PPP (Point to Point Protocol) is used to connect the Red hat Linux system to

the ISP through the modem. PPP is faster and more efficient. It uses the TCP/IP

network protocol. SLIP(Serial Line Interface Protocol) is also used as the replacement

but it is not as successful as PPP. Most of the ISP's prefer PPP.

Setting up PPP

In order to set up PPP, first a dummy interface has to be set up. When connected

to an ISP, the IP address is assigned dynamically. It will be appropriate to

assign a dummy IP address to our machine, which leads back to the same machine.

It is assigned inside the file "/etc/hosts"

127.0.0.1 localhost localhost.localdomain.

This IP address 127.0.0.1 is always reserved for all the local machines in

a network. After writing to the /etc/hosts file, the following commands has

to be given by logging in as root.

Ifconfig lo 127.0.0.1

Route add 127.0.0.1

Where "lo" is the Localhost and "add" is the address. This

determines the end past of the creating of dummy interface. The proper functioning

of the dummy interface can be determined by the commands "ifconfig lo"

and "ping localhost".

The two components used by PPP on your system are:

1. The demon called ppppd - Controls the use of PPP

2. The driver called High-level Data Link Control (HDLC) - Controls the flow

of information between two machines.

When the Red Hat Linux is installed, PPP usually comes along with it. In case

of its absence, we have to collect them from the Linux web sites, or else they

have to be installed directly from the CD using the "rpm" command.

rpm -ivh /mnt/cdrom/Redhat/RMPS/ppp -2*rpm

As we are connecting our machine to the internet, we have to create a separate

logging in order to prevent the hackers. By writing into the "/etc/passwd"

file,

ppp:*.500:50:ppp account:/tmp:/etc/ppp/pppscript

a user called ppp with the login id 500 is created without a password.

Chat script tells the PPP about the details on the modem and how to use it.

A chat script can be created by

"" ATZ OK ATDT5328835 CONNECT " " ogin: mylogin word: mypassword

Here the script contains 532-8835 as the phone number along with the login and

password.

Then the chat handles the control over to pppd. It can be manually started

by