Basic Linux Training

Lesson 14: Linux and the Internet

Your PPP Connection
Netscape
Assignments

Your PPP Connection

Although there is a tremendous amount of technical detail to TCP/IP and telecommunications, setting up your connection to the Internet is very simple. The textbook covers SLIP, so we'll discuss PPP here. Since almost all of the class is coming from a DOS/Windows background, I have included some notes about installing Netscape also.

To establish a PPP connection to the Internet through your ISP, you have to login: as root to set up a few scripts:

check your local permissions (to prevent others from logging onto your system while you are connected to your ISP)
```
        /etc/hosts.deny
        ALL:ALL
```

and to allow you to access your own machine

        /etc/hosts.allow
        ALL:127.0.0.1

identify your local network

        /etc/networks
        default 0.0.0.0
        loopnet 127.0.0.0
        ISP dotted quad

identify your machine's name

        /etc/HOSTNAME
        your machine's name

identify your ISP's name and nameserver (dotted quads)

        /etc/resolv.conf
        search name of your ISP
        nameserver dotted quad address of your ISP nameserver

identify your local host

        /etc/hosts
        127.0.0.1 localhost
        0.0.0.0 your machine name

identify your mail server

        /etc/mailname
        mail server

your username and password

        /etc/ppp/pap-secrets
        your username+password

your dialup script and login

        /etc/ppp/chatscript
        TIMEOUT 5
        "" ATZ
        OK ATDT phone number of your ISP
        ABORT "NO CARRIER"
        ABORT BUSY
        ABORT "NO DIALTONE"
        ABORT WAITING
        TIMEOUT 45
        CONNECT ""
        TIMEOUT 5
        NAME user login name
        WORD your password
        IN command line for launching PPP

Curiously, pppd comes pre-installed with Slackware, but not Red Hat. If it's not included with your distribution you can download the tarball ppp-2.2.0g.tar.gz from ftp.pht.com/.3/sunsite/system/network/serial/ppp/

you will also have to edit ppp-on which may be in /usr/sbin or /

        TELEPHONE=1-234-555-6789
        ACCOUNT=
        PASSWORD=
        LOCAL_IP=
        REMOTE_IP=0.0.0.0
        NETMASK=255.255.255.0

You should be able to dial in and get connected. Simply enter

        ~$ ppp-on

then, you can check it using

        ~$ ifconfig or route

To disconnect, type in

        ~$ ppp-off

There are some problems with kernel 2.0.29 so you may want to install patches 30 through 33. You may need to also upgrade to ppp-2.2.0g.tar.gz and update your pppd. Apparently the kernel 2.0.29 does not work with older versions of pppd.

Your ISP may be using a different login process. You'll know if you keep getting disconnected after a few seconds after you dial in. The best way is to dial in manually using minicom or seyon to read the prompts so you can adjust your scripts for what your ISP asks; simply edit your /etc/ppp/ppp-on-dialer file to match what your ISP wants.

If you're having trouble with these scripts, I highly recommend that you download PPPKit-0.7 from http://undertow.csh.rit.edu/atomik or you can get it from ftp://sunsite.unc.edu/pub/Linux/system/network/serial/ppp/PPPKit-0.7.tar.gz to write the scripts for you. This is as simple as it gets setting up ppp.

Netscape

Netscape versions 3.x through 4.03 do not run well with the latest libraries, but there is a possible work around to this problem.

The library that causes the trouble is called libc.so. In the library the memory management functions check whether the freed memory was allocated or not; if not, a bus error occurs.

As with most problems, there is a patch available at ftp://sunsite.unc.edu/pub/Linux/apps/www/browsers/nets-2.0.tar.gz - Netscape fix. This file contains the library you need, (libc.so.5.4.33), and also contains the correct paths and symbolic links. Download this file and unpack it as root in the root (/) directory.

This patch only fixes the memory allocation bug.There is also an especially nasty Java bug. [Playing badly written Java applets can cause your whole system to seize up.]

If you're interest in the Navigator 5 source code (about 8.7 MB), you can download it from http://www.mozilla.org, but remember that you will need gcc installed and upwards of 50 MB free space. Pre-compiled binaries may also be available - caveat emptor

Assignments

Textbook: Running Linux

Chapter 14: TCP/IP and SLIP, p.443-471
- This chapter may be too technical for you to absorb in one reading. Setting up your connection properly can be done without fully understanding all the high tech mechanics and protocols. If you are not using an ethernet, read pages 443 to 451, skip the section on Configuring TCP/IP with Ethernet (pages 451 to 462), then continue reading from SLIP Configuration through the end of the chapter.
Chapter 15: The World Wide Web and Mail, p.479-519
- Again, there is a lot of technical detail you may not need to know immediately.
Bibliography, The Internet, p.601