ppp.Devices - PPP physical device description file format


The file /usr/lib/mstppp/Devices on SCO systems associates dialer types with physical devices and speeds. Pppd examines it when placing a call to a neighboring machine. If no suitable speed is found, or if all dev ices associated with that speed are busy, pppd will try again later.


Contains either the string `Direct, the name of the modem dialing chat script in Dialers to use with this device, or the name of an external dialer program.
The name of the device in the /dev directory ( tty1a, tty1A , etc.). Device names for SnapLink connections are followed by a slash and the port number in use ( rfd0, rfd1 , etc.).
The baud rate of the synchronous connection, or a string to be matched against the speed field of entries in Systems when the Systems device field is set to ACU (Any Call Unit).

There is also a fourth field for describing options:

optional parameters
Any special handling for this device. Currently supported values are shown in the table below.
Specifies that the line be conditioned for out-of-band EIA RS-232-D `hardware (RTS/CTS) flow control. The default is to use no flow control. For an outbound connection, this may be specified either in Devices or on the pppd command line.
A synonym for rtscts
Specifies that the line be conditioned for in-band (`software) flow control, using the characters DC3 (^S, XOFF, ASCII 0x13) to stop the flow and DC1 (^Q, XON, ASCII 0x11) to resume. The default is to use no flow control. For an outbound connection, this may be specified either in Devices or on the pppd command line.
The SnapLink will provide the synchronous clock signal. By default, it expects the modem, CSU/DSU or modem eliminator to provide the clock signal. Internal-clocking cannot be used with RS-232 cables on the SnapLink.
A SnapLink will calculate 32-bit FCS values for transmitted frames, and check received frames with 32-bit FCS calculations. This is not negotiable at connection establishment time. 32-bit FCS is only available when running synchronous PPP on the SnapLink.
min-flags=min flags
The number of additional HDLC flag characters a SnapLink should insert between data frames. The default and minimum is 2; the maximum is 16.
Ignore the state of the CD (Carrier Detect, also called DCD, Data Carrier Detect) signal. This is useful for systems that don't support CD but want to run PPP over a dedicated line.


The external dialer program is run with the following arguments:

device name
The contents of the Device field from the Devices entry
The contents of the Speed field of the Systems and Devices entries.
telephone number
The contents of the Phone Number field of the Systems entry.

This program also allows for optional parameters:

optional parameters
Copied from the Optional Parameters section of the Devices entry. If the external dialer program exits with status 0, then the dial attempt is considered to have succeeded. Any other exit status indicates a failure.


# Devices - PPP devices file

#Dialer device speed Optional parameters
T2500-PEP cua 19200-PEP rtscts
T1600 cub 38400 rtscts
Direct rsd0a/0 1536000 internal-clocking
Oddball rsd0a/1 64000 cua 9600 5551212

In the last line of this example, the 64Kb synchronous modem on the SnapLinks port 1 has an asynchronous dialer interface attached to the workstations port `a' The Systems line would look like

host Oddball rsd0a/1 64000 0

There must be a program (or an executable shell script) called /usr/lib/mstppp/Oddball that dials the modem when invoked as

Oddball rsd0a/1 64000 0 cua 9600 5551212

A warning message will be printed for each unrecognized optional parameter if the debug level is 2 or more.


The external dialer is invoked as root , so you should take appropriate security precautions with its content and file protection.


tun(MST_PPP), ppp.Auth (MST_PPP), ppp.Dialers (MST_PPP), ppp.Filter (MST_PPP), ppp.Keys (MST_PPP), ppp.Systems (MST_PPP), pppd (MST_PPP), RFC 1661 , RFC 1332, RFC 1144 , RFC 1055 .


Copyright 1991, 1992, 1993, 1994, 1995, 1996 Morning Star Technologies Inc.; all rights reserved.