Modem-Dialup-NT HOW-TO

Al Dev (Alavoor Vasudevan) alavoor[AT]yahoo.com

v1.4, 12 Feb 2002


This document will help you to setup the Modem to do Dial-up Networking with remote server like Windows NT RAS or Linux RAS (Remote Access Server). You can use the Modem to do Dial-Up Networking on Linux very similar to that of MS Windows dialup networking.

1. Introduction

2. Quick Steps to Dialup Networking

3. Remote connection with VNC

4. Related URLs

5. Other Formats of this Document

6. Copyright

7. Appendix A Connecting Linux + PPP < -- > NT + RAS...


1. Introduction

(The latest version of this document is at http://www.milkywaygalaxy.freeservers.com. You may want to check there for changes).

Most of the companies in USA and Europe provide "Remote Access Servers" (RAS), so that their employees can dial-in from remote locations either from home or from field. RAS servers are generally Linux RAS servers or MS Windows NT RAS servers.

Nowadays, Virtual Private Network (VPN) is becoming quite popular because it supports broadband and may eventually replace dial-up networking which is very slow running at 56KB/sec. See the VPN HOWTO and VPN-Masquerade howto and java based MindTerm-SSH-HOWTO.

Configuring a dial-up connection on Linux is about as simple as it is in Windows. We will use PPP.

Definition: PPP ('Point to Point Protocol') is a protocol, that makes it possible to make IP-Links (Internet Protocol) between two computers with a modem.

The operating system Linux has this protocol in the kernel (If you compiled it into the kernel). For a ppp-link you need to start a daemon called pppd.

With PPP you can make a link between two hosts which understand the protocol. A link between a Linux host, acting as client and a Windows NT server, acting as server, is called a (Microsoft term) 'Remote Access Service' (RAS) link.

First, see if your modem is supported by linux. Internal Modems (WinModems) do not work with linux. Some WinModems require special tweaking to make it work in linux.

1.1 Preparations

Check if you have all the needed hardware, software and data and hand:


2. Quick Steps to Dialup Networking

These quick steps will enable you to setup dial-up networking on Linux in just five minutes.

You need the following packages:

You can check with rpm -qa | grep -i wvdial for the installed packages on redhat linux. Use equivalent package commands in case of other distributions like Debian or Slackware.

The steps below are for MS Windows NT RAS server. The NT RAS requires noauth in wvdial file. The Linux RAS may need different settings. In the sample example given below, you should replace username john with the user ID given to you to login into remote RAS server.

  1. Edit the file /etc/wvdial.conf and insert lines like
    [Dialer myconnection]
    Username = john
    Password = passwordofjohn
    Phone = 982 1956
    Area Code = 713
    Inherits = Dialer Defaults
    Stupid mode = 1
    

    Change john with whatever.

  2. Edit /etc/ppp/pap-secrets and insert lines like
    # Secrets for authentication using PAP
    # client        server  secret                  IP addresses
    john            ppp0    passwordofjohn
    john            *       passwordofjohn
    

    Change john with whatever.

  3. Edit /etc/ppp/chap-secrets and insert lines like
    # Secrets for authentication using CHAP
    # client        server  secret                  IP addresses
    john            ppp0    passwordofjohn
    john            *       passwordofjohn
    

    Change john with whatever.

  4. Edit /etc/ppp/options and insert lines like
    lock
    defaultroute
    noipdefault
    idle 1200
    usepeerdns
    proxyarp
    

  5. Create a new file /etc/ppp/ip-up and insert lines like
    #!/bin/bash
     
    # This file /etc/ppp/ip-up should not be modified -- make local changes to
    # /etc/ppp/ip-up.local instead
     
    LOGDEVICE=$6
    REALDEVICE=$1
     
    export PATH=/sbin:/usr/sbin:/bin:/usr/bin
     
    [ -f /etc/sysconfig/network-scripts/ifcfg-${LOGDEVICE} ] && /etc/sysconfig/network-scripts/ifup-post ifcfg-${LOGDEVICE}
     
