DA-710 Series Linux
Managing Communications
3-18
PPP (Point to Point Protocol)
PPP (Point to Point Protocol) is used to run IP (Internet Protocol) and other network protocols over a serial link.
PPP can be used for direct serial connections (using a null-modem cable) over a Telnet link, and links
established using a modem over a telephone line.
Modem/PPP access is almost identical to connecting directly to a network through the DA-710-LX’s Ethernet
port. Since PPP is a peer-to-peer system, the DA-710-LX can also use PPP to link two networks (or a local
network to the Internet) to create a Wide Area Network (WAN).
ATTENTION
Click on the following links for more information about PPP.
http://tldp.org/HOWTO/PPP-HOWTO/index.html
http://axion.physics.ubc.ca/ppp-linux.html
Connecting to a PPP Server over a Simple Dial-up Connection
The following command is used to connect to a PPP server by modem. Use this command for old ppp servers
that prompt for a login name (replace “username” with the correct name) and password (replace “password”
with the correct password). Note that “debug crtscts” and “defaultroute 192.1.1.17” are optional.
#pppd connect ‘chat -v ““ ATDT5551212 CONNECT ““’ ogin: username word: password’
/dev/ttyM0 115200 debug crtscts modem defaultroute 192.1.1.17
If the PPP server does not prompt for the username and password, the command should be entered as follows.
Replace “username” with the correct username and replace “password” with the correct password.
#pppd connect ‘chat -v ““ ATDT5551212 CONNECT ““’ user username password password
/dev/ttyM0 115200 crtscts modem
The pppd options are described below:
connect ‘chat etc...’
This option gives the command to contact the PPP server. The
chat
program is used
to dial a remote computer. The entire command is enclosed in single quotes because
pppd expects a one-word argument for the
connect
option. The options for
chat
are given below:
-v
verbose mode; log what we do to syslog
“ “
Double quotes—don’t wait for a prompt, but instead do ... (note that you must
include a space after the second quotation mark)
ATDT5551212
Dial the modem, and then ...
CONNECT
Wait for an answer.
“ “
Send a return (null text followed by the usual return)
ogin: username word: password
Log in with username and password.
Refer to the chat man page, chat.8, for more information about the
chat
utility.
/dev/
Specify the callout serial port.
115200
The baud rate.
debug
Log status in syslog.
crtscts
Use hardware flow control between computer and modem
(at 115200 this is a must).
modem
Indicates that this is a modem device; pppd will hang up the phone before and after
making the call.
defaultroute
Once the PPP link is established, make it the default route; if you have a PPP link to
the Internet, this is probably what you want.
