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Security Warrior by Anton Chuvakin, Cyrus Peikari

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Medium-Sized Networks

Let us now consider a small- to medium-sized business, which likely has no dedicated security staff. Although similar to the home system case, the medium-sized network has some important differences, outlined below. As discussed in Chapter 18, a company is regulated by more administrative requirements and legal responsibilities than the home office of a private citizen. Thus, the level of security and accountability is higher. Most organizations connected to the Internet have at least one firewall and some sort of DMZ set up for public servers (web, email, FTP, remote access). Many deploy intrusion detection systems and virtual private networks (VPNs). Signals coming from all these technologies need to be interpreted and dealt with The technologies deployed during the preparation stage can greatly help future identification and containment.

The security response for such an organization focuses on severe threats. It is well known that many low-severity threats (such as someone performing port scans) might be precursors for more serious attacks (such as attempted break-ins). Unfortunately, a small company rarely has the personnel to investigate them. Ideally, security reports should include more serious attacks that actually have a chance of succeeding (unlike, say, exploits for services that are not installed). A central syslog server (for Unix environments) is of great value: using freeware tools such as logcheck (http://www.psionic.com), swatch (http://www.oit.ucsb.edu/~eta/swatch/ ...

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