                             --
proxy.method:                           none
proxy.browser-only:                     no
proxy.pac-url:                          --
proxy.pac-script:                       --
GENERAL.NAME:                           Profile 1
GENERAL.UUID:                           105c22e6-d4be-4a1b-978d-a53b81b60d33
GENERAL.DEVICES:                        ens38
GENERAL.STATE:                          activated
GENERAL.DEFAULT:                        no
GENERAL.DEFAULT6:                       no
GENERAL.VPN:                            no
GENERAL.ZONE:                           --
GENERAL.DBUS-PATH:                      /org/freedesktop/NetworkManager/ActiveConnection/224
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/Settings/2
GENERAL.SPEC-OBJECT:                    --
GENERAL.MASTER-PATH:                    --
IP4.ADDRESS[1]:                         1.1.1.1/8
IP4.ADDRESS[2]:                         192.168.1.100/24
IP4.GATEWAY:                            192.168.1.1
IP4.DNS[1]:                             114.114.114.114
IP6.ADDRESS[1]:                         fe80::f434:5dd6:8419:fc87/64
IP6.GATEWAY:                            --

(3).创建网络连接

# nmcli connection modify ens33 ipv4.addresses 192.168.1.100/24 ipv4.gateway xxx ipv4.dns xxx ipv4.method manual connection.autoconnect yes

rhel 7.0 ： # nmcli connection modify ens33 ipv4.addresses “192.168.1.100/24 192.168.1.1” ipv4.dns xxx ipv4.method manual connection.autoconnect yes ifname eth0 type ethernet

说明：

ipv4.addresses ip地址

ipv4.gateway 网关

ipv4.dns dns地址

ipv4.method 静态/动态ip

connection.autoconnect 系统启动自动连接

ifname 指定硬件设备名称

type 网络类型

(4).激活连接

# nmcli connection up Profile\ 1

(5).删除连接

# nmcli connection delete ens33

(6).配置多个ip地址条件

- 第一个ip必须为静态ip

- nmcli connection modify Profile\ 1 +ipv4.addresses 1.1.1.1/8

# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo