manage chain:
# iptables -N new_chain				// create a chain
# iptables -E new_chain old_chain  		// edit a chain
# iptables -X old_chain				// delete a chain

redirecting packet to a user chain:
# iptables -A INPUT -p icmp -j new_chain

listing rules:
# iptables -L					// list all rules of all tables
# iptables -L -v				// display rules and their counters
# iptables -L -t nat				// display rules for a specific tables
# iptables -L -n --line-numbers			// listing rules with line number for all tables
# iptables -L INPUT -n --line-numbers		// listing rules with line number for specific table

manage rules:
# iptables -A chain				// append rules to the bottom of the chain
# iptables -I chain [rulenum]			// insert in chain as rulenum (default at the top or 1)
# iptables -R chain rulenum			// replace rules with rules specified for the rulnum
# iptables -D chain	rulenum			// delete rules matching rulenum (default 1)
# iptables -D chain				// delete matching rules

change default policy:
# iptables -P chain target			// change policy on chain to target
# iptables -P INPUT DROP			// change INPUT table policy to DROP
# iptables -P OUTPUT DROP			// change OUTPUT chain policy to DROP
# iptables -P FORWARD DROP			// change FORWARD chain policy to DROP

In both Fedora and Ubuntu this task includes two basic steps. These are:

• Enter into your existing hard disk linux system.
• Setup GRUB Boot Loader using GRUB program.

a. Enter into your existing hard disk linux system.

Fedora 7:

In fedora recovering grub is easy task as fedora automatically mount the existing system image to /mnt/sysimage in rescue mode.

1. Insert the fedora installation cd to boot from cd.
2. When the boot menu appear enter the rescue mode. A message will be prompt saying mounting the existing fedora system on /mnt/sysimage, click ok.
3. In rescue mode you will be in a shell
4. Enter the following command
   #chroot /mnt/sysimage
5. Now you are in your existing fedora operating system.

Ubuntu 8.04 LTS:

In ubuntu you will have to mount the existing system image manually.

1. Insert the ubuntu live cd and start a live session from cd.
2. open the terminal window
3. the following command will display currently mounted device or harddisk partitions
   #df -h
4. get the device name for /boot if exists or / (root) partition say /dev/sda9.
5. enter the following command
   #sudo mkdir ubuntu
#sudo mount -t ext3 /dev/sda9 ubuntu
6. If you have separate /usr partition say /dev/sda7 enter the following command too.
   #sudo mount -t ext3 /dev/sda7 ubuntu/usr

7. Enter the following command to mount /proc and /dev and change chroot.
   #sudo mount -t proc none ubuntu/proc
#sudo mount -o bind /dev/ ubuntu/dev
#sudo chroot ubuntu /bin/bash
8. Now you are in your existing ubuntu operating system.

b. Setup GRUB Boot Loader using GRUB program.

In grub you are mainly required to find the boot device and set the root to bood device.

1. Insert the ubuntu live cd and start a live session from cd.
   #grub
2. Find the existing boot device using following command. Which will out put something like (hd0,0) or (hd0,5) say (hdX,Y).
   #grub> find /boot/grub/stage1
3. Use the above output in the following two commands.
   #grub> root (hdX,Y)
#grub> setup (hdX)
#grub> quit
4. if everything is ok then you are done. just reboot the system.

This article is completely based on my current experience and I am still a newbie in linux environment. so there may have sevaral other options to do the same task.

Here is a single command what can solve the problem if you have internet connection.


# yum -y install gstreamer*


This command will automatically find, download and install the GStreamer mp3 codec for you. Then you can enjoy the mp3 song with your favorite music player.

You can download xmms one of the popular mp3 player on your fedora system. It is a Winamp alternative to linux. To install this software enter the following command.


# yum -y install xmms*


After installing xmms you will find the menu Application -> Sound & Video -> Audio Player to launch the xmms player.

After a fresh fedora installation I enter the following command in the shell. This command creates a wvdial configuration file for my modem.

# wvdialconf /etc/wvdial.conf

Now I need to modify some contents of wvdial.conf file. To do so I open the /etc/wvdial.conf using VI or other text editor. And replace the content of the file with the following text and save it.

[Dialer Defaults]
Modem = /dev/ttyACM0
Baud = 460800
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
ISDN = 0
Modem Type = USB Modem
Phone = *99#
Username = A
Password = B
Stupid Mode = 1

I make sure to set username = A, Password=B and Stupid Mode = 1 and do not modify the line

Modem = .....

as this is my device name (this line can very with your phone set). Now whenever I need to connect to internet I just enter the following command to the shell.

# wvdial

Thats all. Same way you can turn your mobile set to internet from fedora with no or little modification.