Modem-Dialup-NT HOW-TO

Al Dev (Alavoor Vasudevan) alavoor[AT]

v1.7, 22 June 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. Dial-up ISP Internet Connection

3. Quick Steps to Dialup Networking

4. Remote connection with VNC

5. Setup RAS server

6. Related URLs

7. Other Formats of this Document

8. Copyright

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

1. Introduction

(The latest version of this document is at 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) may work with Linux because they need extra software drivers to make it work with Linux. Test your WinModem to see if it works under 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. Dial-up ISP Internet Connection

Follow these steps to connect to your ISP via dial-up modem:

After doing the above steps, you would have connected to internet. To test do:
bash$ ping
PING from : 56(84) bytes of data.
64 bytes from ( icmp_seq=0 ttl=58 time=236.931 msec
64 bytes from ( icmp_seq=1 ttl=58 time=229.074 msec

bash$ ping

bash$ su - root
# ifconfig
lo        Link encap:Local Loopback
          inet addr:  Mask:
ppp0      Link encap:Point-to-Point Protocol
          inet addr:  P-t-P:  Mask:

# netstat -nr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface UH       40 0          0 ppp0       U        40 0          0 lo         UG       40 0          0 ppp0

You will see the listing like above. If you are not able to do 'ping' or 'ping' then there is some trouble. See the next section 'Troubleshooting'

2.1 Troubleshooting ISP Connection

If you are getting the connection and getting the local IP address and Remote IP address from KPPP dialer but you are not able to do ping on a remote host like 'ping' then do:

bash$ su - root
# ifconfig

See the listing above and temporarily disable other interfaces like eth0, eth1
# ifconfig eth0 down
# ifconfig eth1 down
# ifconfig eth2 down

# ifconfig
This should list only ppp0 and lo

Once other interfaces like eth0, eth1, eth2 are disabled, now disconnect and reconnect with KPPP dialer. After the connection to internet is successful, you can re-enable other interfaces as below:
bash$ ping
If connection is okay, then do:
bash$ su - root
# ifconfig eth0 up
# ifconfig eth1 up
# ifconfig eth2 up
# ifconfig

If you still have problems then refer to the KPPP user guides and FAQs as below:

$ rpm -ql kdenetwork-ppp
$ cd /usr/share/doc/HTML/en/kppp
$ docbook2html kppp-faq.docbook 1> kppp-faq.html
$ docbook2html index.docbook 1> index.html

3. 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
    idle 1200

  5. Create a new file /etc/ppp/ip-up and insert lines like
    # This file /etc/ppp/ip-up should not be modified -- make local changes to
    # /etc/ppp/ip-up.local instead
    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
    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 netmask dev ppp0
    route add -net netmask dev ppp0
    route add -net netmask dev ppp0
    route add -net netmask 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 netmask dev ppp0
    bash# route del -net netmask dev ppp0

  7. Create a new file /etc/ppp/ip-down and insert lines like
    # This file /etc/ppp/ip-down should not be modified -- make local changes to
    # /etc/ppp/ip-down.local instead
    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
    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 netmask dev ppp0
    route del -net netmask dev ppp0
    route del -net netmask 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 (You should see your 
    network as per /etc/ppp/ip-up.local)
    bash# ping
    bash# telnet
    You can also edit /etc/hosts and add these hosts    starship   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

3.1 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
bash# traceroute remotehostname

3.2 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 &

4. 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 - xpm, imlib, jpeg, libungif, giflib, libpng, tiff. And you can download the binary package for solaris from

Or you can download the qvwm source for solaris from and compile it using gcc.

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

4.1 Microsoft "MS Outlook" Email from PPP

Method 1 :

  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.

Method 2 :

Method 3 : Web based

5. Setup RAS server

For details on RAS please see RAS Buyer's Guide and the RAS product Cyclades PR4000

A Remote Access Server (RAS) is a network box that connects remote dialup clients to a Local Area Network (LAN. RAS are used by Internet Service Providers (ISP) and Corporate Network Managers to allow home users, small offices, and telecommuters to connect to the Internet or the corporate LAN from remote sites using analog phone lines or ISDN lines.

