Shulou(Shulou.com)06/02 Report--

After installing centos 8, the following error occurs when you restart the network

The error message is as follows:

Failed to start network.service: Unit network.service not found.

It means that the network service cannot be restarted because the network.service network service cannot be found.

On rhel8 (including centos8), you don't see any script files in / etc/sysconfig/network-scripts/, and there's no traditional network.service. Therefore, network configuration can only be done through other methods, including the NM command toolset. In other words, on rhel8, NM must be turned on, or the network cannot be used.

Manually configure static IP

Cat / etc/sysconfig/network-scripts/ifcfg-ens32TYPE=EthernetPROXY_METHOD=noneBROWSER_ONLY=noBOOTPROTO=staticDEFROUTE=yesIPV4_FAILURE_FATAL=noIPV6INIT=yesIPV6_AUTOCONF=yesIPV6_DEFROUTE=yesIPV6_FAILURE_FATAL=noIPV6_ADDR_GEN_MODE=stable-privacyNAME=ens32UUID=066b4926-b40c-4c28-a5b4-2310d2b96613DEVICE=ens32ONBOOT=yesIPADDR=192.168.1.200NETMASK=255.255.255.0GATEWAY=192.168.1.254DNS1=223.5.5.5PREFIX=24

Reload the network configuration using nmcli

Nmcli c reload

View

Nmcli cNAME UUID TYPE DEVICEens32 066b4926-b40c-4c28-a5b4-2310d2b96613 ethernet ens32

Supplementary nmcli command

How to use nmcli

Nmcli is very similar to the linux ip command and cisco switch command, and supports tab completion (see Tips at the end of this article). You can also view help through-h,-- help, and help at the end of the command.

Nmcli-- helpUsage: nmcli [OPTIONS] OBJECT {COMMAND | help} OPTIONS-o [verview] overview mode (hide default values)-t [erse] terse output-p [retty] pretty output-m [ode] tabular | multiline output mode-c [olors] auto | yes | no whether to use colors in output-f [ields] | all | common specify fields to output-g [et-values] | all | common shortcut for-m tabular-tmurf-e [scape] yes | no escape columns separators in values-a [sk] ask for missing parameters-s [how-secrets] allow displaying passwords- W [ait] set timeout waiting for finishing operations-v [ersion] show program version-h [elp] print this help OBJECTg [eneral] NetworkManager's general status and operationsn [etworking] overall networking controlr [adio] NetworkManager radio switchesc [onnection] NetworkManager's connectionsd [evice] devices managed by NetworkManagera [gent] NetworkManager secret agent or polkit agentm [onitor] monitor NetworkManager changes

There are two commands that are most commonly used in nmcli:

Nmcli connection

Translated as connection, it can be understood as a configuration file, which is equivalent to ifcfg-ethX. Can be abbreviated to nmcli c

Nmcli device

Translation device, can be understood as the actual existence of the network card (including physical network card and virtual network card). Can be abbreviated to nmcli d

In NM, there are two dimensions: connection and device, which is a many-to-one relationship. If you want to equip a network card with ip, first of all, NM must be able to manage the network card. The network card that exists in the device (that is, what nmcli d can see) is the NM nanotube. Next, you can configure multiple connections for a device (that is, what nmcli c can see), and each connection can be understood as an ifcfg profile. Only one connection can be active on a device at a time. Connections can be switched through nmcli c up.

Connection has two states:

Active (colored font): indicates that the connection is currently in effect, inactive (normal font): indicates that the connection is not valid at present

Device has four common states:

Connected: has been managed by NM, and currently there is an active connectiondisconnected: managed by NM, but currently there is no active connectionunmanaged: not managed by NM unavailable: not available, NM cannot be managed, usually occurs when the Nic link is down (such as ip link set ens32 down)

A list of commonly used nmcli commands

# View ip (similar to ifconfig, ip addr) nmcli # create connection, configure static ip (equivalent to configuration ifcfg, where BOOTPROTO=none, and ifup start) nmcli c add type ethernet con-name ens32 ifname ens32 ipv4.addr 192.168.1.100 ipv4.gateway 192.168.1.1 ipv4.method manual # create connection, configure dynamic ip (equivalent to configuration ifcfg, where BOOTPROTO=dhcp And ifup start) nmcli c add type ethernet con-name ens32 ifname ens32 ipv4.method auto# modify ip (non-interactive) nmcli c modify ens32 ipv4.addr '192.168.1.200/24'nmcli c up ens32# modify ip (interactive) nmcli c edit ens32nmcli > goto ipv4.addressesnmcli ipv4.addresses > changeEdit' addresses' value: 192.168.1.200/24Do you also want to set 'ipv4.method' to' manual'? [yes]: yesnmcli ipv4 > savenmcli ipv4 > activatenmcli ipv4 > quit# enable connection (equivalent to ifup) nmcli c up ens32# stop connection (equivalent to ifdown) nmcli c down# delete connection (similar to ifdown and delete ifcfg) nmcli c delete ens32# View connection list nmcli c show# View connection details nmcli c show ens32# reloads all ifcfg or route to connection (not effective immediately) nmcli c reload# overloads specified ifcfg or route to connection (not immediately Effective) nmcli c load / etc/sysconfig/network-scripts/ifcfg-ens32nmcli c load / etc/sysconfig/network-scripts/route-ens32# effective immediately connection There are three ways to nmcli c up ens32nmcli d reapply ens32nmcli d connect ens32# view device list nmcli d # view all device details nmcli d show# view details of specified device nmcli d show ens32# activate network card nmcli d connect ens32# turn off wireless network (NM default enable wireless network) nmcli r all off# view NM nanotube status nmcli n # turn on NM nanotube nmcli n on# close NM nanotube (careful execution ) nmcli n off# listening event nmcli m # View the status of NM itself nmcli# check whether NM is available online nm-online

