Linux PPP HOWTO

Al Longyear, `longyear@netcom.com`

January 8, 1995.

This document contains a list the most Frequently Asked Questions (FAQ) about PPP for Linux (and their answers). It is really not a HOWTO, but is in `classical' Question / Answer form. This is but one of the Linux HOWTO/FAQ documents. You can get the HOWTO's from sunsite.unc.edu:/pub/Linux/doc/HOWTO (this is the `official' place) or via WWW from the Linux Documentation home page . You cannot rely on the HOWTO's being posted to comp.os.linux.answers, as some news feeds have complained about their size.

1. Preface

2. General information

2.1 What is PPP?

2.2 My university (company) does not support PPP. Can I use PPP?

2.3 Where is PPP?

2.4 I just obtained PPP. What do I do with it?

2.5 Where are additional sources of information for PPP?

2.6 Where should I post questions about PPP?

2.7 The PPP software doesn't work. HELP!!!

2.8 Can I use the same local IP address for all of the lines of my PPP

3. Other implementations

3.1 Do you know of a implementation for PPP other than Linux?

3.2 Did you know that there is a program called ``dp`'?

3.3 What RFCs describe the PPP protocol?

4. Compatibility

4.1 Can PPP talk to a SLIP interface?

5. Which is better?

5.1 Which is better? PPP or SLIP?

5.2 Is CHAP or PAP better for authentication?

6. Authentication files

6.1 `/etc/ppp/pap-secrets` file

6.2 `/etc/ppp/chap-secrets` file

7. Construction problems

7.1 I get compile errors when I try to compile the kernel

8. Problems running pppd

8.1 `PPPD` won't run unless you are root

8.2 The `ppp-2.1.2b` package says it needs the 4.6 libraries

8.3 `unable to create pid file: no such file or directory`

8.4 `/etc/ppp/options: no such file or directory`

8.5 `Could not determine local IP address`

8.6 `Could not determine remote IP address`.

8.7 The magic number is always NAKed. It won't connect

8.8 `protocol reject for protocol fffb`

8.9 The PPP software connects but just sends message after message

8.10 I can't connect to the merit network.

9. DIP

9.1 DIP does not have support for PPP's mode

10. Process termination

10.1 Is there a ``dip -k`' for PPP?

10.2 PPP does not hangup the modem when it terminates

11. Data Transfer related issues

11.1 ftp transfers die when I do a `put' but they work

11.2 How do I use XON/XOFF for flow control?

11.3 Modem never seems to connect at a the high rate

11.4 The proxyarp function fails to find the hardware address.

11.5 "`ioctl(TIOCGETD): I/O error`" or "`ioctl(PPPIOCSINPSIG): I/O error`".

12. Routing and other problems

12.1 My route to the remote keeps disappearing!

12.2 I can only reach the remote server.

12.3 I have defaultroute can only reach the remote server.

12.4 I can not ping my local IP address

13. Interactions with other PPP implementations

13.1 `Trumpet` (for `MSDOS`) and the connection simply

13.2 I am using `dp-3.1.2` and can't do anything but ping and

13.3 I can not connect to/with my Windows NT code (a.k.a. 'Daytona')

14. Other messages written to the system log

14.1 `Alarm`

14.2 `Unknown protocol (c025) received!`.

14.3 The connection fails with an `ioctl(TIOCSCTTY)` error.

14.4 "`ioctl(PPPIOCGDEBUG): I/O error`",

14.5 My `ifconfig` has strange output for PPP.

14.6 The file `/proc/net/dev` seems to be empty

15. Network routing issues (using PPP as a `cheap' bridge)

15.1 `Slattach` and `ifconfig` don't work as they do

15.2 I want the route to the network and not the route to the host.

16. Other features and protocols

16.1 What about support for `demand dial'

16.2 What about `filtering'

16.3 How about `IPX`?

16.4 How about NETBIOS?

17. Extraneous

17.1 Do you have a PPP compatible mail reader?

17.2 How about a news reader?