Failed to start LSB: Bring up/down networking
遇到這個錯誤好幾次，所以總結了一下排解的幾種方法。
錯誤記錄及排查方法過程：
當我克隆出一台新的centos7的虛擬機的時候，修改了網卡配置文件啟動時，報錯
[root@centos7 ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[root@centos7 ~]#1.2.3.
按照提示輸入systemctl status network.service查看
[root@centos7 ~]# systemctl status network.service
● network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled)
Active: failed (Result: exit-code) since Mon 2017-03-13 23:24:37 CST; 16s ago
Docs: man:systemd-sysv-generator(8)
Process: 2878 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 network[2878]: RTNETLINK answers: File exists
Mar 13 23:24:37 centos7 systemd[1]: network.service: control process exited, code=exited status=1
Mar 13 23:24:37 centos7 systemd[1]: Failed to start LSB: Bring up/down networking.
Mar 13 23:24:37 centos7 systemd[1]: Unit network.service entered failed state.
Mar 13 23:24:37 centos7 systemd[1]: network.service failed.1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.
無奈去百度了一下，找到解決方法，說是centos7沒有70-persistent-net.rules這個文件，所以新克隆的機器需要配置mac地址。
通過ip a命令查看mac地址是00:0c:29:0c:15:49
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:0c:15:49 brd ff:ff:ff:ff:ff:ff1.2.
然后在配置文件中加入這一行（如果存在的話只修改就可以）
HWADDR=00:0c:29:0c:15:491.
重啟生效
[root@centos7 ~]# systemctl restart network.service
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[root@centos7 ~]#1.2.3.
發現依然有這個錯誤
查看啟動日志
Mar 13 23:51:35 centos7 systemd: Starting LSB: Bring up/down networking...
Mar 13 23:51:35 centos7 network: Bringing up loopback interface: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Mar 13 23:51:35 centos7 network: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Mar 13 23:51:35 centos7 network: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Mar 13 23:51:35 centos7 network: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
Mar 13 23:51:35 centos7 network: [ OK ]
Mar 13 23:51:36 centos7 network: Bringing up interface eth0: Error: Connection activation failed: No suitable device found for this connection.
Mar 13 23:51:36 centos7 network: [FAILED]
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 network: RTNETLINK answers: File exists
Mar 13 23:51:36 centos7 systemd: network.service: control process exited, code=exited status=1
Mar 13 23:51:36 centos7 systemd: Failed to start LSB: Bring up/down networking.
Mar 13 23:51:36 centos7 systemd: Unit network.service entered failed state.
Mar 13 23:51:36 centos7 systemd: network.service failed.1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.
發現無法加載/etc/sysconfig/network-scripts/ifcfg-lo文件
給NetworkManager-wait-online服務設置開機自啟動
systemctl enable NetworkManager-wait-online.service1.
然后重啟網卡
[root@centos7 ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[root@centos7 ~]#1.2.3.
查看日志
Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'1.
這個錯誤依然存在
systemctl stop NetworkManager
systemctl disable NetworkManager1.2.
將 NetworkManager關閉，然后重啟網卡，查看日志
Mar 14 00:31:27 centos7 systemd: Starting LSB: Bring up/down networking...
Mar 14 00:31:27 centos7 network: Bringing up loopback interface: [ OK ]
Mar 14 00:31:28 centos7 network: Bringing up interface eth0: ERROR : [/etc/sysconfig/network-scripts/ifup-eth] Device eth0 does not seem to be present, delaying initialization.
Mar 14 00:31:28 centos7 /etc/sysconfig/network-scripts/ifup-eth: Device eth0 does not seem to be present, delaying initialization.
Mar 14 00:31:28 centos7 network: [FAILED]
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 network: RTNETLINK answers: File exists
Mar 14 00:31:28 centos7 systemd: network.service: control process exited, code=exited status=1
Mar 14 00:31:28 centos7 systemd: Failed to start LSB: Bring up/down networking.
Mar 14 00:31:28 centos7 systemd: Unit network.service entered failed state.
Mar 14 00:31:28 centos7 systemd: network.service failed.
Mar 14 00:33:42 centos7 dhclient[3813]: DHCPREQUEST on eno16777736 to 10.0.0.254 port 67 (xid=0x4d17f187)
Mar 14 00:33:42 centos7 dhclient[3813]: DHCPACK from 10.0.0.254 (xid=0x4d17f187)1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.
那個錯誤已經不見了，但是重啟網卡
[root@centos7 ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[root@centos7 ~]#1.2.3.
依然是這個錯誤，然后我又重新百度，說虛擬機設置中的兩個連接選項（已連接和啟動時連接）沒有選擇也會報同樣的錯，但是我的已經連接，問題依然存在，到底是因為什么呢？再次查找方法。
結果這次認真看了日志報錯后發現是說eth0這個文件找不到
Mar 14 00:36:39 centos7 network: Bringing up interface eth0: ERROR : [/etc/sysconfig/network-scripts/ifup-eth] Device eth0 does not seem to be present, delaying initialization.
Mar 14 00:36:39 centos7 /etc/sysconfig/network-scripts/ifup-eth: Device eth0 does not seem to be present, delaying initialization.1.2.
原來是之前做優化的時候將7的網卡名改成了eth0（眾所周知7的網卡名是eno后面隨機 一串數字），生成菜單時沒有生效，那么在此生效一下
注意網卡配置名是已經修改成eth0以后執行下面操作，一共修改的地方有三處，第一處網卡名：/etc/sysconfig/network-scripts/ifcfg-eth0 ，第二處配置文件里面：NAME=eth0 ，第三處也是配置文件里面：DEVICE=eth0
修改/etc/sysconfig/grub，添加net.ifnames=0 biosdevname=0
[root@centos7 ~]# cat /etc/sysconfig/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=128M rd.lvm.lv=centos/root rhgb quiet net.ifnames=0 biosdevname=0"
GRUB_DISABLE_RECOVERY="true"
[root@centos7 ~]#1.2.3.4.5.6.7.8.9.
生成菜單
[root@centos7 ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux p_w_picpath: /boot/vmlinuz-3.10.0-327.el7.x86_64
Found initrd p_w_picpath: /boot/initramfs-3.10.0-327.el7.x86_64.img
Found linux p_w_picpath: /boot/vmlinuz-0-rescue-8058723e5e754d3aabc51842d9108e3b
Found initrd p_w_picpath: /boot/initramfs-0-rescue-8058723e5e754d3aabc51842d9108e3b.img
done
[root@centos7 ~]#1.2.3.4.5.6.7.8.
最后reboot重啟
最后登錄后正常