Linux PPP HOWTO Corwin Light−Williams Joshua Drake Copyright © 2000 by Commandprompt, Inc Copyright © 1997 by Robert Hart This is a LinuxPorts.Com Document for the Linux Documentation Project. Linux PPP HOWTO Table of Contents Chapter 1. How can I help?...............................................................................................................................1 Chapter 2. Introduction......................................................................................................................................2 2.1. Clients and Servers...........................................................................................................................2 2.2. Differences between Linux distributions..........................................................................................3 2.3. PPP configuration tools....................................................................................................................4 Chapter 3. IP Numbers.......................................................................................................................................5 Chapter 4. Aims of this Document....................................................................................................................7 4.1. Setting up a PPP Client.....................................................................................................................7 4.2. Linking two LANs or a LAN to the Internet using PPP...................................................................7 4.3. Using intuitive configuration tools to set up PPP.............................................................................7 4.4. Setting up a PPP server.....................................................................................................................7 4.5. Using PPP over a direct null modem connection..............................................................................7 4.6. This document at present does NOT cover.......................................................................................8 Chapter 5. Software versions covered...............................................................................................................9 Chapter 6. Other Useful/Important Documents............................................................................................10 6.1. Useful Linux Mailing Lists.............................................................................................................10 Chapter 7. Easy Configuration Utilities for PPP...........................................................................................12 7.1. KPPP − The KDE PPP Dialer.........................................................................................................12 7.2. WvDial − A command−line pppd driver........................................................................................20 7.3. rp3 − RedHat PPP dialer.................................................................................................................21 7.4. Linuxconf − Universal (almost) Linux PPP dialer.........................................................................22 Chapter 8. Debugging.......................................................................................................................................26 8.1. I have compiled PPP support into the kernel, but...........................................................................26 8.1.1. Are you booting the right kernel?................................................................................................26 8.1.2. Did you compile ppp kernel support as a module?......................................................................26 8.1.3. Are you using the correct version of PPP for your kernel?.........................................................26 8.1.4. Are you running pppd as root?.....................................................................................................27 8.2. My modem connects but ppp never starts up..................................................................................27 8.3. The syslog says "serial line is not 8 bit clean"................................................................................27 8.3.1. You are not correctly logging into the server..............................................................................27 8.3.2. You are not starting PPP on the server........................................................................................28 8.3.3. The remote PPP process is slow to start......................................................................................28 8.4. Default route not set........................................................................................................................28 8.5. Other Problems...............................................................................................................................29 Chapter 9. Overview of what has to be done to get PPP working as a client..............................................30 9.1. Obtaining/Installing the software....................................................................................................30 9.2. Compiling PPP support into the kernel...........................................................................................30 9.3. Obtaining information from your ISP.............................................................................................31 9.4. Configuring your modem and serial port........................................................................................31 i Linux PPP HOWTO Table of Contents 9.5. Setting up Name to Address Resolution (DNS).............................................................................31 9.6. PPP and root Privileges...................................................................................................................32 9.7. Checking your distribution PPP Files and setting up the PPP Options..........................................32 9.8. If your PPP server uses PAP (Password Authentication Protocol).................................................32 9.9. Connecting to the PPP server by hand............................................................................................33 9.10. Automating your PPP Connection................................................................................................33 9.11. Shutting down the link..................................................................................................................33 9.12. If you have problems....................................................................................................................33 9.13. After the link comes up.................................................................................................................34 9.14. Problems with standard IP services on a Dynamic IP number PPP link......................................34 9.15. Maintaining a permanent connection to the net with pppd...........................................................34 Chapter 10. Configuring your Linux Kernel.................................................................................................35 10.1. Installing the Linux Kernel source................................................................................................35 10.2. Knowing your hardware...............................................................................................................36 10.3. Kernel compilation − the Linux 1.2.13 kernel..............................................................................36 10.4. Kernel compilation − the Linux 1.3.x, 2.0.x, and 2.2.x kernels...................................................37 10.5. Note on PPP−2.x and /proc/net/dev..............................................................................................38 10.6. General kernel config considerations for PPP..............................................................................38 Chapter 11. Getting the Information you need about the PPP server.........................................................40 Chapter 12. Configuring your modem and serial port..................................................................................41 12.1. A note about serial ports and speed capabilities...........................................................................42 12.2. Serial Port Names.........................................................................................................................42 12.3. Configuring your modem..............................................................................................................43 12.4. Note on Serial Flow Control.........................................................................................................44 12.5. Testing your modem for dial out..................................................................................................44 Chapter 13. Setting up Name to Address Resolution (DNS).........................................................................46 13.1. The /etc/resolv.conf file................................................................................................................46 13.2. The /etc/host.conf file...................................................................................................................47 Chapter 14. Using PPP and root privileges....................................................................................................48