192.168.0.10
192.168.0.11
To setup the second IP you will have to add a second Ethernet Adapter (logical not physical).
192.168.0.10 dev.foo.com
192.168.0.11 dev.bar.com
sudo ifconfig lo0 192.168.0.10 alias
sudo ifconfig lo0 192.168.0.11 alias
sudo ipfw add fwd 127.0.0.1,123 tcp from me to 192.168.0.10 dst-port 80
sudo ipfw add fwd 127.0.0.1,456 tcp from me to 192.168.0.11 dst-port 80
You are done !
Now :
http://dev.foo.com redirects to localhost:123 http://dev.bar.com redirects to localhost:456