Since the mid-90's, with the popularization of the Internet, the demand for dialup remote access has been growing exponentially. Until faster options are broadly available, analog phone lines and ISDN lines are the more common media to remotely connect personal computers or home offices to the LAN or to the Internet.

A RAS is a box that attaches to the LAN at the central site and provides connection to dialup lines. It allows remote clients to access the LAN (and possibly the Internet) by using modems or ISDN terminal adapters.

In the past, RS-232 Terminal Servers were used to provide remote access. A server-based or stand-alone box would attach to the LAN and provide multiple RS-232 serial interfaces. Those serial ports were connected to a modem bank, which on its turn, connected to the analog phone lines coming into the building.

With the crescent demand, the number of required phone lines started to grow to a point where it was impractical to increase their number at the central site. The phone company, instead of delivering individual phone lines to you, bundle 23 or 30 channels in one T1 or E1 ISDN-PRI line.

Typically, a RAS will have one or more Ethernet ports for connection to the LAN and one or more T1/E1/ISDN-PRI ports for the incoming calls (a T1/ISDN-PRI line is equivalent to 23 phone lines, while an E1/ISDN-PRI line is equivalent to 30 phone lines).

A RAS will typically have internal digital modems and will be able to terminate both analog and digital calls and connect to remote clients using Point-to-Point (PPP) protocol.

5.1 Stand-alone or Server-Based ?

Traditionally, RAS are stand-alone, integrated and self-contained boxes running an Internetworking Operating System on a proprietary hardware specifically designed for Remote Access. They connect to the LAN and to the income dialup lines and all you need to do is to configure them properly to get them working.

But there is also the possibility of building a RAS using standard server hardware (usually a PC) with a Networking Operating System (typically, Linux or Windows). The user installs PCI RAS adapter (with digital modems and ISDN-PRI interfaces) in a PC server, install the OS and the proper device drivers and configure the system to work as a Remote Access Server.

So, maybe the first question you face when selecting a RAS solution is this: Stand-alone or server-based?

In general, stand-alone solutions are better for the average user because of the following factors:

Integration: The RAS solution is complete and there is no need for software or hardware integration. That eliminates the possibility of hardware and software incompatibilities and installation problems and gives you a single point of contact for technical support and problem solving.

Reliability: Stand-alone solutions run on hardware and software that was specifically designed for remote access. They are more integrated, more compact, dissipate less power, and, because of that, are more reliable than a solution based on general-purpose components.

Cost: Usually, commodity PC hardware and open source software tend to drive costs down, making server-based solutions attractive for technical users who already have the PC and are willing to face the potential problems of integrating the solution from standard components. But, the PCI adapters for RAS available in the market today still carry a price tag that makes it difficult to justify a server-based solution.

6. Related URLs

Linux goodies main site is at and secondary site at Mirror sites are at - angelfire, geocities, virtualave, Fortunecity, Freewebsites, Tripod, 101xs, 50megs,

7. 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: Compiling the source you will get the following commands like:

7.1 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 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.dvi
bash$ distill
bash$ man ghostscript
bash$ man ps2pdf
bash$ ps2pdf 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.

7.2 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 and some Perl scripts. The ld2db output is not 100% clean and you need to use the Perl script. You may need to manually correct a few lines in the document.

The is not 100% clean, so you will get some errors when you run it.
        bash$ file-linuxdoc.sgml db.sgml
        bash$ 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>

7.3 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.

7.4 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:


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.

7.5 Convert HTML to SGML html2sgml

To convert any HTML document to Linuxdoc SGML use the tool 'html2sgml' from

8. 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.

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

This section is written by John Newbigin, Email: Below is extract from

See also PPP HOWTO