Phishing,SMishing,andVishing·Chapter6 143 enforcement--if the site is reported for analysis--take down becomes tedious, if not impossible. This can be accomplished by various approaches discussed next. pf Firewall Rules Firewall rules are the simplest way to ban outside traffic to a server. In OpenBSD, pf firewall (packet filter firewall) is used to filter ingoing and outgoing traffic. Simply by adding the following rules to the pf.conf file, all outside traffic is blocked and only internal clients may have access to the Web server. block in all pass in quick on \$interface proto tcp from 192.168.1.1/24 to (\$interface) port 80 flags S/SA keep state Now when an outsider, say, a client with an external IP address, tries to access the phishing site, the following message is displayed: "The page cannot be displayed." Note that this message does not raise suspicions about the nature of the hosted site. Web Server vhost File Applying rules to the vhost file in a Web server is another approach to restrict traffic to only local clients. Using the allow and deny rules in the vhost file, as shown in Figure 6.3,