Who is doing something on the system

apt-get install acct
yum install psacct

The ac command displays statistics about how long users have been logged on.
The lastcomm command displays information about previous executed commands.
The accton command turns process accounting on or off.
The sa command summarizes information about previously executed commmands.

ac -d
ac -p
lastcomm [user]
lastcomm [command]
sa
sa -u

Brouter

What is it that brouter? It is a new network device that employs bridge and router capabilities in one device allowing to process routable Layer3 – network layer e.g. IP, IPSec protocols and non-routable ones of Layer2 – data link layer. So it acts like a bridge for the intranet and as a router for the extranet.