centos6 start the repair process:
Experiment 1: Delete initramfs-2.6.32-754.el6.x86_64.img recovery
This document is very important initramfs-2.6.32-754.el6.x86_64.img, as an important file to start the system, load the driver file system.
Post press esc to enter rescue mode
chroot / mnt / sysimage root switch
mkinitrd / boot / ininramfs-`uname -r`.img `uname -r` can repair this file
sync sync sync sync to disk
reboot
Experiment II: the destruction of the 446 byte sectors, repair
dd if=/dev/zero of=/dev/sda bs=1 count=446
hexdump -C / dev / sda -n 512 -v first 446 bytes of the query has been destroyed
Restart Press esc to enter rescue mode
chroot / mnt / sysimage root switch
grub-install / dev / sda sda disk repair equipment
sync sync sync sync to disk
exit
reboot
Experiment three: Password crack centos6
1 Start grub interface
2 . Add a 1 input single-user mode
3. Press passwd to change the password
4 reboot
Add centos6 single-user mode password, you can not break:
grub-crypt
[Root @ centos6 ~] # grub-crypt command to create a password
Password: password
Retype password: password
$6$9M4MYaaShQLTXYAU$cIFuNc7SpKZw1NLCBG3/yoi6UHAWiMNxzBtDl3TGYzsmx3lRDjNRoRbNLEN8v8UsWldud2HHFRVqhbSFsqdly0
CD crack the code:
Enter rescue mode
chroot /mnt/sysimage
vim /boot/gub/grub.conf comment out the line to passwd
reboot
Experiment 4: Remove grub.conf
1. Boot error jump directly to the grub interface to enter content:
kernel /vmlinuz-2.6.32-2754.e16.x86_64 root=/dev/sda2
initrd /initramfs-2.6.32-275.e16.86_64.img
2. Temporary into the machine
Then modify the configuration file, save a permanent fix:
vim /boot/grub/grub,conf
default=0
timeout=3
kernel /vmlinuz-2.6.32-2754.e16.x86_64 root=/dev/sda2
initrd /initramfs-2.6.32-275.e16.86_64.img
Save and exit, repaired.
Experiment 5: delete all files in the boot, disc repair needs
1. Press the esc reboot into recovery mode: to fix kernel boot-related files
mkdir / mnt / cdrom to mount a new temporary file
mount / dev / sr0 / mnt / cdrom mount the CD
rpm -ivh / mnt / cdrom / Packages / kernel .... --root = / mnt / sysimage (specify the installation path) --force (mandatory installation)
2. Fix grub file
chroot /mnt/sysimage
grub-install /dev/sda
sync sync sync
3. Repair grub.conf file
vim /boot/grub/grub,conf
default=0
timeout=3
kernel / vmlinuz-2. kernel version File root = / dev / sda2
initrd /initramfs-...img file
Save and exit, repair is completed!
Experiment six: delete all files in the boot, and there is no / etc / fstab file, a disc repair
1. Restart Press esc to enter rescue mode
2.mkdir / mnt / rootfs mount a new temporary file
The devices are mounted, determining root root partition:
mount / dev / sda1 / mnt / rootfs determination / dev / sda1 boot partition is
mount /dev/sda2 /mnt/rootfs 确定/dev/sda2为/分区
mount /dev/sda3 /mnt/rootfs 确定/dev/sda3为 data分区
mount /dev/sda5 /mnt/rootfs 确定/dev/sda5为swap 分区
3.最后确定/dev/sda2为根分区进行挂载
mount /dev/sda2 /mnt/rootfs 挂载/dev/sda2设备
4.添加文件内容：
vim /mnt/rootfs/etc/fstab
/dev/sda1 /boot ext4 defaults 0 0
/dev/sda2 / ext4 defaults 0 0
/dev/sda3 /data ext4 defaults 0 0
/dev/sda5 swap swap defaults 0 0
5.重启进入按esc救援模式：去修复内核启动相关文件
mkdir /mnt/cdrom 新建临时挂载文件
mount /dev/sr0 /mnt/cdrom 挂载光盘
rpm -ivh /mnt/cdrom/Packages/kernel.... --root=/mnt/sysimage（指定安装路径） --force(强制安装)
6.修复grub文件
chroot /mnt/sysimage
grub-install /dev/sda
sync sync sync
7.修复grub.conf文件
vim /boot/grub/grub,conf
default=0
timeout=3
kernel /vmlinuz-2.版本内核文件 root=/dev/sda2
initrd /initramfs-...img文件
保存退出，修复完毕！
centos7故障修复流程：
第一种情况：
删除rm -rf /boot/grub2以下的文件进行修复：
1)进入救援模式：
2)然后切换根目录：
chroot /mnt/sysimage
3)生成grub2文件
grub2-install /dev/sda
4)将grub.cfg启动配置文件生成
grub2-mkconfig -o /boot/grub2/grub.cfg
5)sync sync sync sync 同步写入磁盘中
6)reboot就会修复。
第二种情况：
删除rm -rf /boot/下的文件进行恢复：
1)进入救援模式rescue
2)切换根目录：
chroot /mnt/sysimage
3)进行临时挂载
mount /dev/sr0 /mnt
4)修复内核里边的相关启动文件
rpm -ivh /mnt/Packages/kernel-3.10.0-957.el7.x86_64.rpm --force
5)修复grub2文件内容
grub2-install /dev/sda
6)最后修复grub.cfg启动的相关配置文件
grub2-mkconfig -o /boot/grub2/grub.cfg
sync sync sync sync 写入磁盘保存
reboot重启。
centos7破解root口令方法之一：
1.启动是按任意键
2.按e键进入编辑模式
3.将光标移动到linux16开始的行，再行尾添加内核参数rd.break
4.按ctrl+x启动
5.查询当前挂载的跟：mount，得知当前挂载的在sysroot下
6.由于当前根只有只读，需要重新挂载修改权限：
mount -o remount,rw /sysroot 修改当前根权限
chroot /sysroot 切换根
passwd root 修改当前口令
touch ./autorelabel 开机之后selinux对每个文件重新进行贴标签
exit
reboot
破解CentOS7的root口令方法二
按e键进入编辑模式
将光标移动linux16开始的行尾，改为rw init=/sysroot/bin
按ctrl-x启动
chroot /sysroot
passwd root
touch /.autorelabel
exit
reboot
centos7加密，就无法破解密码：
grub2-setpassword 创建口令密码
[root@centos7grub]#cat /boot/grub2/user.cfg 保存口令位置
GRUB2_PASSWORD=grub.pbkdf2.sha512.10000.978E5C106D6A102F6912FF51C37CE674483C0AAE52B84EC4DBB6C08AF818CE83BCA8A9743F31A72AA0BD0AB644A66D34AA774EEDDF913DE22C71A6C4A2826860.2B0701EF272ADE6E518EAA613F966F3C1F5C1150B2F61A04FCC34D2588A1FAB2F75922AB8A5DC5C02AA1A84F5EEE919F8C3DE5526FBCB46EA85082EE98CD6919
[root@centos7grub]#mv /boot/grub2/user.cfg /data 口令文件移动走之后，口令就会失效。
