Enhancing Network Security with tcp_wrapper
Christopher Bush
More than just the Internet concerns the security-minded systems
administrator. The same technology that made the Internet what it
is - TCP/IP - has now been widely deployed on private LANs, as more
companies have realized the benefits of open systems solutions, and
software giants have embraced those solutions and technologies in
their product offerings. Now, the same vulnerabilities exist on
private internal networks, even if they aren't connected to the
Internet. It is widely recognized that most computer security
breaches result from attacks within an organization. Even if you
are connected to the Internet, and protected by a seemingly
impenetrable firewall, you still must protect yourself from attack
over the network.
So what does a savvy systems administrator do? You can cross
your fingers and hope. You can rely on your network administrator
to provide strong network security. Both are bad ideas. You should
have an overall enterprise security architecture, which consists of
many pieces. Developing an overall security strategy is far beyond
the scope of this article. I have, however, provided a list of
resources that you may wish to consult as you develop a strategy
(see sidebar "UNIX Network Security Resources"). In this article, I
will present a detailed description of one of the tactical tools
that should be included in any plan to provide solid network
security on your UNIX systems. That tool is Wietse Venema's
tcp_wrapper (sometimes called log_tcp or tcpd).
This article covers the basics of installing and using the
software, and more information is contained in an accompanying
article on the Sys Admin Web site at:
www.s
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