權限管理:
ls -l
rwxrwxrwx:
左三位:定義user(owner)的權限
中三位:定義group的權限;
右三位:定義other的權限
進程安全上下文:
進程對文件的訪問權限應用模型:
進程的屬主與文件的屬主是否相同;如果相同,則應用屬主權限;
否則,則檢查進程的屬主是否屬於文件的屬組;如果是,則應用屬組權限;
否則,就只能應用other的權限;
權限:
r:readable, 讀
w:writable, 寫
x:excutable,執行
文件:
r:可獲取文件的數據;
w: 可修改文件的數據;
x:可將此文件運行爲進程;
目錄:
r:可使用ls命令獲取其下的所有文件列表;
w: 可修改此目錄下的文件列表;即創建或刪除文件;
x: 可cd至此目錄中,且可使用ls -l來獲取所有文件的詳細屬性信息;
mode:rwxrwxrwx
ownership:user, group
權限組合機制:
--- 000 0
--x 001 1
-w- 010 2
-wx 011 3
r-- 100 4
r-x 101 5
rw- 110 6
rwx 111 7
權限管理命令:
chmod命令:
chmod [OPTION]... MODE[,MODE]... FILE...
chmod [OPTION]... OCTAL-MODE FILE...
chmod [OPTION]... --reference=RFILE FILE...
三類用戶:
u:屬主
g:屬組
o:其它
a: 所有
(1) chmod [OPTION]... MODE[,MODE]... FILE...
MODE表示法:
賦權表示法:直接操作一類用戶的所有權限位rwx;
u=
g=
o=
a=
授權表示法:直接操作一類用戶的一個權限位r,w,x;
u+, u-
g+, g-
o+, o-
a+, a-
(2) chmod [OPTION]... OCTAL-MODE FILE...
(3) chmod [OPTION]... --reference=RFILE FILE...
選項:
-R, --recursive:遞歸修改
注意:用戶僅能修改屬主爲自己的那些文件的權限;
從屬關係管理命令:chown, chgrp
chown命令:
chown [OPTION]... [OWNER][:[GROUP]] FILE...
chown [OPTION]... --reference=RFILE FILE...
選項:
-R:遞歸修改
chgrp命令:
chgrp [OPTION]... GROUP FILE...
chgrp [OPTION]... --reference=RFILE FILE...
注意:僅管理員可修改文件的屬主和屬組;
練習:
1、複製/etc/skel目錄爲/home/tuser1,要求/home/tuser1及其內部文件的屬組和其它用戶均沒有任何訪問權限;
cp -r /etc/skel /home/tuser1
[root@Pikachu ~]# cp -r /etc/skel /home/tuser1
[root@Pikachu ~]# ll /home/
total 4
drwx------. 15 PIkachu PIkachu 4096 Oct 6 14:57 PIkachu
drwx------ 3 60606 50103 78 Oct 15 00:03 PIP2
drwx------ 3 60000 60000 78 Oct 15 00:04 PIP6
drwx------ 3 60001 1001 78 Oct 15 00:04 PIP61
drwx------ 3 50100 50100 78 Oct 15 00:01 PIPI
drwx------ 3 60100 50101 78 Oct 15 00:01 PIPI2
drwx------ 3 60500 50102 78 Oct 15 00:02 PIPI3
drwxr-xr-x 3 root root 78 Oct 21 21:54 tuser1
2、編輯/etc/group文件,添加組hadoop ;
[root@Pikachu ~]# vim /etc/group
在最後一行按i鍵進入編輯模式,輸入 : hadoop:x:1004
按esc鍵進入命令行模式
:wq 回車鍵保存退出
[root@Pikachu ~]# grep hadoop /etc/group
hadoop:x:1004
3、手動編輯/etc/passwd文件新增一行,添加用戶hadoop,其基本組ID爲hadoop組的id號其家目錄爲/home/hadoop ;
[root@Pikachu ~]# vim /etc/passwd
在最後一行按i鍵進入編輯模式,輸入 : hadoop:x:1004:1004::/home/hadoop:/bin/bash
按esc鍵進入命令行模式
:wq 回車鍵保存退出
[root@Pikachu ~]# grep hadoop /etc/passwd
hadoop:x:1004:1004::/home/hadoop:/bin/bash
4、複製/etc/skel目錄爲/home/hadoop,要求修改hadoop目錄的屬組和其它用戶沒有任何訪問權限;
cp -rv /etc/skel /home/hadoop
[root@Pikachu ~]# cp -rv /etc/skel /home/hadoop
‘/etc/skel’ -> ‘/home/hadoop’
‘/etc/skel/.mozilla’ -> ‘/home/hadoop/.mozilla’
‘/etc/skel/.mozilla/extensions’ -> ‘/home/hadoop/.mozilla/extensions’
‘/etc/skel/.mozilla/plugins’ -> ‘/home/hadoop/.mozilla/plugins’
‘/etc/skel/.bash_logout’ -> ‘/home/hadoop/.bash_logout’
‘/etc/skel/.bash_profile’ -> ‘/home/hadoop/.bash_profile’
‘/etc/skel/.bashrc’ -> ‘/home/hadoop/.bashrc’
[root@Pikachu ~]# chmod -R 700 /home/hadoop
[root@Pikachu ~]# ll -d /home/hadoop
drwx------ 3 root root 78 Oct 21 22:06 /home/hadoop
5、修改/home/hadoop目錄及其內部所有文件的屬主爲hadoop,屬組爲hadoop ;
[root@Pikachu ~]# chown -R hadoop:hadoop /home/hadoop
[root@Pikachu ~]# ll -d /home/hadoop
drwx------ 3 hadoop hadoop 78 Oct 21 22:06 /home/hadoop
6、顯示/proc/meminfo文件中以大寫或小寫S開頭的行;用兩種方式;
[root@Pikachu ~]# grep "^[Ss]" /proc/meminfo;grep -i "^s" /proc/meminfo
grep: /proc/meminfo;grep: No such file or directory
grep: ^s: No such file or directory
/proc/meminfo:SwapCached: 0 kB
/proc/meminfo:SwapTotal: 2097148 kB
/proc/meminfo:SwapFree: 2097148 kB
/proc/meminfo:Shmem: 8624 kB
/proc/meminfo:Slab: 67024 kB
/proc/meminfo:SReclaimable: 28804 kB
/proc/meminfo:SUnreclaim: 38220 kB
7、顯示/etc/passwd文件中其默認shell爲非/sbin/nologin的用戶;
[root@Pikachu ~]# grep -v "nologin$" /etc/passwd | cut -d: -f1
root
