lan_net = "10.7.2.0/24"
int_if = "fxp0"
ext_if1 = "rl0"
ext_if2 = "em0"
ext_if1 = "rl1"
ext_if2 = "rl2"
ext_gw1 = "10.7.3.1"
ext_gw2 = "10.7.4.1"
ext_gw3 = "10.7.5.1"
ext_gw4 = "10.7.6.1"
# nat outgoing connections on each internet interface
nat on $ext_if1 from $lan_net to any -> ($ext_if1)
nat on $ext_if2 from $lan_net to any -> ($ext_if2)
nat on $ext_if3 from $lan_net to any -> ($ext_if3)
nat on $ext_if4 from $lan_net to any -> ($ext_if4)
# default deny
block in from any to any
block out from any to any
# pass all outgoing packets on internal interface
pass out on $int_if from any to $lan_net
# pass in quick any packets destined for the gateway itself
pass in quick on $int_if from $lan_net to $int_if
# load balance outgoing tcp traffic from internal network.
pass in on $int_if route-to { ($ext_if1 $ext_gw1), ($ext_if2 $ext_gw2), ($ext_if3 $ext_gw3), ($ext_if4 $ext_gw4i) } round-robin proto tcp from $lan_net to any flags S/SA modulate state
# load balance outgoing udp and icmp traffic from internal network
pass in on $int_if route-to { ($ext_if1 $ext_gw1), ($ext_if2 $ext_gw2), ($ext_if3 $ext_gw3), ($ext_if4 $ext_gw4i) } round-robin proto { udp, icmp } from $lan_net to any keep state
# general "pass out" rules for external interfaces
pass out on $ext_if1 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if1 proto { udp, icmp } from any to any keep state
pass out on $ext_if2 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if2 proto { udp, icmp } from any to any keep state
pass out on $ext_if3 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if3 proto { udp, icmp } from any to any keep state
pass out on $ext_if4 proto tcp from any to any flags S/SA modulate state
pass out on $ext_if5 proto { udp, icmp } from any to any keep state
# route packets from any IPs on $ext_if1 to $ext_gw1 and the same for
# $ext_if2 and $ext_gw2
pass out on $ext_if1 route-to ($ext_if2 $ext_gw2) from $ext_if2 to any
pass out on $ext_if2 route-to ($ext_if1 $ext_gw1) from $ext_if1 to any