Installing and Administering PPP

40 Chapter 2
Setting Up PPP Connections
Additional Information
Additional Information
This section discusses some additional information that may be useful
when configuring PPP connections.
Non-Generic Login Scripts
In most cases, all inbound PPP logins can use the same generic Login
script. But if you want a host to start pppd with a special option like
'require authentication', make that login account use a specific login
shell that is tailored to that host. Call it /etc/ppp/Login-host, for
example, and change the pppd line to reflect whatever options you wish
to have. For example:
exec pppd `hostname`:robin idle 130 requireauth
See the pppd(1) man page for more information on options.
Creating a Simple Filter File
NOTE The Filter file is not necessary for pppd operation. It is only discussed
here as an example on how you might use the Filter file.
The PPP Filter file specifies the ways in which static packet filtering
handles outbound and inbound TCP/IP packets. Though the filtering can
be very complex if desired, a simple filter will suffice for demonstration
purposes between robin and lark.
An example other than the one shown below is in /etc/ppp/Filter.ex
and a lengthy explanation of static packet filtering is included in
Chapter 5.
Here is a Filter file that could be used for testing the robin-lark link:
default bringup !ntp !3/icmp !who
keepup !send !ntp !3/icmp !who
pass !route
log !nntp tcp/syn/recv
This filter defines the following:
(!ntp) (!3/icmp) (!who)