sync
shutdown
halt
PIkachu
hadoop
8、顯示/etc/passwd文件中其默認shell爲/bin/bash的用戶;
[root@Pikachu ~]# grep "bash$" /etc/passwd | cut -d: -f1
root
PIkachu
hadoop
9、找出/etc/passwd文件中的一位數或兩位數;
[root@Pikachu ~]# grep "\<[[:digit:]]\{1,2\}\>" /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
apache:x:48:48:Apache:/usr/share/httpd:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
saslauth:x:994:76:Saslauthd user:/run/saslauthd:/sbin/nologin
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
radvd:x:75:75:radvd user:/:/sbin/nologin
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
oprofile:x:16:16:Special user account to be used by OProfile:/var/lib/oprofile:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
10、顯示/boot/grub/grub.conf中以至少一個空白字符開頭的行;
[root@Pikachu ~]# grep "^[[:space:]]\+" /boot/grub2/grub.cfg
load_env
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
set default="${saved_entry}"
menuentry_id_option="--id"
menuentry_id_option=""
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
set timeout_style=menu
set timeout=5
set timeout=5
source ${prefix}/user.cfg
if [ -n "${GRUB2_PASSWORD}" ]; then
set superusers="root"
export superusers
password_pbkdf2 root ${GRUB2_PASSWORD}
fi
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod xfs
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 --hint='hd0,msdos1' 6b2e77e3-4807-44d4-a573-1384c6450398
else
search --no-floppy --fs-uuid --set=root 6b2e77e3-4807-44d4-a573-1384c6450398
fi
linux16 /vmlinuz-3.10.0-862.14.4.el7.x86_64 root=/dev/mapper/centos-root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=en_US.UTF-8
initrd16 /initramfs-3.10.0-862.14.4.el7.x86_64.img
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod xfs
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 --hint='hd0,msdos1' 6b2e77e3-4807-44d4-a573-1384c6450398
else
search --no-floppy --fs-uuid --set=root 6b2e77e3-4807-44d4-a573-1384c6450398
fi
linux16 /vmlinuz-3.10.0-862.el7.x86_64 root=/dev/mapper/centos-root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=en_US.UTF-8
initrd16 /initramfs-3.10.0-862.el7.x86_64.img
load_video
insmod gzio
insmod part_msdos
insmod xfs
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 --hint='hd0,msdos1' 6b2e77e3-4807-44d4-a573-1384c6450398
else
search --no-floppy --fs-uuid --set=root 6b2e77e3-4807-44d4-a573-1384c6450398
fi
linux16 /vmlinuz-0-rescue-0e35b7e6076043e5aa5f60894ef1010b root=/dev/mapper/centos-root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet
initrd16 /initramfs-0-rescue-0e35b7e6076043e5aa5f60894ef1010b.img
source ${config_directory}/custom.cfg
source $prefix/custom.cfg;
11、顯示/etc/rc.d/rc.sysinit文件中以#開頭,後面跟至少一個空白字符,而後又有至少一個非空白字符的行;
[root@Pikachu ~]# grep "^#[[:space:]]\+[^[:space:]]\+" /etc/rc.d/rc.local
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
12、打出netstat -tan命令執行結果中以‘LISTEN’,後或跟空白字符結尾的行;
[root@Pikachu ~]# netstat -tan | grep "LISTEN[[:space:]]*$"
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN
tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp6 0 0 ::1:25 :::* LISTEN
tcp6 0 0 :::111 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:631 :::* LISTEN
13、添加用戶bash, testbash, basher, nologin (此一個用戶的shell爲/sbin/nologin),而後找出當前系統上其用戶名和默認shell相同的用戶的信息;
[root@Pikachu ~]# useradd bash
[root@Pikachu ~]# useradd testbash
[root@Pikachu ~]# useradd basher
[root@Pikachu ~]# useradd -s /sbin/nologin nologin
[root@Pikachu ~]# grep "\(^[^:]\+\>\).*\1$" /etc/passwd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
bash:x:1005:1005::/home/bash:/bin/bash
nologin:x:1008:1008::/home/nologin:/sbin/nologin