Linux Network Administrator's Guide, Second Edition

Configuring IP Accounting

Because IP accounting is closely related to IP firewall, the same tool was designated to configure it, so ipfwadm, ipchains or iptables are used to configure IP accounting. The command syntax is very similar to that of the firewall rules, so we won’t focus on it, but we will discuss what you can discover about the nature of your network traffic using this feature.

The general syntax for IP accounting with ipfwadm is:

# ipfwadm -A [
               direction
               ] [
               command
               ] [
               parameters
               ]

The direction argument is new. This is simply coded as in, out, or both. These directions are from the perspective of the linux machine itself, so in means data coming into the machine from a network connection and out means data that is being transmitted by this host on a network connection. The both direction is the sum of both the incoming and outgoing directions.

The general command syntax for ipchains and iptables is:

# ipchains -A 
               chain 
               rule-specification
# iptables -A 
               chain 
               rule-specification

The ipchains and iptables commands allow you to specify direction in a manner more consistent with the firewall rules. IP Firewall Chains doesn’t allow you to configure a rule that aggregates both directions, but it does allow you to configure rules in the forward chain that the older implementation did not. We’ll see the difference that makes in some examples a little later.

The commands are much the same as firewall rules, except that the policy rules do not apply here. We can add, insert, ...