    [ -x /etc/ppp/ip-up.local ] && /etc/ppp/ip-up.local "$@"
     
    exit 0
    

  6. Create a new file /etc/ppp/ip-up.local and insert lines like
    #!/bin/sh
     
    echo "  "
    echo "Before doing route add......"
    echo "Output from netstat -nr is : "
    netstat -nr
    echo "  "
     
    echo " Doing route add now....  "
    # You should change the lines below and add the networks where 
    # your remote machines are ...
    route add -net 156.15.24.0 netmask 255.255.255.0 dev ppp0
    route add -net 172.28.36.0 netmask 255.255.255.0 dev ppp0
    route add -net 172.28.39.0 netmask 255.255.255.0 dev ppp0
    route add -net 172.28.26.0 netmask 255.255.255.0 dev ppp0
     
    echo "After doing route add......"
    echo "Output from netstat -nr is : "
    netstat -nr
     
    echo "  "
    

    When wvdial is started it automatically starts the pppd which automatically calls this script to add route to your remote networks via the PPP link. See 'man pppd'. In the example above I have to connect to remote networks 156.15.24, 172.28.36, 172.28.39 via the PPP link. You should replace these with your settings. You can also manually add or delete the route after starting the PPP.
    bash$ su - root
    bash# route add -net 172.28.26.0 netmask 255.255.255.0 dev ppp0
    bash# route del -net 172.23.2.0 netmask 255.255.255.0 dev ppp0
    

  7. Create a new file /etc/ppp/ip-down and insert lines like
    #!/bin/bash
     
    # This file /etc/ppp/ip-down should not be modified -- make local changes to
    # /etc/ppp/ip-down.local instead
     
    LOGDEVICE=$6
    REALDEVICE=$1
     
    export PATH=/sbin:/usr/sbin:/bin:/usr/bin
     
    [ -x /etc/ppp/ip-down.local ] && /etc/ppp/ip-down.local "$@"
     
    /etc/sysconfig/network-scripts/ifdown-post ifcfg-${LOGDEVICE}
     
    exit 0
    

  8. Create a new file /etc/ppp/ip-down.local and insert lines like
    #!/bin/sh
     
    echo "  "
    echo "Before doing route delete ......"
    echo "Output from netstat -nr is : "
    netstat -nr
    echo "  "
     
    echo " Doing route delete now....  "
    # Lines below should be same as in ip-up.local but with delete
    route del -net 156.15.24.0 netmask 255.255.255.0 dev ppp0
    route del -net 172.28.36.0 netmask 255.255.255.0 dev ppp0
    route del -net 172.23.2.0 netmask 255.255.255.0 dev ppp0
     
    echo "After doing route delete ......"
    echo "Output from netstat -nr is : "
    netstat -nr
     
    echo "  "
    

    When pppd is stopped it automatically calls this script to clean up whatever ip-up script did. See 'man pppd'.

  9. Edit /etc/ppp/peers/wvdial and insert lines like
    noauth user john
    name wvdial
    

    Change john with whatever.

  10. If you have an external modem, then just before dialing, switch off/on the power to modem to reset it.
    bash$ su - root
    bash# tail -f /var/log/messages
    
    Bring up another xterm shell window and 
    bash$ su - root
    bash# man pppd
    bash# man wvdial
    bash# cd /etc/ppp
    bash# nohup wvdial myconnection &
    bash# tail -f nohup.out
    
    Bring up another xterm shell window and 
    bash$ su - root
    bash# ifconfig -a
    And you should see ppp device listed and up and running.
    bash# netstat -nr
    And you should see ppp device listed along with other interfaces.
    

  11. By this step the pppd should have established the routes to remote networks with ip-up.local script. Also pppd should have created the /etc/ppp/resolv.conf for DNS servers. Now, try connect to remote host and verify connections.
    bash$ su - root
    bash# tail -100 /var/log/messages | less
    bash# cat /etc/ppp/resolv.conf
    bash# ifconfig -a
    bash# netstat -nr
    I looked for route to network 156.15.24.0 (You should see your 
    network as per /etc/ppp/ip-up.local)
    bash# ping 156.15.24.68
    bash# telnet 156.15.24.68
    
    You can also edit /etc/hosts and add these hosts
    156.15.24.64    starship
    172.28.36.131   gemstone
    bash# ping starship
    bash# ping gemstone
    bash# telnet gemstone
    bash# ftp gemstone
    

  12. To stop the PPP :
    bash$ su - root
    bash# killall wvdial
    bash# killall pppd
    bash# man killall
    

  13. Now enable non-root user to do dial-up networking with PPP. Make sure that the user belongs to the groups `uucp' and `dialout'.
    bash$ su - root
    bash# su - someuser
    bash$ id
    uid=501(someuser) gid=501(maingid) groups=501(maingid),503(staroffice),505(staff)
    This shows the groups 'someuser' belongs.
    
