Firewalls can't protect very well against things like viruses or malicious software (malware). There are too many ways of encoding binary files for transfer over networks, and too many different architectures and viruses to try to search for them all. In other words, a firewall cannot replace security-consciousness on the part of your users. In general, a firewall cannot protect against a data-driven attack--attacks in which something is mailed or copied to an internal host where it is then executed.

Alternate Answer:
Properly configured firewalls can limit the propagation of worms - a form of malware.  Typically, firewalls are edge or parameter devices (separates network zones) and most viruses and malware targets end points (user workstations and servers).

Multiple processes must agree that they will share the same connection, where every parameter is the same, including the security settings.  The connection string must be identical.

Security can be handled at the machine, domain, or sharepoint level.

By default, all sites are created private.If you want your site to be a public Web site, enable
anonymous access for the entire site. Then you can give out your URL to anybody in your
business card, e-mail or any other marketing material. The URL for your Web site will be:
http:// yoursitename.wss.bcentral.com
Hence, please take special care to name your site.
These Web sites are ideal for information and knowledge intensive sites and/or sites where you
need to have shared Web workspace.
Remember: Under each parent Web site, you can create up to 10 sub-sites each with unique
permissions, settings and security rights

SharePoint-based Web sites can be password-protected to restrict access to registered users, who
are invited to join via e-mail. In addition, the site administrator can restrict certain members' roles
by assigning different permission levels to view post and edit.

Microsoft Windows SharePoint Services Technical security measures provide firewall protection,
intrusion detection, and web-publishing rules. The Microsoft operation center team tests and
deploys software updates in order to maintain the highest level of security and software reliability.
Software hot-fixes and service packs are tested and deployed based on their priority and level of
risk. Security related hot-fixes are rapidly deployed into the environment to address current
threats. A comprehensive software validation activity ensures software stability through regression
testing prior to deployment.