11 – ISP Dialup

December 5, 2009 – 10:16 pm

Please note… This information no longer exists at the referenced locations.  This is only a copy of what was available in 2003.

Basic Linux Training™

ISP Dialup

Henry White

Table of Contents

Your PPP Connection

Although there is a tremendous amount of technical detail to the TCP/IP suite of protocols and telecommunications, particularly for a network, setting up your connection to the Internet is relatively simple for home users. Most of the installer programs do an excellent job with this during the initial installation, so you can skim through this if your connection is already working.

If you’re using one of the script writer programs (for example, pppsetup, there are a couple of areas where they do not do such a great job – /etc/resolv.conf almost never will include an alternate search your-ISP line as the RFC states, so if your primary and secondary name servers are busy you’ll be unable to go anywhere.

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

  1. check your local permissions (to prevent others from logging onto your system while you are connected to your ISP) 
            /etc/hosts.deny
        ALL:ALL
  2. and to allow you to access your own machine 
            /etc/hosts.allow
        ALL:127.0.0.1
  3. identify your local network 
            /etc/networks
        default 0.0.0.0
        loopnet 127.0.0.0
        your-ISP dotted-quad
  4. identify your machine’s name in /etc/HOSTNAME 
            your-machine-name
  5. identify your ISP’s name and name server (dotted quads) in /etc/resolv.conf 
            search ISP-hostname
        nameserver ISP-dotted-quad-address-primary-nameserver
        nameserver ISP-dotted-quad-address-secondary-nameserver
  6. identify your local host in /etc/hosts 
            127.0.0.1 localhost
        0.0.0.0 your-machine-name
  7. identify your mail server in /etc/mailname 
            mail-server-hostname
  8. your username and password in /etc/ppp/pap-secrets 
           your-username+password
  9. your dial-up script and login in /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
  10. you may also have to edit ppp-on which should be in /usr/sbin 
            TELEPHONE=[1-234-]555-6789
        ACCOUNT=
        PASSWORD=
        LOCAL_IP=
        REMOTE_IP=0.0.0.0
        NETMASK=255.255.255.0

Most of you will be dialing a local telephone number, so the entry in the script should NOT include the 1 to access long-distance or the area code. Also, note, that hyphens are used here only to separate the area code, exchange, etc. and should not be required in the actual script.

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

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 supply what your ISP wants.

If you’re having trouble with these scripts, I highly recommend that you download the latest version of pppsetup, PPPKit or pppconfig to write the scripts for you. ( ftp://metalab.unc.edu/pub/Linux/system/network/serial/ppp/) These types of programs will prompt you for the variables – username, password, hostname, IP number, etc. – and write the actual scripts for you. It doesn’t get any easier than that ;-) Besides, none of the script writing packages are guaranteed to work for everyone in every situation (some of them make it difficult to go beyond what it has been programmed to handle) – so you’ll end up manually editing the scripts anyhow.

Most of the script-writers will follow a similar procedure. wvdial may give you problems if you are not added to the group with permission to make the connection – so ‘root’ will have to do this for mere mortal users ;-) (This is my preference, BTW, but most home users will want to be able to do this without logging in as ‘root’ to start and stop the connection.) Also there have been some problems with using diald.

Netscape

Some of us who are not into adding the kitchen sink to the browser prefer one of the older versions. In addition, some companies only allow older version for security reasons. (All those neat features also create more ways for the Bad Guys to break in and do nasty things; and, sadly, many sites have badly written Java or javascript that can be a security risk.)

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://metalab.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.]

Netscape Communicator versions 4.04 through 4.08 seem to have gotten progressively more stable, but versions 4.5.x have been a real problem for many. The latest release, 4.76 (in the 4.x series) seems to be the best – but there are STILL memory leaks, etc., and I strongly recommend you disable Java (the problem is not so much the browser as the code itself; that’s a 23 MB download ;-) Another problem is M$ Active-X which appears to be deadly even on Internet Explorer.

The latest version, 6.0, is arguably more stable, yada-yada-yada, Personally, I like it, but it has way too many “features” that I don’t want and have to disable.

If you’re interest in the Navigator 6, you can download the source code from http://www.mozilla.org, but remember that you will need gcc installed and upward of 60-80 MB free space.

(Frankly, you’re much better off going with Mozilla .99 or 1.0 which is in pre-release. This is unencumbered Open Source and where all the ‘action’ is as far as development and bug fixes.)

Assignments

Terms and Concepts:

Define and add these to your glossary:

  • dotted quad
  • host
  • IP address
  • loopback
  • network address
  • subnetwork address
  • broadcast address
  • subnet mask
  • datagram
  • DNS
  • BIND
  • sendmail
  • TCP/IP
  • UDP
  • TCP
  • IP
  • protocol
  • inetd
  • telnetd
  • ftpd
  • named
  • routed
  • gateway
  • packet
  • routing table
  • pon, ppp-on, or ppp-go
  • poff, ppp-off, or ppp-down
  • plog
  • ppp-info
  • ping
  • ifconfig
  • netstat
  • arp
  • rc.inet1 and rc.inet2
  • /etc/fstab
  • /etc/hosts
  • /etc/hosts.allow
  • /etc/hostx.conf
  • /etc/hosts.deny
  • /etc/HOSTNAME
  • /etc/inittab
  • /etc/networks
  • /etc/passwd
  • /etc/resolv.conf
  • /etc/ppp/chatscript
  • /etc/ppp/pap-secrets
  • /etc/rc.d/rc.sysinit
  • /usr/doc/ppp
  • Network File System – NFS
  • Network Information System – NIS
  • gopher
  • finger
  • HTTP
  • URL

Online:

Objective 4

Copyright © 1997-2002 Henry White. All Rights Reserved.
Reproduction or redistribution without prior written consent is strictly prohibited. Address comments and inquiries to info@basiclinux.net.

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