Linux system network management
What is the network?
Network card configuration file
nmcli
The internet
IP address: The address used to identify the machine, similar to an ID number. The only public network in the world ipv4 ipv6
DNS: domain name service, which resolves the domain name of a website to the host of the website
Gateway: Gateway, our router is the gateway.
ifconfig: View all network card information
ifconfig ens33: View the information of the fixed network card
ip addr: view network card information
Network card configuration file
/etc/sysconfig/network-scripts
ens33 == ifcfg-ens33
ens35 == ifcfg-ens35
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none" ##none static static dhcp dynamic
DEFROUTE="yes" ## Default routing
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes "
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33" ## NIC name
UUID="e20ba92f-11c2-49b4-8542-36b5a3879173" ## NIC UUID unique
DEVICE="ens33"
ONBOOT="yes" ## yes Turn on the network card automatically when booting
IPADDR=192.168.1.199 ## IP address
NETMASK=255.255.255.0 ## Subnet mask
centos7: systemctl restart network
nmcli
nmcli c reload
nmcli c up xxx
experiment
Add an experimental network card
Modify the IP address to
192.168.1.188
255.255.255.0
192.168.1.1cp ifcfg-ens33 ifcfg-ens37
[root@myserver network-scripts]# cat ifcfg-ens37
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none"
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="ens37"
DEVICE="ens37"
ONBOOT="yes"
IPADDR=192.168.1.188
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
nmcli c reload
ifdown ens37
ifup ens37
[root@myserver network-scripts]# ifdown ens37
Connection 'ens37' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/9)
[root@myserver network-scripts]# ifconfig ens37
ens37: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 00:0c:29:94:17:3a txqueuelen 1000 (Ethernet)
RX packets 182 bytes 19010 (18.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 286 bytes 31958 (31.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@myserver network-scripts]# ifup ens37
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/10)
[root@myserver network-scripts]# ifconfig ens37
ens37: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.188 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::8568:3e1a:817f:59c0 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:94:17:3a txqueuelen 1000 (Ethernet)
RX packets 193 bytes 19790 (19.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 306 bytes 34192 (33.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
nmcli
View network card information
# nmcli connection
# nmcli con xxx
displays specific network interface information
# nmcli connection show xxx
displays all active connections
# nmcli connection show --active
deletes a network card connection
# nmcli connection delete
ens37 adds an IP (IPADDR) to ens37
# nmcli connection modify ens37 ipv4.addresses 192.168.1.189
add a subnet mask to xxx (NETMASK)
# nmcli connection modify ens37 ipv4.addresses 192.168.1.189/24
IP acquisition mode is set to manual (BOOTPROTO=static/none)
# nmcli connection modify ens37 ipv4.method manual
add an ipv4
# nmcli connection modify ens37 +ipv4.addresses 192.168.1.189/24
delete an ipv4
# nmcli connection modify ens37 -ipv4.addresses 192.168.1.189/24
add a gateway (GATEWAY)
# nmcli connection modify ens37 ipv4.gateway 192.168.0.2
can be written in one piece:
# nmcli connection modify ens37 ipv4.dns 114.114.114.114 ipv4.gateway 192.168.0.1
add DNS
# nmcli connection modify ens37 ipv4.dns 114.114.114.114
delete DNS
# nmcli connection modify ens37 -ipv4.dns 114.114.114.114
Use nmcli to
reload the network configuration # nmcli c reload
If there is no xxx connection before, it will automatically take effect after the previous reload
# nmcli c up ens37
[root@myserver ~]# cd /etc/sysconfig/network-scripts/ [root@myserver network-scripts]# ls ifcfg-ens33 ifcfg-ens37 ifcfg-ens37-1 [root@myserver network-scripts]# mv ifcfg-ens37 ifcfg-ens37~~~~ [root@myserver network-scripts]# ls ifcfg-ens33 ifcfg-ens37~~~~ ifcfg-ens37-1 [root@myserver network-scripts]# cd [root@myserver ~]# [root@myserver ~]# nmcli connection modify ens37 ipv4.addresses 192.168.1.189 [root@myserver ~]# ifconfig ens37 ens37: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.188 netmask 255.255.255.255 broadcast 0.0.0.0 inet6 fe80::20c:29ff:fe94:173a prefixlen 64 scopeid 0x20<link> ether 00:0c:29:94:17:3a txqueuelen 1000 (Ethernet) RX packets 449 bytes 47699 (46.5 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 530 bytes 59159 (57.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@myserver ~]# nmcli connection reload [root@myserver ~]# ifconfig ens37 ens37: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.188 netmask 255.255.255.255 broadcast 0.0.0.0 inet6 fe80::20c:29ff:fe94:173a prefixlen 64 scopeid 0x20<link> ether 00:0c:29:94:17:3a txqueuelen 1000 (Ethernet) RX packets 458 bytes 48335 (47.2 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 530 bytes 59159 (57.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@myserver ~]# nmcli connection up ens37 Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/13) [root@myserver ~]# ifconfig ens37 ens37: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.189 netmask 255.255.255.255 broadcast 0.0.0.0 inet6 fe80::20c:29ff:fe94:173a prefixlen 64 scopeid 0x20<link> ether 00:0c:29:94:17:3a txqueuelen 1000 (Ethernet) RX packets 500 bytes 52058 (50.8 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 582 bytes 64767 (63.2 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0