To act as a PPP server, the LEAF router must listen for incoming connections on one or more modem (serial port) lines. This process is similar to listening for a shell login from the console, though the details differ.

To listen for an incoming connection, you use the program "mgetty" to watch a serial device. You set this up in the '/etc/inittab' file. Some versions of LEAF have inactive (commented out) lines in inittab for this purpose, but newer versions do not. So you need either to add or to activate (uncomment) a line like this one:

T0:23:respawn:/sbin/mgetty ttyS0 -D ttyS0 -s 115200

This sample line assumes the model uses the first serial port (Windows' COM1 normally corresponds to Linux's ttyS0) and a line speed of 115200 bps (sometimes called "baud", though this usage is technically inaccurate).

This line tells the init process to have mgetty listen on ttyS0 and process a connection when one arrives. Next, you need to tell mgetty *how* to process that connection You do so by editing (or creating) the files "/etc/mgetty/mgetty.config" and "/etc/mgetty/login.config'" as follows (suitably modified if you use a different port or line speed):

# The '/etc/mgetty/mgetty.config' file:
# mgetty configuration file
 port ttyS0
 init-chat "" AT&F1&C1&D2
 speed 115200
 debug 3
 data-only y

Modify the '/etc/mgetty/login.config' file:

/AutoPPP/	ppp	ttyS0 	/usr/sbin/pppd