readme

经典的ppp程序

This is the README file for ppp-2.4, a package which implements the
Point-to-Point Protocol (PPP) to provide Internet connections over
serial lines.


Introduction.
*************

The Point-to-Point Protocol (PPP) provides a standard way to establish
a network connection over a serial link.  At present, this package
supports IP and the protocols layered above IP, such as TCP and UDP.
The Linux and Solaris ports of this package have optional support for
IPV6; the Linux port of this package also has support for IPX.

This software consists of two parts:

- Kernel code, which establishes a network interface and passes
packets between the serial port, the kernel networking code and the
PPP daemon (pppd).  This code is implemented using STREAMS modules on
SunOS 4.x and Solaris, and as a line discipline under Linux and FreeBSD.

- The PPP daemon (pppd), which negotiates with the peer to establish
the link and sets up the ppp network interface.  Pppd includes support
for authentication, so you can control which other systems may make a
PPP connection and what IP addresses they may use.

The primary platforms supported by this package are Linux and Solaris.
Code for SunOS 4.x is included here but is largely untested.  I have
code for NeXTStep, FreeBSD, SVR4, Tru64 (Digital Unix), AIX and Ultrix
but no active maintainers for these platforms.  Code for all of these
except AIX is included in the ppp-2.3.11 release.


Installation.
*************

The file SETUP contains general information about setting up your
system for using PPP.  There is also a README file for each supported
system, which contains more specific details for installing PPP on
that system.  The supported systems, and the corresponding README
files, are:

	Linux				README.linux
	Solaris 2			README.sol2
	SunOS 4.x			README.sunos4

In each case you start by running the ./configure script.  This works
out which operating system you are using and creates symbolic links to
the appropriate makefiles.  You then run `make' to compile the
user-level code, and (as root) `make install' to install the
user-level programs pppd, chat and pppstats.

N.B. Since 2.3.0, leaving the permitted IP addresses column of the
pap-secrets or chap-secrets file empty means that no addresses are
permitted.  You need to put a "*" in that column to allow the peer to
use any IP address.  (This only applies where the peer is
authenticating itself to you, of course.)


What's new in ppp-2.4.1.
************************

* Pppd can now print out the set of options that are in effect.  The
  new `dump' option causes pppd to print out the option values after
  option parsing is complete.  The `dryrun' option causes pppd to
  print the options and then exit.

* The option parsing code has been fixed so that options in the
  per-tty options file are parsed correctly, and don't override values
  from the command line in most cases.

* The plugin option now looks in /usr/lib/pppd/<pppd-version> (for
  example, /usr/lib/pppd/2.4.1b1) for shared objects for plugins if
  there is no slash in the plugin name.

* When loading a plugin, pppd will now check the version of pppd for
  which the plugin was compiled, and refuse to load it if it is
  different to pppd's version string.  To enable this, the plugin
  source needs to #include "pppd.h" and have a line saying:
	char pppd_version[] = VERSION;

* There is a bug in zlib, discovered by James Carlson, which can cause
  kernel memory corruption if Deflate is used with the lowest setting,
  8.  As a workaround pppd will now insist on using at least 9.

* Pppd should compile on Solaris and SunOS again.

* Pppd should now set the MTU correctly on demand-dialled interfaces.


What was new in ppp-2.4.0.
**************************

* Multilink: this package now allows you to combine multiple serial
  links into one logical link or `bundle', for increased bandwidth and
  reduced latency.  This is currently only supported under the
  Linux-2.3.99pre5 or later kernels.

* All the pppd processes running on a system now write information
  into a common database.  I used the `tdb' code from samba for this.

* New hooks have been added.

For a list of the changes made during the 2.3 series releases of this
package, see the Changes-2.3 file.


Compression methods.
********************

This package supports two packet compression methods: Deflate and
BSD-Compress.  Other compression methods which are in common use
include Predictor, LZS, and MPPC.  These methods are not supported for
two reasons - they are patent-encumbered, and they cause some packets
to expand slightly, which pppd doesn't currently allow for.
BSD-Compress is also patent-encumbered (its inclusion in this package
can be considered a historical anomaly :-) but it doesn't ever expand
packets.  Neither does Deflate, which uses the same algorithm as gzip.


Patents.
********

The BSD-Compress algorithm used for packet compression is the same as
that used in the Unix "compress" command.  It is apparently covered by
U.S. patents 4,814,746 (owned by IBM) and 4,558,302 (owned by Unisys),
and corresponding patents in various other countries (but not
Australia).  If this is of concern, you can build the package without
including BSD-Compress.  To do this, edit net/ppp-comp.h to change the
definition of DO_BSD_COMPRESS to 0.  The bsd-comp.c files are then no
longer needed, so the references to bsd-comp.o may optionally be
removed from the Makefiles.


Contacts.
*********

The comp.protocols.ppp newsgroup is a useful place to get help if you
have trouble getting your ppp connections to work.  Please do not send
me questions of the form "please help me get connected to my ISP" -
I'm sorry, but I simply do not have the time to answer all the
questions like this that I get.

If you find bugs in this package, please report them to the maintainer
for the port for the operating system you are using:

Linux			Paul Mackerras <[e-mail]>
Solaris 2		James Carlson <[e-mail]>
SunOS 4.x		Adi Masputra <[e-mail]>


Copyrights:
***********

All of the code can be freely used and redistributed.  The individual
source files each have their own copyright and permission notice; some
have a BSD-style notice and some are under the GPL.


Distribution:
*************

The primary site for releases of this software is:

	ftp://linuxcare.com.au/pub/ppp/


($Id: README,v 1.24 2001/03/09 00:53:57 paulus Exp $)