Trustin's /etc/pf.conf for Mac OS X

pf.conf

# 1. Put this file to /etc/pf.conf
# 2. Install init boot scripts using IceFloor then - http://www.hanynet.com/icefloor/
#    I tried to use IceFloor to configure everything but it didn't work very well.
# 3. Once done, you can confirm the rules were loaded with 'sudo pfctl -sr'
# 4. At System Preferences -> Security -> Firewall -> Firewall Options,
#    check 'Block all incoming connections' to prevent annoying per-app dialogs.

set skip on lo0
set block-policy drop

block in all
pass out all

# Localhost access

# Ping
pass in proto icmp all

# SSH
pass in proto tcp from any to port 22

# DNS
pass in proto tcp from any to port 53
pass in proto udp from any to port 53

# DHCP
pass in proto tcp from any to port 67:68
pass in proto udp from any to port 67:68

# NTP
pass in proto tcp from any to port 123
pass in proto udp from any to port 123

# mDNS
pass in proto tcp from any to port 5353:5354
pass in proto udp from any to port 5353:5354

# BitTorrent (Transmission)
pass in proto tcp from any to port 51413
pass in proto udp from any to port 51413

# Skype
pass in proto tcp from any to port 32814
pass in proto udp from any to port 32814

DHCP and NTP do not use TCP protocol so I guess there are some odd rules here...