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25.3. A sample /etc/ppp/ip-up script

The example below provides a variety of example uses.

# Script which handles the routing issues as necessary for pppd
# Only the link to Newman requires this handling.
# When the ppp link comes up, this script is called with the following
# parameters
#       $1      the interface name used by pppd (e.g. ppp3)
#       $2      the tty device name
#       $3      the tty device speed
#       $4      the local IP address for the interface
#       $5      the remote IP address
#       $6      the parameter specified by the 'ipparam' option to pppd
case "$5" in
# Handle the routing to the Newman Campus server
                /sbin/route add -net gw
# and flush the mail queue to get their email there asap!
                /usr/sbin/sendmail -q &
# Our Internet link
# When the link comes up, start the time server and synchronise to the world
# provided it is not already running
                if [ ! -f /var/lock/subsys/xntpd ]; then
                        /etc/rc.d/init.d/xntpd.init start &
# Start the news server (if not already running)
                if [ ! -f /var/lock/subsys/news ]; then
                        /etc/rc.d/init.d/news start &
# Get the email down to my home machine as soon as the link comes up
# No routing is required as my home Ethernet is handled by IP
# masquerade and proxyarp routing.
                /usr/sbin/sendmail -q &
exit 0

As a result of bringing up the ppp link to our Newman campus and this script, we end up with the following routing table entries (this machine also is our general dial up PPP server AND handles our Internet link). I have interspersed comments in the output to help explain what each entry is) :-

[root@kepler /root]# route -n
Kernel routing table
Destination     Gateway         Genmask         Flags MSS    Window Use Iface
# the HOST route to our remote internet gateway   *      UH    1500   0      134 ppp4
# the HOST route to our Newman campus server    *      UH    1500   0       82 ppp5
# the HOST route to my home ethernet    *      UH    1500   0       74 ppp3
# two of our general dial up PPP lines     *      UH    552    0        0 ppp2     *      UH    552    0        1 ppp1
# the specific network route to the Newman campus LAN   UG    1500   0        0 ppp5
# the route to our local Ethernet (super-netting two adjacent C classes)      *        U     1500   0     1683 eth0
# the route to the loop back device       *            U     3584   0      483 lo
# the default route to the Internet
default   *               UG    1500   0     3633 ppp4