DP - General Information

Overview

This software was developed to provide dialup on demand PPP over high speed modems. In many situations, leased lines are used to provide TCP/IP links over significant distances. With the advent of V.32bis (and later V.34) modems, and with this software, another alternative exists. It appears to the application that the modems remain connected all the time (like a leased line). In reality, however, they disconnect whenever there is no traffic. When a packet to be transmitted arrives at the interface, and the modems are not connected, a connection is made and the packets begin to flow again.

Target Audience

This file contains information for those intending to install and use dp (Dialup PPP), and is not aimed at teaching you about TCP/IP networking, although subjects which may be new to you such as routing and nameservers will be mentioned. This is a summary

Credits

The base for this software is several other free packages that have been modified to support this purpose. The dialup code came from the BBN Dialup Slip. The PPP program is from Carnegie Mellon University. The kernel PPP streams driver originally came from Brad K. Clements. Since it now bears such little resemblence to his work, he has relinquished all copyrights. The TCP/IP header compression support came from Van Jacobson from the University of California. Kirk Smith at Purdue University assembled all these pieces, made them all work together, and added a number of features beyond the original software.

The bulk of the work has been done at Purdue University by Kirk Smith <ks@acn.purdue.edu> and has been supported by the Purdue Agricultural Computer Network. The Purdue ACN is responsible for networking 98 remote computers to the campus internet.

Peter Galbavy of Micromuse Ltd. <Peter.Galbavy@micromuse.co.uk> has provided invaluable help in several areas. Among these, were the loadable module support, integration of newer PPP revisions, significant work on this document, and much testing and several bug fixes.

Ignatios Souvatzis <ignatios@cs.uni-bonn.de> has offered a great deal of assistance in testing loadable modules and testing beta releases, providing many fixes.

Jeff Schwab <jrs@ecn.purdue.edu> has provided updates to the PPP code to bring the software in line with current revisions of the PPP standard.

Mark Seiden <mis@seiden.com> has edited this document and greatly improved the readability.

Jim Thompson <jim@tadpole.com> has provided many fixes to the kernel modules and the DP package in general.

Frank D. Cringle <fdc@cliwe.ping.de> has provided many fixes to the lock management in the kernel modules as well as providing updates for the correct operation of rfc1332 Van Jacobsen Header Compression negotiation.

Marc Boucher <marc@CAM.ORG>integrated SLIP support, support for terminal server modems, and sync support. Also, Marc has been a great help in tracking down numerous bug fixes.

Tim Rylance <tkr@puffball.demon.co.uk> integrated a number of pieces of the Solaris 1.X software into the Solaris 2.X version to merge the source trees together for the 4.0 release.

Release History

Major Versions

dp-2 supports Solaris 1.X (SunOS4.X)
dp-3 supports Solaris 2.X (SunOS5.X)
dp-4 supports both Solaris 1.X (SunOS4.X) and Solaris 2.X (SunOS5.X).

Since the introduction of dp-4, the older releases are obsolete.

dp-4.0beta1

Solaris 1 support is now merged in.
No more pesky message at boot time about IFF_POINTOPOINT not set (Sol2).
Not setting ACCESS file in conf file will not cause core dump.
Terminal server modems now supported.
Running over pseudo tty now works reliably.
PPP sync module now available.
SLIP now supported.
Snoop and tcpdump now supported in Solaris 2 as well as Solaris 1.
Most C code is ANSI compatible
Many compiler warnings fixed.
Silly interface addresses flagged.

dp-3.1.4:

Eliminated unecessary error messages on dropped lines.
Fixed bug in dp device driver which could cause a kernel crash in dp_activity().
The vast majority of the updates in dp-3.1.4 are due to the work of Tim Rylance . Thanks Tim.
PPP is now based on ppp-2.1.2, whereas dp-3.1.3 and dp-2.3.2 are based on ppp-1.3 or 1.4.
Advantages of the new version include
- working CHAP and PAP authentication (see newdoc/Authentication)
- negotiation automaton conforms to the current PPP RFCs and seems to have fewer convergence problems
- much better LOG_LEVEL=3 tracing makes negotiation problems much easier to diagnose
I have tested it on both Solaris 2 and SunOS 4 against
- Morningstar (Demon Internet)
- Ascend (BTnet, using CHAP authentication)
- ppp-2.1.2 (using CHAP and PAP authentication)

dp-3.1.3

New PPP option "dynamic" should allow dynamic addresses.
Comments are allowed in /etc/dp/hostnames
Static routes can be placed in /etc/dp/routes
PPP talks to rfc1332 PPP's by default
Support for pre1332 PPP's tested
PPP options -vjcomp and vj-max-slots now available
Bugs in VJ compression now fixed
Very Short IP packets not dropped on input
Several rare panics fixed in dp driver
dpd works with more than 50 interfaces by increasing the limit of open files
MAGMA serial port speed mapping supported.
US Robotics V.everything modem tested (modem/usr.com script/usr-dial)

dp-3.1.2

Three bugs fixed in sys/dp.c that would cause kernel panics
- restarted dpd could cause message buffers to be freed twice, leading to Data Fault
- panic on input when messages are processed after I_UNLINK, causing Data Fault in dplrput().
- panic when incoming and outgoing calls happen simultaneously and mutex_exit got called twice from dp_state().
callwait timeout was increased in access files
t3000-dial and telebit.com files were updated to be compatible with FlexFax
The daily cron script was updated a bit
Refuses to accept loopback addresses for interfaces
recv and use can have more arguments in dial scripts
Central Data 115.1 and 230.2 support added
Uucp locking locks both incoming and outgoing devices

dp-3.1

/var/spool/locks handled better for interface to ttymon
strtok_r function provided for older OS (Solaris 2.0 & 2.1)
Two calls to alloca changed to malloc in ppp/main.c
New access file format
Does not drop routes in Solaris 2.2
Should work for x86 Solaris
Dptrace works
Alternate phone numbers can be listed for busy conditions
ppp does not core dump due to freeing non-malloced memory
now supports PRE_AUX, POST_AUX, and FAIL_AUX scripts
Lots of little fixes

Supported Platforms

dp-4.0 runs on all versions of Solaris available as of July 28, 1995. It is known to run on SPARC, x86, and Sun3 hardware. If you have problems with specific hardware/software configurations, please relay the fixes to Kirk Smith (ks@acn.purdue.edu)

Commercial Software

Companies sell products that do things similar to this. I believe that this software incorporates some unique features and has value in itself. However, if you want a supported product, you might want to shop around.

Morning Star Technologies is one company that I know of. Try sending mail to marketing@morningstar.com for more information. From what I can tell, they have a top notch product and top notch support.

Sun provides PPP bundled with Solaris 2.3 or later. This product is somewhat limited and has some problems, but continues to improve with each release.

Mailing List

A mailing list "dp@acn.purdue.edu" is available. This list is a group of people either using or thinking about using this software. To subscribe to this list, send an email message to majordomo@acn.purdue.eduwith the text

	index dp

To retrieve an archive, send mail to majordomo@acn.purdue.edu with the text

	get dp

for example:

	get dp 95.03

Majordomo will respond by sending you all of the messages in the selected archive as individual mail messages.

To interactively search the archives using your Web browser, use the URL

	http://www.acn.purdue.edu/maise/cgi-bin/maise/dp

Kirk Smith / ks@acn.purdue.edu Last updated: 16 August 1995