Configure pf Firewall

The philosophy we will use for the fire wall is that we split in 2 or 4 steps depending on if the traffic initiated outside WAN or RED side or the inside LAN or GREEN.
First of all we use a private network range on the LAN side. So we will need to use NAT to be able to communicate from the LAN to the WAN. Traffic initiated on the LAN will be send to the WAN destination using NAT. NAT will pickup the return traffic and translate it the the correct LAN host. The fact that we use a private network range, also mean we have only one public available IP address to which all traffic initiated on the WAN wil be send. We therefore need to redirect the external traffic to the right host.
Furthermore we use queues to prioritise traffic, so our web side will be responsive and video will not be hampered by a large file transfer. Queues work on the WAN interface for the LAN → WAN traffic.
The above gives use a few challenges. If for instance we use the redirect rule with pass like so:

rdr pass on $ext_if proto tcp to $ext_if port $web_ports -> $web_server

The return traffic will then go through the default queue. and not through for instance the web queue. We therefore will have a rdr and a pass rule like this.

rdr on $ext_if proto tcp to $ext_if port $web_ports -> $web_server 
pass in on $ext_if proto tcp from any to $web_server port $web_ports queue (q_web, q_pri)

The 1st rule will redirect the traffic to the right host.
The 2nd rule will pass the traffic through the WAN NIC into the firewall

The traffic is now in the firewall so we need to let it exit on the LAN NIC like this

pass out on $int_if proto tcp to $web_server port $web_ports

We also split the config in tcp and udp traffic for efficiency reasons see: NOTE link needed here to article or book.

• Setup pf.conf file