CentOS7.7 系統下 virbr0 虛擬網卡的維護與管理

 

       在 CentOS 7 系統的安裝過程中，如果有選擇相關虛擬化的的服務安裝系統后，啟動網卡時會發現有一個以網橋連接的私網地址的 virbr0 網卡，這個是因為在虛擬化中有使用到 libvirtd 服務生成的，如果不需要可以關閉后去掉：

 

一、查看IP及網橋設備

查看系統版本：

[root@node ~]# cat /etc/redhat-release 
CentOS Linux release 7.7.1908 (Core)

查看IP地址：

[root@node ~]# ip -4 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    inet 192.168.51.103/24 brd 192.168.51.255 scope global noprefixroute dynamic ens33
       valid_lft 5089sec preferred_lft 5089sec
3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever

查看網橋信息：

[root@node ~]# brctl show
bridge name    bridge id            STP enabled    interfaces
virbr0         8000.525400f9f9fe    yes            virbr0-nic

 

二、使用 brctl 命令管理網橋

brctl 命令的幫助信息：

[root@node ~]# brctl
Usage: brctl [commands] commands: addbr <bridge> add bridge //增加網橋 delbr <bridge> delete bridge //刪除網橋 addif <bridge> <device> add interface to bridge delif <bridge> <device> delete interface from bridge     hairpin       <bridge> <port> {on|off}  turn hairpin on/off
    setageing <bridge> <time> set ageing time setbridgeprio <bridge> <prio> set bridge priority setfd <bridge> <time> set bridge forward delay sethello <bridge> <time> set hello time setmaxage <bridge> <time> set max message age
    setpathcost   <bridge> <port> <cost>    set path cost
    setportprio   <bridge> <port> <prio>    set port priority
    show          <bridge> ]                show a list of bridges
    showmacs      <bridge>                  show a list of mac addrs
    showstp       <bridge>                  show bridge stp info
    stp           <bridge> {on|off}         turn stp on/off

刪除網橋：

[root@node ~]# ifconfig virbr0 down
[root@node ~]# brctl delbr virbr0

 

三、禁用開機自啟動 libvirtd 服務

[root@node ~]# systemctl disable libvirtd.service # 禁用libvirtd 服務開機自啟動
Removed symlink /etc/systemd/system/multi-user.target.wants/libvirtd.service.
Removed symlink /etc/systemd/system/sockets.target.wants/virtlogd.socket.
Removed symlink /etc/systemd/system/sockets.target.wants/virtlockd.socket.
[root@node ~]# systemctl status libvirtd.service
● libvirtd.service - Virtualization daemon
   Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; disabled; vendor preset: enabled)
   Active: inactive (dead) since Sun 2019-12-15 13:31:13 CST; 42min ago
     Docs: man:libvirtd(8)
           https://libvirt.org
 Main PID: 1193 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/libvirtd.service
           ├─1822 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper
           └─1823 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper

Dec 15 11:43:15 node dnsmasq-dhcp[1822]: DHCP, sockets bound exclusively to interface virbr0
Dec 15 11:43:15 node dnsmasq[1822]: no servers found in /etc/resolv.conf, will retry
Dec 15 11:43:15 node dnsmasq[1822]: read /etc/hosts - 2 addresses
Dec 15 11:43:15 node dnsmasq[1822]: read /var/lib/libvirt/dnsmasq/default.addnhosts - 0 addresses
Dec 15 11:43:15 node dnsmasq-dhcp[1822]: read /var/lib/libvirt/dnsmasq/default.hostsfile
Dec 15 13:30:01 node dnsmasq[1822]: reading /etc/resolv.conf
Dec 15 13:30:01 node dnsmasq[1822]: using nameserver 192.168.1.1#53
Dec 15 13:30:01 node dnsmasq[1822]: using nameserver 192.168.51.1#53
Dec 15 13:31:13 node systemd[1]: Stopping Virtualization daemon...
Dec 15 13:31:13 node systemd[1]: Stopped Virtualization daemon.
[root@node ~]# systemctl mask libvirtd.service
Created symlink from /etc/systemd/system/libvirtd.service to /dev/null.

 

四、驗證

[root@node ~]# ip -4 add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    inet 192.168.51.103/24 brd 192.168.51.255 scope global noprefixroute dynamic ens33
       valid_lft 4464sec preferred_lft 4464sec

    結果發現：virbr0 已被刪除。