All mentioned ifcfg refer to / etc/sysconfig/network-scripts/ifcfg-ens32 and / etc/sysconfig/network-scripts/route-ens32

Nmcli connection focus

The first column of nmcli c showNAME UUID TYPE DEVICEens32 066b4926-b40c-4c28-a5b4-2310d2b96613 ethernet ens32 is the name of connection, which is abbreviated to con-name (note that con-name is not the name of the network card). The second column is the UUID of connection and the last column is the name of the network card (device name in standard parlance). You can view device through nmcil d

You need to specify an identity when operating on connection, which can be con-name, UUID, or the full path of ifcfg if there is an ifcfg file, that is, / etc/sysconfig/network-scripts/ifcfg-ens32

Nmcli c show ens32nmcli c show cae3f1ef-e79a-46c3-8e0c-946b91a65e11nmcli c show / etc/sysconfig/network-scripts/ifcfg-ens32

Con-name of nmcli c

At the same time, it corresponds to the file name of the ifcfg and the NAME=, in the content. This parameter indicates the name of the connection, which does not need to be the same as the name of the network card. Multiple connections can be created for a device (device), but only one connection can take effect at a time. When there are multiple connections, nmcli c delete deletes the current connection and automatically selects other connections for the same device to take effect. You can use nmcli c up to make the specified connection switch effective.

Note: modifying con-name through nmcli c modify only corresponds to modifying the NAME in the ifcfg file, not changing the ifcfg file name.

Ipv4.method of nmcli c

The BOOTPROTO corresponding to the contents of the ifcfg file defaults to auto and corresponds to BOOTPROTO=dhcp. In this case, if you specify ip, it may cause the Nic to have both ip and static ip assigned by dhcp. Set to manual to indicate BOOTPROTO=none, that is, only static ip.

Example: create a connection (connection)

Nmcli c add type ethernet con-name ens32-test ifname ens32 ipv4.addresses' 192.168.1.100 ipv4.gateway 24192.168.1.10q32 'ipv4.routes' 10.0.0.0 ipv4.method manualtype ethernet: you must specify a type when creating a connection. There are many types. You can see it through nmcli c add type-h, which is specified here as ethernet. Con-name ens32 ifname ens32: the first ethX represents the name of the connection, which can be defined arbitrarily, without having to be the same as the network card name; the second ethX represents the network card name, and the ethX must be visible in nmcli d. Ipv4.addresses' 192.168.1.100 ip 24192.168.1.101q32: configure 2 ip addresses, 192.168.1.100 Charpy 24 and 192.168.1.101/32ipv4.gateway 192.168.1.254: the gateway is 192.168.1.254ipv4.dns' 8.8.8.8, 4.4.4.4.4Universe DNS is 8.8.8.8 and 4.4.4.4ipv4.method manual: configure static IP

The corresponding ifcfg and dns are

# / etc/sysconfig/network-scripts/ifcfg-ens32-testTYPE=EthernetPROXY_METHOD=noneBROWSER_ONLY=noBOOTPROTO=noneIPADDR=192.168.1.100PREFIX=24IPADDR1=192.168.1.101PREFIX1=32GATEWAY=192.168.1.254DNS1=8.8.8.8DNS2=4.4.4.4DEFROUTE=yesIPV4_FAILURE_FATAL=noIPV6INIT=yesIPV6_AUTOCONF=yesIPV6_DEFROUTE=yesIPV6_FAILURE_FATAL=noIPV6_ADDR_GEN_MODE=stable-privacyNAME=ens32-testUUID=9a10ad89-437c-4caa-949c-a394a6d28c8dDEVICE=ens32ONBOOT=yes # / etc/resolv.confnameserver 8.8.8.8nameserver 4.4.4.4

At this point, you should be able to see an additional connection through nmcli c

Note: if this is the first connection created for ethX, it will take effect automatically; if a connection already exists, the connection will not take effect automatically, and you can perform nmcli c up ethX-test to switch it to take effect

Nmcli device focus

Nmcli d connect ens32

NM manages the specified network card and refreshes the active connection corresponding to the network card (if the connection configuration has been modified before); if there is an connection but is inactive, automatically select a connection and make it active; if there is no connection, automatically generate one and make it active.

Nmcli d disconnect ens32

Let NM not manage the specified network card for the time being. This operation will not change the link status of the actual network card, but will only make the corresponding connection become inactive. If you restart the system, it will automatically connect. In addition, if you manually delete all the connection of the network card, the status of the network card will automatically become disconnected.

Nmcli d reapply ens32

It is specially used to refresh the connection, provided that the device of the Nic is in the connected state, otherwise an error will be reported.

Nmcli d set ens32 autoconnect yes | no managed yes | no

You can set whether to connect and manage automatically, but it can only be used in the current boot state after testing. If both parameters are set to no, and then restart the system, it will automatically return to the state of connected and managed yes. So the command is of little use. Note: if managed is set to no, nmcli c reload will read the configuration file, but it will not take effect immediately, then if you execute nmcli c up ethX, it will take effect immediately, and managed will automatically become yes.

The above is the whole content of this article, I hope it will be helpful to your study, and I also hope that you will support it.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.