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49.1 Local Security and Network
There are several ways of accessing data:
• personal communication with people who have the desired information or access
to the data on a computer
• directly from the console of a computer (physical access)
• over a serial line
• using a network link
In all these cases, a user should be authenticated before accessing the resources or data
in question. A Web server might be less restrictive in this respect, but you still would
not want it to disclose all your personal data to any surfer.
In the list above, the first case is the one where the highest amount of human interaction
is involved, such as when you are contacting a bank employee and are required to prove
that you are the person owning that bank account. Then you are asked to provide a
signature, a PIN, or a password to prove that you are the person you claim to be. In
some cases, it might be possible to elicit some intelligence from an informed person
just by mentioning known bits and pieces to win the confidence of that person by using
clever rhetoric. The victim could be led to reveal gradually more information, maybe
without even becoming aware of it. Among hackers, this is called social engineering.
You can only guard against this by educating people and by dealing with language and
information in a conscious way. Before breaking into computer systems, attackers often
try to target receptionists, service people working with the company, or even family
members. In many cases, such an attack based on social engineering is only discovered
at a much later time.
A person wanting to obtain unauthorized access to your data could also use the tradi-
tional way and try to get at your hardware directly. Therefore, the machine should be
protected against any tampering so that no one can remove, replace, or cripple its
components. This also applies to backups and even any network cable or the power
cord. Also secure the boot procedure, because there are some well-known key combi-
nations that might provoke unusual behavior. Protect yourself against this by setting
passwords for the BIOS and the boot loader.
880
Installation and Administration
Security
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Troubleshooting
