sudo 的特点

限制用户执行指定的命令 记录用户执行的每一条命令 配置文件（/etc/sudoers）提供集中的用户管理、权限与主机等参数 验证密码的后5分钟内（默认值）无须再让用户再次验证密码

实战演练

环境：Red Hat Enterprise Linux Server release 7.3

1. 测试普通用户能否删除 root 用户创建的文件

[root@localhost ~]# mkdir /test [root@localhost ~]# cd /test [root@localhost test]# touch test.txt [root@localhost test]# mkdir test.dir [root@localhost test]# ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 02:19 test.dir -rw-r--r--. 1 root root 0 Jul 18 02:19 test.txt [root@localhost test]# id test uid=1004(test) gid=1005(test) groups=1005(test) [root@localhost test]# su - test Last login: Thu Jul 18 02:17:11 EDT 2019 on pts/0 [test@localhost ~]$ cd /test [test@localhost test]$ ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 02:19 test.dir -rw-r--r--. 1 root root 0 Jul 18 02:19 test.txt [test@localhost test]$ rm -rf test.dir/ rm: cannot remove ‘test.dir/’: Permission denied [test@localhost test]$ rm -rf test.txt rm: cannot remove ‘test.txt’: Permission denied [test@localhost test]$ ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 02:19 test.dir -rw-r--r--. 1 root root 0 Jul 18 02:19 test.txt

2. 用 visudo 命令配置 sudo

[root@localhost ~]# visudo # 在 /etc/sudoers 配置文件中 root ALL=(ALL) ALL 这一行下面加入 test ALL=(ALL) ALL [root@localhost ~]# cat /etc/sudoers | grep ALL Defaults env_keep += "LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY" root ALL=(ALL) ALL test ALL=(ALL) ALL # %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE, DRIVERS %wheel ALL=(ALL) ALL # %wheel ALL=(ALL) NOPASSWD: ALL %wheel ALL=(ALL) NOPASSWD: ALL # %users ALL=/sbin/mount /mnt/cdrom, /sbin/umount /mnt/cdrom

3. 普通用户结合 sudo 删除 root 用户的文件

[root@localhost ~]# echo "Jaking" | passwd --stdin test Changing password for user test. passwd: all authentication tokens updated successfully. [root@localhost ~]# su - test Last login: Thu Jul 18 02:34:50 EDT 2019 on pts/0 [test@localhost ~]$ cd /test/ [test@localhost test]$ ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 02:19 test.dir -rw-r--r--. 1 root root 0 Jul 18 02:19 test.txt [test@localhost test]$ rm -rf test.dir/ rm: cannot remove ‘test.dir/’: Permission denied [test@localhost test]$ rm -rf test.txt rm: cannot remove ‘test.txt’: Permission denied [test@localhost test]$ sudo rm -rf test.dir/ [sudo] password for test: [test@localhost test]$ ll total 0 -rw-r--r--. 1 root root 0 Jul 18 02:19 test.txt [test@localhost test]$ sudo rm -rf test.txt [test@localhost test]$ ll total 0

4. sudo 免密配置

[test@localhost test]$ sudo cat /etc/shadow [sudo] password for test: root:$6$YZrm6scxO5zzICbR$fOzORb.0Ib9POZzJmrnzOGDqfFySp8X.9p5QpcpnJXWHIJvZcFpXQONyNigwrZbhXtyfnFn5F1mJsdkXS3jEF/::0:99999:7::: bin:*:16925:0:99999:7::: daemon:*:16925:0:99999:7::: adm:*:16925:0:99999:7::: ***省略部分输出信息*** [test@localhost test]$ id test2 uid=1006(test2) gid=1007(test2) groups=1007(test2) [root@localhost ~]# visudo # 在 /etc/sudoers 配置文件中 %wheel ALL=(ALL) NOPASSWD: ALL 这一行的下面 加入test ALL=(ALL) NOPASSWD: ALL [root@localhost ~]# cat /etc/sudoers | grep NOPASSWD # %wheel ALL=(ALL) NOPASSWD: ALL %wheel ALL=(ALL) NOPASSWD: ALL test ALL=(ALL) NOPASSWD: ALL [test@localhost ~]$ sudo cat /etc/shadow # 用普通用户查看 /etc/shadow 文件已经不需要再输入当前登录用户的密码 root:$6$YZrm6scxO5zzICbR$fOzORb.0Ib9POZzJmrnzOGDqfFySp8X.9p5QpcpnJXWHIJvZcFpXQONyNigwrZbhXtyfnFn5F1mJsdkXS3jEF/::0:99999:7::: bin:*:16925:0:99999:7::: daemon:*:16925:0:99999:7::: adm:*:16925:0:99999:7::: ***省略部分输出信息***

5. 配置 sudo 的部分权限

[root@localhost ~]# cd /tmp [root@localhost tmp]# rm -rf * [root@localhost tmp]# ll total 0 [root@localhost tmp]# touch file [root@localhost tmp]# mkdir dir [root@localhost tmp]# ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 03:01 dir -rw-r--r--. 1 root root 0 Jul 18 03:01 file [root@localhost tmp]# whereis cat cat: /usr/bin/cat /usr/share/man/man1/cat.1.gz [root@localhost tmp]# visudo # 把 /etc/sudoers 配置文件中的 test ALL=(ALL) ALL 改为 test ALL=(ALL) /usr/bin/cat [root@localhost ~]# cat /etc/sudoers | grep cat ## Updating the locate database # Defaults specification # Preserving HOME has security implications since many programs test ALL=(ALL) /usr/bin/cat [root@localhost ~]# su - test Last login: Thu Jul 18 03:06:55 EDT 2019 on pts/0 [test@localhost ~]$ sudo cat /etc/shadow # 给 test 用户配置了查看权限 root:$6$YZrm6scxO5zzICbR$fOzORb.0Ib9POZzJmrnzOGDqfFySp8X.9p5QpcpnJXWHIJvZcFpXQONyNigwrZbhXtyfnFn5F1mJsdkXS3jEF/::0:99999:7::: bin:*:16925:0:99999:7::: daemon:*:16925:0:99999:7::: adm:*:16925:0:99999:7::: ***省略部分输出信息*** [test@localhost ~]$ cd /tmp [test@localhost tmp]$ ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 03:06 dir -rw-r--r--. 1 root root 0 Jul 18 03:01 file [test@localhost tmp]$ rm -rf dir # test 用户已经没有了删除权限 rm: cannot remove ‘dir’: Permission denied [test@localhost tmp]$ rm -rf file # test 用户已经没有了删除权限 rm: cannot remove ‘file’: Permission denied [test@localhost tmp]$ ll total 0 drwxr-xr-x. 2 root root 6 Jul 18 03:06 dir -rw-r--r--. 1 root root 0 Jul 18 03:01 file