linux将物理网络设备抽象为interface，屏蔽了物理网络设备的多样性，通过驱动程序检测固件信息在linux内核中登记，在数据包收发时通过interface进行交互。网络管理工具包括network服务，NetworkManager服务，ipconfig服务、netstat服务等。在REHL8/centos8中弃用了之前版本中网络管理的network服务，使用NetworkManager服务替代。
NetworkManager主要管理两类对象：connection(网卡连接配置)和device(网卡设备)，device对应的是interface，而connection是供设备使用的配置，二者是多对一的关系，但同时只有一个connection对象生效，其中配置文件依然默认存放在/etc/sysconfig/network-scripts/下，配置方式有两种：
- 通过
nmcli connection add命令配置，会自动生成配置文件； - 手动配置ifcfg文件，通过
nmcli connection reload来使其生效；
1 nmcli命令参数
# nmcli --help
Usage: nmcli [OPTIONS] OBJECT { COMMAND | help }
OPTIONS
-a, --ask ask for missing parameters
-c, --colors auto|yes|no whether to use colors in output
-e, --escape yes|no escape columns separators in values
-f, --fields <field,...>|all|common specify fields to output
-g, --get-values <field,...>|all|common shortcut for -m tabular -t -f
-h, --help print this help
-m, --mode tabular|multiline output mode
-o, --overview overview mode
-p, --pretty pretty output
-s, --show-secrets allow displaying passwords
-t, --terse terse output
-v, --version show program version
-w, --wait <seconds> set timeout waiting for finishing operations
OBJECT
g[eneral] NetworkManagers general status and operations
n[etworking] overall networking control
r[adio] NetworkManager radio switches
c[onnection] NetworkManagers connections
d[evice] devices managed by NetworkManager
a[gent] NetworkManager secret agent or polkit agent
m[onitor] monitor NetworkManager changes
2 创建connection
- 查看当前网络状态
# nmcli connection show
NAME UUID TYPE DEVICE
eth0 5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 ethernet eth0
输出每一行对应一个connection条目。
- 删除当前的connection
# nmcli connection delete eth0
Connection 'eth0' (5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03) successfully deleted.
- 新建一个connection，使其生效
# nmcli connection add ifname eth0 con-name eth1 type ethernet
Connection 'eth1' (7871698e-1a4e-41d0-80c5-24374ced9526) successfully added.
# nmcli connection show
NAME UUID TYPE DEVICE
eth1 e09fedfe-fe0a-4a30-b304-8bc662427e65 ethernet --
此时在/etc/sysconfig/network-scripts/下自动生成了一个ifcfg-eth1的配置文件。
# nmcli connection up eth1
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnec
tion/7)
3 修改connection
修改一个已经存在connection，直接编辑/etc/sysconfig/network-scripts/下对应的配置文件，修改完后：
# nmcli connection reload
或者直接通过nmcli connection modify命令进行修改。
# nmcli connection modify help
Usage: nmcli connection modify { ARGUMENTS | help }
ARGUMENTS := [id | uuid | path] <ID> ([+|-]<setting>.<property> <value>)+
Modify one or more properties of the connection profile.
The profile is identified by its name, UUID or D-Bus path. For multi-valued
properties you can use optional '+' or '-' prefix to the property name.
The '+' sign allows appending items instead of overwriting the whole value.
The '-' sign allows removing selected items instead of the whole value.
ARGUMENTS := remove <setting>
Remove a setting from the connection profile.
Examples:
nmcli con mod home-wifi wifi.ssid rakosnicek
nmcli con mod em1-1 ipv4.method manual ipv4.addr "192.168.1.2/24, 10.10.1.5/8"
nmcli con mod em1-1 +ipv4.dns 8.8.4.4
nmcli con mod em1-1 -ipv4.dns 1
nmcli con mod em1-1 -ipv6.addr "abbe::cafe/56"
nmcli con mod bond0 +bond.options mii=500
nmcli con mod bond0 -bond.options downdelay
nmcli con mod em1-1 remove sriov
4 修改device名称
# ip link set dev eth0 down
# ip link set dev eth0 name eth01
然后将/etc/sysconfig/network-scripts/下的配置文件中的device字段也进行更新。
# ip link set dev eth01 up
# nmcli connection reload