Install and Configure Telnet : Fedora

STEP 1:Install Telnet package

yum install telnet-server
yum install xinetd

STEP 2:
Edit the following and find the line for disable and change it from the value "yes" to "no".

# vim /etc/xinetd.d/telnet

STEP 3:
Restart the xinetd deamon

STEP 4:
Inorder to configure Telnet for root logins

Simply edit the file /etc/securetty and add the following to the end of the file:

pts/0
pts/1
pts/2
pts/3
pts/4
pts/5
pts/6
pts/7
pts/8
pts/9
This will allow up to 10 telnet sessions to the server as root

Command to search package name in Linux

Ubuntu:

#apt-cache search package name

Fedora:

#yum list package name

How to unmount while device is busy

Sometimes You might get the following error messages while unmounting
# umount /dev/sda2/
umount: /dev/sda2:device is busy
Try the below command
# fuser -m /dev/sda2
It will show the process id which is causing it
If you get the process id then you can umount!!!!!!

Fedora:How to restore deleted desktop panel

STEP 1:Make a directory
[antony@localhost ~]$ mkdir bak
STEP 2:Move the following files
[antony@localhost ~]$ mv {.gnome*,.gconf*} bak/
STEP 3:Reboot

Enable root login in GUI Fedora

STEP 1:Open the terminal and edit
vim /etc/pam.d/gdm
Comment the following line #auth required pam_succeed_if.so user != root quiet
STEP 2: Also Edit /etc/pam.d/gdm-password
Comment the following line #auth required pam_succeed_if.so user != root quiet
Done...

Disabling iptables in LINUX

For Fedora,Try the following commands
#service iptables save
# service iptables stop
# chkconfig iptables off
For other Linux distributions
# iptables -F
# iptables -X
# iptables -t nat -F
# iptables -t nat -X
# iptables -t mangle -F
# iptables -t mangle -X
# iptables -P INPUT ACCEPT
# iptables -P OUTPUT ACCEPT

Compiling Linux Kernel:Ubuntu

STEP 1: Download latest kernel from http://kernel.org
STEP 2:Extract the downloaded tar file
#tar -xvf linux-2.6.XXXX -C /usr/src#cd /usr/src
STEP 3:Configure Kernel
Make sure development tools "gcc compiler " got installed
#apt-get install gcc
Now type the following command and we can select different options as per our need#make menuconfig
STEP 4:Compilation of kernel
Initially create a compressed kernel image,
#make
Now start compiling to kernel modules
#make modules
Install kernel modules
#make modules_install
STEP 5:Install Kernel
#make install
The above command will install three files into /boot directory
->System.map-2.6.xx
->config-2.6.xx
->vmlinuz-2.6.xx
STEP 6:Creating initrd image
Create using following commands
# cd /boot# mkinitrd -o initrd.img-2.6.xx 2.6.xx
STEP 7:Modify Grub configuration file - /boot/grub/menu.lst
STEP 8:Update the grub
# update-grub
STEP 9:Reboot