Basic IPF Config Example
Kyle Amon,  Page 6 
/etc/ipf.rules

  #================================================================.
  # Internal Interface [rl1]                                       |
  #================================================================+

  #----------------------------------------------------------------.
  # Allow TCP/UDP/ICMP connections from internal to anywhere       |
  #----------------------------------------------------------------+

  pass in quick on rl1 proto tcp from any to any keep state
  pass in quick on rl1 proto udp from any to any keep state
  pass in quick on rl1 proto icmp from any to any keep state

  #----------------------------------------------------------------.
  # Allow TCP/UDP/ICMP connections from ifsec to anywhere          |
  #----------------------------------------------------------------+

  pass out quick on rl1 proto tcp from ifsec to any keep state
  pass out quick on rl1 proto udp from ifsec to any keep state
  pass out quick on rl1 proto icmp from ifsec to any keep state

  #----------------------------------------------------------------.
  # Block and log everything else                                  |
  #----------------------------------------------------------------+

  block in log on rl1
  block out log on rl1

  #----------------------------------------------------------------.
  # Logging override for things not to log                         |
  #----------------------------------------------------------------+

  block in quick on rl0 from any to any port = netbios-ns
  block in quick on rl0 from any to any port = netbios-dgm
  block in quick on rl0 from any to any port = netbios-ssn