    bash$ exit
    bash# usermod --help
    bash# usermod -g maingid -G staroffice,staff,uucp,dialout someuser
    bash# chgrp -R uucp /etc/ppp
    bash# chmod -R ug+r /etc/ppp
    bash# chmod -R o-rwx /etc/ppp
    bash# chmod go-rwx /etc/ppp/*secrets
    bash# chmod u+s /usr/sbin/pppd
    bash# su - someuser
    bash$ id
    This will display groups someuser belongs and you should see uucp.
    bash$ nohup wvdial myconnection &
    bash$ tail -f nohup.out
    

    It is very strongly recommended that you use wvdial as `normal' user, and make sure that the user belongs to the groups `uucp' and `dialout'.

  14. See also the frontend tool for wvdial at X-wvdial.

  15. If you do not have any other interface ethernet cards for Cable modem or DSL modem then you can setup telephone dial-up modem as the default route for all outside conections to internet. Assuming you only have modem connection via POTS (Plain Old Telephone System) you can do -
    bash$ su - root
    bash# man route
    bash# ifconfig -a
    And look for the IP address of the ppp device, and use it below
    bash# route add default gw  IP_of_ppp_device
    For example -
    bash# route add default gw  172.28.36.3
    

2.1 Troubleshooting

In case you have problems:


bash$ su - root
bash# tail -f /var/log/messages
And then start myconnection in /etc/wvdial.conf
bash# wvdial myconnection

bash# ifconfig -a
Should list ppp

bash# netstat -nr
Should list ppp

If you have multiple interfaces, like ethernet cards to DSL or Cable modem,
to check which route is being used, do:
bash# traceroute www.yahoo.com
bash# traceroute remotehostname

2.2 Graphical Tools

Preference should be given the console line commands as in previous section, but some people prefer GUI interface. You can use graphical tools like Linuxconf, KPPP, GnomePPP and many others.

Note: I very strongly recommend using command-line console commands 'wvdial' as demonstrated in previous sections, as they are lot simpler and easy to use.


bash$ su - root
bash# linuxconf &
And select Networking->Client Tasks->Routing & Gateways->Set Other Routes to networks->Add network
. Also select Networking->PPP

bash# rp3 &
bash# rp3-config &


3. Remote connection with VNC

Once you have connection through PPP to remote machines, you can use the VNC to display remote machines on your local display.

Compiling qvwm on Solaris : On Solaris you should install the following packages which you can get from http://sun.freeware.com - xpm, imlib, jpeg, libungif, giflib, libpng, tiff. And you can download the binary package for solaris from http://www.qvwm.org.

Or you can download the qvwm source for solaris from http://www.qvwm.org and compile it using gcc.

Troubleshooting compile: You should put unsigned long before arg in usleep() usleep((unsigned long) 10000)

3.1 Microsoft "MS Outlook" Email from PPP

  1. At office, start VNC server on your Windows NT/2000 desktop.
  2. Connect from home using modem via PPP.
  3. Once the PPP is established, you can start the vncviewer program. Just type /usr/bin/vncviewer.
  4. Enter your office Windows NT/2000 desktop's hostname and vnc password
  5. The entire desktop of your remote office Windows NT/2000 is displayed. Now you can read your MS Outlook email.

4. Related URLs

Linux goodies main site is at http://www.milkywaygalaxy.freeservers.com Mirror sites are at - http://aldev0.webjump.com, angelfire, geocities, virtualave, 50megs, theglobe, NBCi, Terrashare, Fortunecity, Freewebsites, Tripod, Spree, Escalix, Httpcity, Freeservers.


5. Other Formats of this Document

This document is published in 14 different formats namely: DVI, Postscript, Latex, Adobe Acrobat PDF, LyX, GNU-info, HTML, RTF(Rich Text Format), Plain-text, Unix man pages, single HTML file, SGML (Linuxdoc format), SGML (Docbook format), and MS WinHelp format.

