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Linux and the Internet

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PCQ Bureau
New Update

In March ''96, 50,000 people across India received Linux on

their PC Quest CD-ROMs. The amount of mail I have received about it, is frankly, amazing.

The most common questions include How do I connect to the Internet with Linux? or

"How do I set up a web server using Linux?" This month, I am going to address

both issues, because they go hand in hand.






A Little Background


Linux needs no introduction, not after PC Quest March ''96. However, let me reiterate a few
points here:


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  • Linux comes to you "Internet ready". All the

    required tools are built in and ready to be used. All you need is to set it up, change a

    few parameters here and there, and get up and going.
  • For space reasons, we couldn''t put the complete Linux

    Slackware CD-ROM onto the PC Quest CD-ROM. One of the modules omitted was the NCSA HTTPD

    web server, used by virtually every Linux web server in the world. This has now been

    rectified: you can download it from PCQ Online, CiX (080-3341137) or the Internet.
  • You can set up a Telnet/FTP/Web/E-Mail server with the

    software we supplied, and provided you have a TCP/IP account (PPP/SLIP), you can get your

    server up and running, and accessible, virtually instantaneously, making this a perfect

    solution for a small- to medium-sized business.



    With that out of the way, let''s get the show on the road.
    border="1" align="right" width="50%"> !/usr/sbin/dip



    main:


    get $mtu 1500


    Ip number of the slip router


    Used for the point to point type connection


    get $remote xxx.xxx.xx.x


    Set the desired serial port and speed.


    Remember that Com1 is cua0 and Com2 is cua1


    port cua1


    speed 38400


    parity N


    databits 8


    stopbits 1


    Reset the modem and terminal line.


    flush


    send \r\n\r\n


    Initialization for the modem


    send ATZ\r


    wait OK 2


    send AT&c1&d2&n0x1s10=200s7=90\r


    wait OK 2


    if $errlvl != 0 goto error


    Dial our PPP server from local phone


    Change xxxxxxx to your local dialup number


    send atdtxxxxxxx\r


    wait CONNECT 90


    if $errlvl != 0 goto error


    login:


    We are connected. Login to the system.


    wait username: 10


    if $errlvl != 0 goto error


    REPLACE uuuuuuuu with your login name.


    send uuuuuuuu\r


    wait password: 20


    if $errlvl != 0 goto error


    REPLACE pppppppp with your password.


    send pppppppp\r


    Now wait for the router prompt...


    wait > 30


    send ppp\r


    Now we wait for the assigned IP addresses.


    First comes the remote IP address (of the router)


    wait is 10


    get $rmtip remote


    if $errlvl != 0 goto error


    and now we get our IP address....


    wait is 10


    get $locip remote


    if $errlvl != 0 goto error


    done:


    That''s it! Now let’s make sure that IP packets are sent by default


    to this new connection (which is called ppp0, by the way)


    default


    The following let’s you know what’s happening


    print PPP to $remote with address $local


    print Run ping $remote to check the connection.


    And now switch into PPP mode and start communicating


    mode PPP


    goto exit


    error:


    print PPP to $remote failed.


    exit:


    End of script




























































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    Making Linux Net-Ready








    Nothing to it. If you have installed Linux according to my instructions in the March issue
    (or check my web page at http://pobox.com/~achitnis), and installed TCP/IP along with it

    (remember, I asked you to do that), then you are almost set. Just to make sure, log in as

    root and run the command ping localhost which should give you a stream of ping results

    (stop them with Ctrl+C).






    Run the command netconfig. This will ask you a few questions (you may have gone through
    this before, but let''s do it again), answer them as follows:



    When asked for Hostname, enter a name of your choice.

    Remember, unless you actually register your hostname, this name has no meaning. My machine

    is known as cybercom. And remember to stay in lower-case.

    You will be asked about your domain. I use iisc.ernet.in,

    you would use giasxx01.vsnl.net.in (where "xx" is your city code).

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    When asked about "Loopback only", answer NO.

