iproute - Professional tools to control the networking in Linux kernels
======================================================== Routing
The router has three ethernet segments and one PPP link

root# route add -net 192.168.1.0 netmask 255.255.255.0 eth0
root# route add -net 192.168.2.0 netmask 255.255.255.0 eth1
root# route add -net 192.168.3.0 netmask 255.255.255.0 eth2
root# route add default ppp0

serial link protocols such as PPP and slip only ever have two hosts on their
network, one at each end. To specify the host at the other end of the link as
the gateway is pointless and redundant as there is no other choice, so you do
not need to specify a gateway for these types of network connections. Other
network types such as ethernet, arcnet or token ring do require the gateway to
be specified as these networks support large numbers of hosts on them. 
========================================================
route del -net 0.0.0.0 gw 198.144.195.41 eth1

fetchipac	- ip accounting kernel data and database handler
ipac-ng
ipacsum