Prevent access to local Apache on OS X with ipfw

ipfw.conf

add 1000 deny tcp from any to any dst-port 80 recv en0
add 2000 deny tcp from any to any dst-port 80 recv en1
add 3000 deny tcp from any to any dst-port 80 recv en3
# The next one works only if you have tun/tap driver installed for VPN apps. If you do not have it, comment it.
add 4000 deny tcp from any to any dst-port 80 recv tun0

ipfw.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://
     www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
    <string>ipfw</string>
  <key>Program</key>
    <string>/sbin/ipfw</string>
  <key>ProgramArguments</key>
    <array>
      <string>/sbin/ipfw</string>
      <string>/etc/ipfw.conf</string>
    </array>
  <key>RunAtLoad</key>
    <true />
</dict>
</plist>

shell command

sudo launchctl load -w /Library/LaunchDaemons/ipfw.plist