在 Windows 命令提示字元底下，看 IP 設定第一個想到的指令是 ipconfig，它在 Linux 的對應指令為 ifconfig，可是在 CentOS 7 Minimal 下，這個指令被拿掉了，需要藉由安裝 net-tools 套件才能使用。

  [root@centos7-cli ~]# ifconfig
  -bash: ifconfig: command not found
  [root@centos7-cli ~]# yum install net-tools -y
  Loaded plugins: fastestmirror
  Loading mirror speeds from cached hostfile
   * base: ftp.yzu.edu.tw
   * extras: ftp.yzu.edu.tw
   * updates: ftp.yzu.edu.tw
  Resolving Dependencies
  --> Running transaction check
  ---> Package net-tools.x86_64 0:2.0-0.24.20131004git.el7 will be installed
  --> Finished Dependency Resolution

  Dependencies Resolved

  ==========================================================================================================================
   Package                    Arch                    Version                                   Repository             Size
  ==========================================================================================================================
  Installing:
   net-tools                  x86_64                  2.0-0.24.20131004git.el7                  base                  306 k

  Transaction Summary
  ==========================================================================================================================
  Install  1 Package

  Total download size: 306 k
  Installed size: 918 k
  Downloading packages:
  net-tools-2.0-0.24.20131004git.el7.x86_64.rpm                                                      | 306 kB  00:00:00
  Running transaction check
  Running transaction test
  Transaction test succeeded
  Running transaction
    Installing : net-tools-2.0-0.24.20131004git.el7.x86_64                                                              1/1
    Verifying  : net-tools-2.0-0.24.20131004git.el7.x86_64                                                              1/1

  Installed:
    net-tools.x86_64 0:2.0-0.24.20131004git.el7

  Complete!
  [root@centos7-cli ~]# ifconfig
  ens32: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
          inet 192.168.250.102  netmask 255.255.255.0  broadcast 192.168.250.255
          inet6 fe80::b683:4793:d132:95b1  prefixlen 64  scopeid 0x20<link>
          ether 00:0c:29:98:e7:92  txqueuelen 1000  (Ethernet)
          RX packets 9866  bytes 14050976 (13.4 MiB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 1829  bytes 130448 (127.3 KiB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

  lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
          inet 127.0.0.1  netmask 255.0.0.0
          inet6 ::1  prefixlen 128  scopeid 0x10<host>
          loop  txqueuelen 1000  (Local Loopback)
          RX packets 64  bytes 5696 (5.5 KiB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 64  bytes 5696 (5.5 KiB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

  [root@centos7-cli ~]#

由此可看到目前有一張 NIC 網卡 ens32，目前 IP 為 192.168.250.102/24

另外亦可藉由查看檔案，得知目前 IP 設定。

  [root@centos7-cli ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens32
  TYPE="Ethernet"
  PROXY_METHOD="none"
  BROWSER_ONLY="no"
  BOOTPROTO="dhcp"
  DEFROUTE="yes"
  IPV4_FAILURE_FATAL="no"
  IPV6INIT="yes"
  IPV6_AUTOCONF="yes"
  IPV6_DEFROUTE="yes"
  IPV6_FAILURE_FATAL="no"
  IPV6_ADDR_GEN_MODE="stable-privacy"
  NAME="ens32"
  UUID="2ddf3f8e-f627-4fe7-9b05-bb8a58f506a4"
  DEVICE="ens32"
  ONBOOT="yes"
  [root@centos7-cli ~]#

可看出 ens32 這張網卡，是由 DHCP 取得 IP，開機會自動啟用連線

使用 nmcli device show 指令，我們可以查到更多資訊，包括 Default Gateway 預設閘道與 DNS。

  [root@centos7-cli ~]# nmcli device show
  GENERAL.DEVICE:                         ens32
  GENERAL.TYPE:                           ethernet
  GENERAL.HWADDR:                         00:0C:29:98:E7:92
  GENERAL.MTU:                            1500
  GENERAL.STATE:                          100 (connected)
  GENERAL.CONNECTION:                     ens32
  GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/1
  WIRED-PROPERTIES.CARRIER:               on
  IP4.ADDRESS[1]:                         192.168.250.102/24
  IP4.GATEWAY:                            192.168.250.254
  IP4.ROUTE[1]:                           dst = 0.0.0.0/0, nh = 192.168.250.254, mt = 100
  IP4.ROUTE[2]:                           dst = 192.168.250.0/24, nh = 0.0.0.0, mt = 100
  IP4.DNS[1]:                             192.168.250.254
  IP4.DOMAIN[1]:                          localdomain
  IP6.ADDRESS[1]:                         fe80::b683:4793:d132:95b1/64
  IP6.GATEWAY:                            --
  IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
  IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255

  GENERAL.DEVICE:                         lo
  GENERAL.TYPE:                           loopback
  GENERAL.HWADDR:                         00:00:00:00:00:00
  GENERAL.MTU:                            65536
  GENERAL.STATE:                          10 (unmanaged)
  GENERAL.CONNECTION:                     --
  GENERAL.CON-PATH:                       --
  IP4.ADDRESS[1]:                         127.0.0.1/8
  IP4.GATEWAY:                            --
  IP6.ADDRESS[1]:                         ::1/128
  IP6.GATEWAY:                            --
  [root@centos7-cli ~]#

還有一個 nmcli connection show ens32 指令，可以查看更多資訊，這裡就先不 Demo 了（篇幅站太多了）。

整理一下網卡 ens32 資訊，等下要用：

• IP：將要改為 192.168.250.92/24
• Default Gateway 與 DNS：192.168.250.254

使用 nmcli connection modify ens32 修改網卡 ens32 為固定 IP 192.168.250.92

  [root@centos7-cli ~]# nmcli connection modify ens32 ipv4.addresses 192.168.250.92/24 ipv4.gateway 192.168.250.254 ipv4.dns 192.168.250.254 ipv4.method manual connection.autoconnect yes
  [root@centos7-cli ~]#

接著使用 nmcli connection reload 與 systemctl restart network 指令，重啟網卡，以及 systemctl reboot 重開機。

重開機後，仿照 Day05 使用 ping 指令測試，以及使用以上指令，查看設定是否正確。

其實還有個 nmtui 指令，檢視、設定會更直覺：