This howto document is located at:

You can also find this document at the following mirrors sites:

The document is written using a tool called "SGML-Tools" which can be got from: http://www.sgmltools.org Compiling the source you will get the following commands like:

5.1 Acrobat PDF format

A PDF file can be generated from postscript file using either acrobat distill or Ghostscript. And a postscript file is generated from DVI which in turn is generated from a LaTex file. You can download distill software from http://www.adobe.com and from unix and from windows . Given below is a sample session:


bash$ man sgml2latex
bash$ sgml2latex filename.sgml
bash$ man dvips
bash$ dvips -o filename.ps filename.dvi
bash$ distill filename.ps
bash$ man ghostscript
bash$ man ps2pdf
bash$ ps2pdf input.ps output.pdf
bash$ acroread output.pdf &

Or you can use the Ghostscript command ps2pdf. ps2pdf is a work-alike for nearly all the functionality of Adobe's Acrobat Distiller product: it converts PostScript files to Portable Document Format (PDF) files. ps2pdf is implemented as a very small command script (batch file) that invokes Ghostscript, selecting a special "output device" called pdfwrite. In order to use ps2pdf, the pdfwrite device must be included in the makefile when Ghostscript was compiled; see the documentation on building Ghostscript for details.

5.2 Convert Linuxdoc to Docbook format

This document is written in linuxdoc SGML format. The Docbook SGML format supercedes the linuxdoc format and has a lot more features than linuxdoc. The linuxdoc is very simple and easy to use. To convert linuxdoc SGML file to Docbook SGML use the program ld2db.sh and some Perl scripts. The ld2db output is not 100% clean and you need to use the clean_ld2db.pl Perl script. You may need to manually correct a few lines in the document.

The ld2db.sh is not 100% clean, so you will get some errors when you run it.
        bash$ ld2db.sh file-linuxdoc.sgml db.sgml
        bash$ cleanup.pl db.sgml > db_clean.sgml
        bash$ gvim db_clean.sgml 
        bash$ docbook2html db.sgml

And you may have to manually edit some of the minor errors after running the Perl script. For example you may need to put closing tag < /Para> for each < Listitem>

5.3 Convert to MS WinHelp format

You can convert the SGML howto document to a Microsoft Windows Help file, First convert the sgml to html using:


        bash$ sgml2html xxxxhowto.sgml     (to generate html file)
        bash$ sgml2html -split 0   xxxxhowto.sgml (to generate a single page html file)

Then use the tool HtmlToHlp. You can also use sgml2rtf and then use the RTF files for generating winhelp files.

5.4 Reading various formats

In order to view the document in dvi format, use the xdvi program. The xdvi program is located in tetex-xdvi*.rpm package in Redhat Linux which can be located through ControlPanel | Applications | Publishing | TeX menu buttons. To read a dvi document give the command:

        xdvi -geometry 80x90 howto.dvi
        man xdvi
And resize the window with the mouse. To navigate use Arrow keys, Page Up, Page Down keys, also you can use 'f', 'd', 'u', 'c', 'l', 'r', 'p', 'n' letter keys to move up, down, center, next page, previous page etc. To turn off expert menu press 'x'.

You can read a postscript file using the program 'gv' (ghostview) or 'ghostscript'. The ghostscript program is in the ghostscript*.rpm package and the gv program is in the gv*.rpm package in Redhat Linux which can be located through ControlPanel | Applications | Graphics menu buttons. The gv program is much more user friendly than ghostscript. Also ghostscript and gv are available on other platforms like OS/2, Windows 95 and NT. You can view this document even on those platforms.

To read a postscript document give the command:

                gv howto.ps
                ghostscript howto.ps

You can read an HTML format document using Netscape Navigator, Microsoft Internet explorer, Redhat Baron Web browser or any of the 10 other web browsers.

You can read the latex, LyX output using LyX an X Window front end to LaTex.

5.5 Convert HTML to SGML html2sgml

To convert any HTML document to Linuxdoc SGML use the tool 'html2sgml' from http://www.abc.se/~m9339/prog/html2sgml.html.


6. Copyright

Copyright policy is GNU/GPL as per LDP (Linux Documentation project). LDP is a GNU/GPL project. Additional restrictions are - you must retain the author's name, email address and this copyright notice on all the copies. If you make any changes or additions to this document then you should intimate all the authors of this document.


7. Appendix A Connecting Linux + PPP < -- > NT + RAS...

This section is written by John Newbigin, Email: jn@it.swin.edu.au Below is extract from http://uranus.it.swin.edu.au/~jn/linux/ppp/linuxppp.htm

See also PPP HOWTO