I
shall explain how to setup PPP on your Linux machine, so that
you can connect to the Internet using an external modem and a
Dialup connection. This article explains the setup for the superuser
alone (Not normal users).
Note that if you have KDE installed and have installed Kppp along
with that, then configuring Kppp and getting connected to the
net is much simpler and better than following the procedure given
below. Article No. 14 explains configuration
of Kppp.
My Setup :
- My external modem (56kbps) is connected to the Serial Port
: ttyS1 (This is COM2 Port under Windows)
- My ISP (Internet Service Provider) servers send me the following
strings for logging in whenever I connect to their servers,
"Login" & "Password".
These exact strings need to be known since they have to be entered
in the scripts later on.
Other ISP's may send strings such as "User" and "Pass"
or something else. Please note down the strings that you receive
when you connect to your ISP. If needed contact your ISP's helpdesk.
- Every ISP has generally 2 DNS entries. Actually one is enough
but the other one is for backup. This differs for each ISP.
For my ISP the DNS entries are '202.68.128.66' and '202.68.128.67'.
You have find out your ISP's DNS addresses. My service provider
is named powersurfer.net (This exact name is also required to
be entered in one configuration file).
Procedure :
- Copy
the 2 files ppp-on & ppp-off from the /usr/doc/ppp2.3.10/scripts
(exact directory depends on the installation & distribution
on your system) to the folder /usr/bin
You would have to execute these files whenever you want to connect
and disconnect from the Internet once the setup is complete.
Hence these scripts should have executable rights.
- Edit
the ppp-on script that you have just copied and make the following
changes
Change the telephone no. , username and password to your
username, password and your ISP telephone no.
- Copy
the file ppp-on-dialer file from the /usr/doc/ppp2.3.10/scripts
to the folder /etc/ppp
Edit this file to make the following changes
- Change the connection strings to "ogin" and
"assword" (These should be the strings that
your ISP sends you when you connect to your ISP, excluding the
first letters in both these strings)
- Change the timeout period (Start of dialing to establishing
of final connection) to a sensible value depending on your experience.
I have set it to 120 seconds which is substantially more
than what is required.
- Add an extra line after the existing ATZ command. This is
to mute the modem once the connection has been made. Else you
will hear the signal transfer noises continuously as long as
you are connected. (Atleast I heard the sound on mine)
- Towards the end of the script make a change as follows.. enter
your modem port and max speed in the parameters to the chat
script. For me it is as follows
/dev/ttyS1 115200
- Now
edit the /etc/resolv.conf file to show the following
search powersurfer.net
nameserver 202.68.128.66
nameserver 202.68.128.67
These lines totally depend on your ISP, so please fill it
accordingly.
- Now
the last step is to edit the /etc/ppp/options file and
add the following lines. These settings are used whenever a
net connection is established on your machine. If you want to
know the meaning of each line you can refer to the PPP-How To
documentation. There is a sample script with a description for
each of these values. I have only selected those values that
would be necessary for a normal dial up Internet connection.
These should suffice for most dialup users.
-detach
/dev/ttyS1
lock
crtscts
defaultroute
asyncmap 0
mtu 1500
Note : This article explains the settings that should
be enough for you to connect to the Internet, through the superuser
account. For accessing the Internet from user accounts, a few
more settings are required. I shall explain those in another
article. Though I have heard of a few experiences where even
a normal user types 'su' in a shell window and changes to the
superuser mode (this is for home machines where you are both
the superuser and the normal user). Once you changed to superuser
mode, you might be able to execute ppp-on and ppp-off scripts.
This hasn't really worked at my place, but I have heard quite
a few people doing this. I prefer using kppp to do all the work
for me. Refer to Article No. 14 to read
about using kppp for connecting to the Internet.
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