Keep Out: Spam and Viruses

Good security requires defense in depth—that is, layers of protection at every level of your network. Although small-to-midsized businesses (SMBs) might not have much in common with enterprises when it comes to budget, staff, resources, or requirements, their overall security needs are pretty similar to those of large businesses. I want to talk about two specific defensive security measures—antispam and antivirus protection—and how SMBs can deploy them in multiple layers of protection. I start with some concepts that are common to both measures, then branch out and provide specific strategies to maximize the amount of protection per dollar that you get for your network resources.

Distinguishing Good and Bad Content
Antivirus and antispam software share a common underlying function: they test messages, files, or other objects to determine whether they're "good" or "bad." I put those words in quotes because items that are bad according to one set of security rules might be good under another set. For example, at my company we develop software, so our staff members often mail scripts to one another. The same VBScript attachment that's good when sent between two internal users might be flagged as bad if it were received from an external sender. . . .