It is beyond the scope of this document to describe setting up a modem, so it will be asumed that your modem is functioning, which can be verified with a terminal program such as minicom.
pppd searches /etc/ppp for dial scripts and the file "options."
Here's a sample /etc/ppp/options file:
/dev/modem 57600 crtscts modem noipdefault defaultroute idle-disconnect 300
Meaning:
/dev/modem
/dev/cuax, the serial port to which the modem is connected.
57600
spd_vhi-parameter in /etc/rc.d/rc.serial).
crtscts
noipdefault
defaultroute
ppp0) when the link is up.
idle-disconnect
Next, make a script called "default", which normally means your ISP. If you want to make other scripts for routes to specific hosts, create additional scripts and name them with the remote IP address. I suppose you would do this for high-cost/speed connections to certain hosts, like an ISDN line to another office, where you know the IP address you are going to reach.
/etc/ppp/default 'ABORT' 'BUSY' 'ABORT' 'ERROR' 'ABORT' 'NO CARRIER' 'ABORT' 'NO DIALTONE' 'ABORT' 'Invalid Login' 'ABORT' 'Login incorrect' '' 'AT&F1S11=55' 'OK' 'ATDT5552000' 'CONNECT' '' 'ogin:' 'USER' 'word:' 'PASSWD'
Change the first AT string to include any modem initialization string you require. I use the S11=55 to speed up the dial tones. Also change the phone number from 5552000 to your ISP's modem access number. Change USER and PASSWD to be your actual userid and password at your ISP. Each expect/reply pair following the CONNECT line should be the prompt and response required for you to log in to the ppp server and start a session. For more information, see the ppp HOWTO.
Note to RedHat users: The above script is exactly the script generated by the GUI configuration tool off of the control-panel. You can make
/etc/ppp/defaulta link to the generated file/etc/sysconfig/network-scripts/chat-ppp0. Do this with the commandln /etc/sysconfig/network-scripts/chat-ppp0 /etc/ppp/defaultNow whenever you use the control-panel to edit your ppp script, it will still work for the on demand dialing.
Make another short script to make the ppp call:
/etc/ppp/ppp #!/bin/sh /usr/sbin/pppd connect '/usr/sbin/chat -v -f /etc/ppp/default'
You should be able to make a connection by running /etc/ppp/ppp. After the connection is made, check with ifconfig to make sure there is a ppp0 interface. Check for the default route with 'netstat -r'.
Be sure to put your nameserver in /etc/resolv.conf:
search so-and-so.domain nameserver x.x.x.x
kerneld can be used to load modules, such as ppp, on demand. As described in the kerneld-HOWTO, it can also run a script if a particular network route is missing. kerneld will try to run '/sbin/request-route'. The following is the one I use.
/sbin/request-route:
#!/bin/sh
LOCK=/var/run/request-route.pid
PATH=/usr/sbin:$PATH # for ppp-2.2*
export PATH
# Note: you are _not_ forced to use ppp!
# You can do whatever you want in order to satisfy the kernel route request.
# It might be a good idea to set up the route as the default route, in case
# you are using e.g. slip or plip or any other net driver...
#
# This script will be called from kerneld with the requested route as $1
# Create a chat script for your nameserver (as defined in /etc/resolv.conf)
#
#This script will be called from kerneld with the requested route as $1
chatfile=/etc/ppp/$1
# If no chatscript exists use a default value (symlink to preferred script):
[ ! -f $chatfile ] && chatfile=/etc/ppp/default
# Check if we're already running:
if [ ! -f $LOCK ]; then
pppd connect "chat -f $chatfile" &
# Timer to be killed by ip-up, tunable! Check kerneld delay as well
sleep 60 &
sleepid=$!
echo $sleepid > $LOCK
wait $sleepid
rm -f $LOCK
exit 0
fi
exit 1
kerneld will run this script using the missing route as an arugument:
/sbin/request-route x.x.x.x
After the link has been activated, pppd runs the script /etc/ppp/ip-up. Add commands you want to execute each time the link is brought up to /etc/ppp/ip-up.local. Here is mine:
/etc/ppp/ip-up.local: #!/bin/bash # # $1 interface name # $2 tty device # $3 speed # $4 local ip address # $5 remote ip address # wait 40 seconds and set the clock # change x.x.x.x to an accurate time server. run rdate host to test it. (sleep 40; /usr/bin/rdate -s x.x.x.x)&
The "idle-disconnect" option automatically disconnects the link after it is idle for the time specified. Use "ppp-off" to disconnect immediately:
/usr/sbin/ppp-off
#!/bin/sh
LOCK=/var/run/request-route.pid
DEVICE=ppp0
rm -f $LOCK
#
# If the ppp0 pid file is present then the program is running. Stop it.
#
if [ -r /var/run/$DEVICE.pid ]; then
kill -INT 'cat /var/run/$DEVICE.pid'
#
# If unsuccessful, ensure that the pid file is removed.
#
if [ ! "$?" = "0" ] ; then
echo "removing stale $DEVICE pid file."
rm -f /var/run/$DEVICE.pid
exit 1
fi
#
# Success. Terminate with proper status.
#
echo "$DEVICE link terminated"
exit 0
fi
#
# The link is not active
#
echo "$DEVICE link is not active"
exit 1
With this configured, any outgoing packet will cause the ppp link to come up. I have set up a crontab entry to cause the connection to come up every 15 minutes during the day by sending one ping to my nameserver. I do this so I can access my system within ten minutes. The connection is timed out after five minutes if there is no further activity. Add a crontab entry as follows:
crontab -e # insert this line */15 6-23 * * 1-5 /bin/ping -c 1 x.x.x.x >& /dev/null
The meaning of this entry is: every 15 minutes from 0600 to 2359 Monday-Friday ping host x.x.x.x with one packet, sending stdout and stderr to /dev/null because I don't want an mail message every 15 minutes. See the crontab man page for more info.
Something else I would like to set up is a program to listen for the phone to ring once, wait a minute, then dial out. That way I could call my computer, and a couple minutes later be able to connect with it.