Tuesday, May 5, 2009
Patch Cord Cable
Straight : B-Core
1 2 3 4 5 6 7 8
OW Ora GW Blue BW G BrownWh Brown
Straight : A-Core
1 2 3 4 5 6 7 8
GW Green OW Blue BW Orange BW Brown
Note:
OW -> Orange White
GW -> Green White
BW -> Blue White
Method:
Nowadays B-B type straight cable are using
A-A type not in field
Cross:
A - B
B - A
Wednesday, April 8, 2009
File Permission
File Permission
File
Owner
Group
Other user
Permission mode
Symbolic
Absolute
Permissions Symbolic absolute
read r 4
write w 2
execute x 1
readwrite rw 6
readexec rx 5
writeexec wx 3
readwriteexec rwx 7
no access - 0
File Permission Structure
1 2 3 4 5 6 7 8 9 10 These are fields
Type of file --> 1
Owner permission --> 2, 3, 4
Group permission --> 5, 6, 7
Other user permission --> 8, 9, 10
Commands
Syntax
#useradd
--> if you want to make a user with desire uid, gid etc
(or) #useradd –u
-G
-C
#groupadd
(or)
# groupadd –g
#passwd
(or)
#passwd –d
Explanation
/etc/group :
If
Backup : x : 502 : secondary users specification
If u create a user with useradd, it will generate 7 fields auto.
Ex: for useradd
#user add –u 1000 –g backup –G print, flag
-d/raj -c “supersuer “ raj
The above line create what our desire user with name of raj
If u create a userid with 500 means, next one is 502
Then it will check to create next one means, It will choose the largest group id & make to add +1
Commands
#id sai --> give gid & uid
#finger sai --> It will show all details about user sai
#user del sai --> remove all details frm /etc/group, shadow & passwd… But
/home/sai & /var files are existing
#user del -r sai --> delete sai from entire file system
#passwd sai--> set password (/etc/shadow)
#passwd –d sai --> remove password ’’
#pwconv --> It updates detail from /etc/passwd to /etc/shadow, /etc/shadow is read-only
#passwd –l sai --> To lock a passwd for sai
#passwd –u sai --> To unlock a passwd for sai
#usermode –s /bin/nologin sai --> to change the shell lever from default one /bin/bash to /bin/nologin. Then sai will not login into system. He blocked
To lock (ie) nologin to all user except root to make file
To create
# touch /etc/nologin
To remove
# rm –rf /etc/nologin
[Note: If you want to protect particular user, go to /etc/passwd file and enter “exclamation mark” at end of that particular user.]
Benefit for Boot loader passwd
If u want to change root’s passwd, you cant enter into linux with single user mode and change it
Steps:
Switch on the system
press ’e’ (i.e.) it shows on the screen
Enter into kernel………. Like ths
But you set bootloader (Grub) passwd, you will not enter inot root’s section directly.
Do it first
#grub –mds-crypt --> This makes encryptions files.
Boot passwd also available (or) grub
OS passwd also available
How to set OS passwd?
It’s set only after the Installed,
Go to #/boot/grub/grub.conf
Enter the OS passwd below the title menu
If you want to set encrypted passwd to grub or OS, you can use
#grub-mds-crypt file & copy the result set to grub
Password=msd-result of crypt
{ Below the splash ing }
Password—mds result of crypt for grub passwd
Linux Basic
Commands
Vi Editor or Emacs Editor (Which is powerful one)
User administration
File permission
Bash configuration
Printer Configuration
Managing process
Find -Methods
Linux File Sysytem Indepth
Net work Clients
USER ADMINISTRATION
Commands
useradd
userdel
user mod
groupadd
groupmod
passwd
pwconv
id
finger
Files
/etc/passwd
/etc/group
/etc/shadow
User Account Information
User id
Login name
Group id (primary and secondary)
Password
Home dir path
Shell
Comment
Thursday, April 2, 2009
Richard Matthew Stallman's Quote
"People said I should accept the world. Bullshit! I don't accept the world."
"I'm always happy when I'm protesting"
"Playfully doing something difficult, whether useful or not, that is hacking"