We have 5 static IP addresses from our ISP:

XXX.XXX.XXX.180
XXX.XXX.XXX.181
XXX.XXX.XXX.182
XXX.XXX.XXX.183
XXX.XXX.XXX.184

On our firewall box, the NIC that is connected to our cable modem, appears to have all 5 IP addresses set on it. A previous IT guy set this thing up, and I'm not sure exactly what he did. Are these virtual interfaces on this NIC or what? Here is my ip addr output for that NIC:

rwd0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether XX:XX:XX:XX:XX:XX brd ff:ff:ff:ff:ff:ff
    inet XXX.XXX.XXX.180/24 brd XXX.XXX.XXX.186 scope global rwd0
    inet XXX.XXX.XXX.181/29 brd XXX.XXX.XXX.186 scope global rwd0:FWB9
    inet XXX.XXX.XXX.182/29 brd XXX.XXX.XXX.186 scope global secondary rwd0:FWB10
    inet XXX.XXX.XXX.183/29 brd XXX.XXX.XXX.186 scope global secondary rwd0:FWB11
    inet XXX.XXX.XXX.184/29 brd XXX.XXX.XXX.186 scope global secondary rwd0:FWB12
    inet6 fe80::250:8bff:fe61:5734/64 scope link 
       valid_lft forever preferred_lft forever

I'm a bit new to firewalls and networking so I'm just trying to figure out what he had going on here. I know he used Firewall Builder to configure the iptables rules, maybe that has something to do with the "FWB" I see in those names?

So my questions are:

1. What is going on here? Virtual Interfaces? Or something else?

2. If we want to put in a second firewall in parallel with this firewall but we only want it to handle traffic to XXX.XXX.XXX.182, how do we get rid of the static XXX.XXX.XXX.182 address on this existing firewall box?