Linux用戶配置sudo權限(visudo)

sudo的工做過程以下：

1，當用戶執行sudo時，系統會主動尋找/etc/sudoers文件，判斷該用戶是否有執行sudo的權限

2，確認用戶具備可執行sudo的權限後，讓用戶輸入用戶本身的密碼確認

3，若密碼輸入成功，則開始執行sudo後續的命令

4，root執行sudo時不須要輸入密碼(eudoers文件中有配置root ALL=(ALL) ALL這樣一條規則)

5，若欲切換的身份與執行者的身份相同，也不須要輸入密碼

 

visudo使用vi打開/etc/sudoers文件，可是在保存退出時，visudo會檢查內部語法，避免用戶輸入錯誤信息

visudo須要root權限

[hear@hear ~]$ visudo
visudo: /etc/sudoers: Permission denied   # 權限不夠
visudo: /etc/sudoers: Permission denied
[hear@hear ~]$ 

　再root用戶使用visudo命令打開sudo配置文件

## Sudoers allows particular users to run various commands as
## the root user, without needing the root password.
## 該文件容許特定用戶像root用戶同樣使用各類各樣的命令，而不須要root用戶的密碼
##
## Examples are provided at the bottom of the file for collections
## of related commands, which can then be delegated out to particular
## users or groups.
## 在文件的底部提供了不少相關命令的示例以供選擇，這些示例均可以被特定用戶或
## 用戶組所使用 
##
## This file must be edited with the 'visudo' command.
## 該文件必須使用"visudo"命令編輯
 
## Host Aliases
## Groups of machines. You may prefer to use hostnames (perhaps using 
## wildcards for entire domains) or IP addresses instead.
## 對於一組服務器，你可能會更喜歡使用主機名（多是全域名的通配符）
## 、或IP地址，這時能夠配置主機別名
# Host_Alias     FILESERVERS = fs1, fs2
# Host_Alias     MAILSERVERS = smtp, smtp2
 
## User Aliases
## These aren't often necessary, as you can use regular groups
## (ie, from files, LDAP, NIS, etc) in this file - just use %groupname 
## rather than USERALIAS
## 這並不很經常使用，由於你能夠經過使用組來代替一組用戶的別名
# User_Alias ADMINS = jsmith, mikem
 
## Command Aliases
## These are groups of related commands...
## 指定一系列相互關聯的命令（固然能夠是一個）的別名，經過賦予該別名sudo權限，
## 能夠經過sudo調用全部別名包含的命令，下面是一些示例
 
## Networking 網絡操做相關命令別名
# Cmnd_Alias NETWORKING = /sbin/route, /sbin/ifconfig, /bin/ping, /sbin/dhclient
, /usr/bin/net, /sbin/iptables, /usr/bin/rfcomm, /usr/bin/wvdial, /sbin/iwconfig
, /sbin/mii-tool
 
## Installation and management of software 軟件安裝管理相關命令別名
# Cmnd_Alias SOFTWARE = /bin/rpm, /usr/bin/up2date, /usr/bin/yum
 
## Services 服務相關命令別名
# Cmnd_Alias SERVICES = /sbin/service, /sbin/chkconfig
 
## Updating the locate database 本地數據庫升級命令別名
# Cmnd_Alias LOCATE = /usr/bin/updatedb
 
## Storage 磁盤操做相關命令別名
# Cmnd_Alias STORAGE = /sbin/fdisk, /sbin/sfdisk, /sbin/parted, /sbin/partprobe
, /bin/mount, /bin/umount
 
## Delegating permissions 代理權限相關命令別名
# Cmnd_Alias DELEGATING = /usr/sbin/visudo, /bin/chown, /bin/chmod, /bin/chgrp 
 
## Processes 進程相關命令別名
# Cmnd_Alias PROCESSES = /bin/nice, /bin/kill, /usr/bin/kill, /usr/bin/killall
 
## Drivers 驅動命令別名
# Cmnd_Alias DRIVERS = /sbin/modprobe
 
# Defaults specification
 
#
# Disable "ssh hostname sudo <cmd>", because it will show the password in clear. 
#         You have to run "ssh -t hostname sudo <cmd>".
# 一些環境變量的相關配置，具體狀況可見man soduers
Defaults    requiretty
 
Defaults    env_reset
Defaults    env_keep =  "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS_COLORS"
Defaults    env_keep += "MAIL PS1 PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE"
Defaults    env_keep += "LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES"
Defaults    env_keep += "LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE"
Defaults    env_keep += "LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY"
 
Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin
 
## Next comes the main part: which users can run what software on 
## which machines (the sudoers file can be shared between multiple
## systems).
## 下面是規則配置：什麼用戶在哪臺服務器上能夠執行哪些命令（sudoers文件能夠在多個系統上共享）
## Syntax(語法):
##
## 	user	MACHINE=COMMANDS 用戶 登陸的主機=（能夠變換的身份） 能夠執行的命令
##
## The COMMANDS section may have other options added to it.
## 命令部分能夠附帶一些其它的選項
##
## Allow root to run any commands anywhere 
## 容許root用戶執行任意路徑下的任意命令
root	ALL=(ALL) 	ALL
 
## Allows members of the 'sys' group to run networking, software, 
## service management apps and more.
## 容許sys中戶組中的用戶使用NETWORKING等全部別名中配置的命令
# %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE
, DRIVERS
 
## Allows people in group wheel to run all commands
## 容許wheel用戶組中的用戶執行全部命令
%wheel	ALL=(ALL)	ALL
 
## Same thing without a password
## 容許wheel用戶組中的用戶在不輸入該用戶的密碼的狀況下使用全部命令
# %wheel	ALL=(ALL)	NOPASSWD: ALL
 
## Allows members of the users group to mount and unmount the 
## cdrom as root
## 容許users用戶組中的用戶像root用戶同樣使用mount、unmount、chrom命令
# %users  ALL=/sbin/mount /mnt/cdrom, /sbin/umount /mnt/cdrom
 
## Allows members of the users group to shutdown this system
## 容許users用戶組中的用戶關閉localhost這臺服務器
# %users  localhost=/sbin/shutdown -h now
 
## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment)
## 讀取放置在/etc/sudoers.d/文件夾中的文件（此處的#不意味着這是一個聲明）
#includedir /etc/sudoers.d