1. Linux Directory structure - description of all standard directories in Linux
2. Standard Linux Security Model
2.1. File permitions
2.2. Users & Groups
2.3. Special file flags
2.4. Special attributes
2.5. Device files
Describing the the Unix file permitions model
/ - how many nodes are connected to this file/dir (not the number of files or dirs in dir)
| / - date & time
| size - \ | / - file name
| | | |
-rw-r--r-- 1 root root 4483445 2005-12-17 00:19 httpd-2.0.55.tar.bz2
| | | | |
owner -/ | | | \ - group owner rwx
group ----/ | \ - owner's username 7 - 0111
others ------/ 6 - 0110
5 - 0101
chmod 755 filename 4 - 0100
3 - 0011
owner | group | others user mask 2 - 0010
rwx | rwx | rwx | mode mode | permitions 1 - 0001
-------|-------|--------|------ ------|------------ 0 - 0000
111 | 101 | 101 | 755 000 | 666
110 | 100 | 100 | 644 022 | 644
111 | 000 | 000 | 700 044 | 622
110 | 000 | 000 | 600 066 | 600
0 - 0000
1 - 0001
2 - 0010
3 - 0011
4 - 0100
5 - 0101
6 - 0110
7 - 0111
How to calculate UMASK:
base 0666 0666 0666 0666 0666 0666 0666 0666
umask 0000 0111 0222 0333 0444 0555 0666 0777
result 0666 0666 0444 0444 0222 0222 0000 0000
T - sticky bit
S - setuid bit
1000 - +t
2000 - g+s
3000 - g+s,+t
4000 - u+s
5000 - u+s,+t
6000 - g+s,u+s
7000 - g+s,u+s,+t
hackman@gamelon:~$ ls -la a
---S--S--T 1 hackman hackman 0 2009-10-20 13:45 a
/etc/passwd
USERNAME:PASSWORD:UID:GID:ADDITIONAL INFO:HOMEFOLDER:SHELL
root:x:0:0:The Administrator:/root:/bin/bash
bin:x:1:1:bin:/bin:
/etc/shadow
/etc/group - since 1992
GROUPNAME:PASSWORD:GROUPID:GROUP USERS
/etc/gshadow
/etc/nsswitch.conf - since 1999
commands:
useradd - add new user
userdel - removes existing user
usermod - modifies user information
passwd - change user passowd
groupadd - add new group
groupdel - removes existing group
groupmod - change group name
groups - show all groups in which you are member
gpasswd - change group password
chsh - chnage user shell
chfn - change user info
chown - change the owner
chgrp - change the group owner
chmod - change file permissions
umask - change the file creation mask
additional chmod:
sticky bit - 1
set gid - 2
set gid & sticky bit - 3
set uid - 4
set uid & sticky bit - 5
set uid & set gid - 6
set uid & set gid & sticky bit - 7
additional file attributes:
lsattr - list file attributes
chattr - change file attributes
A - noatime
a - append only
i - immutable
j - jurnaled (useful only with ext3)
s - secure delete
S - sync to disk
u - undelete (not for ext2 & ext3)
Последна модификация: Tuesday, 20 October 2009, 01:52 PM