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Robert Hart,

v3.0, 31 March 1997

This document shows how to connect your Linux PC to a PPP server, how to use PPP to link two LANs together and provides one method of setting up your Linux computer as a PPP server.The document also provides help in debugging non-functional PPP connections.


This document is distributed under the terms of the GPL (GNU Public License).


This document will be posted to comp.os.linux.answers as new versions of the document are produced. It is also available in HTML format at:-

Other formats (SGML, ASCII, postscript, DVI) are available from Howtos - other formats.

As carries a very heavy load, please use an appropriate mirror site close to you.


A growing number of people have provided me with assistance in preparing this document. Special thanks go to Al Longyear for the guidance on PPP itself (if there are mistakes here, they are mine not his), Greg Hankins (maintainer of the Linux Howto system)and Debi Tackett (of for many helpful suggestions on style, content order, logic and clarity of explanations.

Finally, to the many people who have contacted me by email offering comments - my thanks. As with all HOWTO authors, the satisfaction of helping is all the payment we receive and it is enough. By writing this HOWTO I am repaying in a small way the debt I - and all other Linux users - owe to the people who write and maintain our OS of choice.

1. Introduction

2. IP Numbers

3. Aims of this Document

4. Software versions covered

5. Other Useful/Important Documents

6. Overview of what has to be done to get PPP working as a client

7. Configuring your Linux Kernel

8. Getting the Information you need about the PPP server

9. Configuring your modem and serial port

10. Setting up Name to Address Resolution (DNS)

11. Using PPP and root privileges

12. Setting up the PPP connection files

13. If your PPP server uses PAP (Password Authentication

14. Setting up the PPP connection manually

15. Automating your connections - Creating the connection scripts

16. Testing your connection script

17. Shutting down the PPP link

18. Debugging

19. Getting Help when totally stuck

20. Common Problems once the link is working

21. Using Internet services with Dynamic IP numbers

22. Linking two networks using PPP

23. After the link comes up - the /etc/ppp/ip-up script

24. Using /etc/ppp/ip-down

25. Routing issues on a LAN

26. Setting up a PPP server

27. Using PPP across a null modem (direct serial) connection

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