Save the file and make it executable:

chmod +x /etc/ppp/ppplogin

Now create or update the /etc/ppp/options file:

In the above replace with the IP address of your LAN’s DNS server. In our case, the machine 192.168.1.15 acts as our DNS, so we used:

ms-dns 192.168.1.15

Create another file /etc/ppp/options.ttyS0 and add the following to it:

:

For example, we used ws120.cmil.com:192.168.1.200

The hostname can be had by running the hostname command. You could also look into the /etc/HOSTNAME file. The second address is allocated to the remote system. Any unused IP address on your network should do.

Also remember to set PPPD as SUID root as it configures a network interface and manipulates kernel routing tables. All this requires special privileges. To do this, run the command:

# chmod +s /usr/sbin/pppd

Finally, let’s update the PAP authentication database. This is simple, we are going to validate users against the standard /etc/passwd, so all you need to do is edit the file /etc/ppp/pap-secrets, and add one line for every IP address you are going to allocate to a dial-in connection. In our setup, /etc/ppp/pap-secrets looks like this:

You might add more lines that are identical to the last one shown above, one for every IP address you’ll be using.