    You will be asked for an IP address. You do not have a real

    address at this time, so use 192.0.1.1.



    At the question of Gateway, enter the same address as above.

    Next you will be asked for a Netmask--enter 255.255.255.0.

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    You will now be asked for a Name Server--enter 202.54.1.30

    if you are on VSNL (202.54.1.81 for Delhi users), or 144.16.11.1 if you are on ERnet.

    That’s it for the moment. A warning though, if

    you’ve created entries in the file /etc/hosts, backup this file before you run

    netconfig, because the file will be deleted.

    Shut down Linux and reboot, then check whether you can ping

    your host by name (for example, I would run ping cybercom.iisc.ernet.in). If you get back

    ping results, you are ready to move.

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    Now use your communication program (minicom) to connect to

    your TCP/IP dialup number. Log in, and at the router prompt (e.g. giasro04>) type

    “ppp” and press . Make sure that your get a message telling you

    what the remote IP address is and what your address is. The values themselves are not

    important, since they may change with every call. I just want you to be sure that you get

    such a message. After you get it, you can hang up, and proceed with the installation.

    Now change to the /etc directory, and create the following

    script file. You can use VI for this if you are comfortable with it, else use the

    "joe" editor, which is pretty much WordStar-like.

    You have to change a few settings here. One of them is your

    COM port (by default, it is set to "cua02", change it to "cua0"

    (cua-zero) for COM1 and "cua1" for COM2. Unless you have a 16550 serial port,

    change the 38400 to 19200.

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    Change the phone number in the right place to the TCP/IP

    dialup number for your area, and also change the username and password. Save this file as

    /etc/ppp.dip. You can also pick up this file from href="http://ece.iisc.ernet.in/monster/library/index.html">http://ece.iisc.ernet.in/monster/library/index.html.

    The Dialup Script






    OK, now that we have the script installed, all you have to do is run it with the
    "dip" program, which you do by running the command:









    dip /etc/ppp.dip







    If all goes well, you should get a message that you are connected and what your IP
    addresses are. It will also ask you to run the "ping" command with the server IP

    address to make sure that you are indeed connected. Doing so should give you a stream of

    ping results--you can cancel this with ctrl+C.






    Checking Out Your IP Connection





    Once you have the IP connection up and running, you can try a few things. The first one
    you could try is to use the "telnet" command. If you are connected to VSNL, try

    the command telnet giasXX01.vsnl.net.in where XX

    is your city code ("dl" for Delhi, “bm” for Mumbai, etc.). In a few

    seconds, you should be connected and asked for your login name. Enter your login name and

    password and you have access to your VSNL Shell account.






    If this does not happen, you may have goofed with the DNS (Domain Name Server)
    configuration. Use your editor to edit the file /etc/resolv.conf, and make sure that your

    proper DNS addresses are show there. They should look something like this:






    domain vsnl.net.in


    nameserver 202.54.1.30


    nameserver 202.54.1.18









    If this is not the case, edit the file until it looks like the example above. Save the
    file, then try the telnet command again.






    Once you have things working, try an FTP (e.g. ftp sunsite.unc.edu), this should also
    work.



    Now for something more thrilling. If you have another phone line, call up a friend who has
    an Internet account, and ask him to telnet to your IP address (that''s what is reported to

    you when you connected). Make sure you have created an account for your friend--use the

    "adduser" command for this. He will receive a login prompt, where he gives the

    user id and password you have given him.



    That''s it! He is logged into your system. In the same fashion, he can also FTP to your
    system to send and receive files, and he can also "talk" to you (use the

    “talk” command for this. You can find out who is logged in and doing what with

    the "w" command. To disconnect the PPP connection, run the command "dip

    -k". Make sure that everyone is logged off before you do this.






    Logging Off





    Right, now that we know how to create an IP connection to your Internet provider, we need
    to look at more things, like how to access the World Wide Web, how to send and receive

    e-mail, how to set up a Web server of your own, how to set up an FTP site, etc. That''s the

    subject of discussion over the next few months, so stay tuned.

















    Cheerio!



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