From Doug Werth:

I will assume you are going to be setting these up for port mapping on your firewall and that you plan to have multiple printers on the outside of the firewall. I would configure it this way in NPCONFIG:

# Firewall internal address is 192.168.1.1

#

900 (network_address = 192.168.1.1

tcp_port_number = 7900

...any other npconfig statements)

901 (network_address = 192.168.1.1

tcp_port_number = 7901

...any other npconfig statements)

902 (network_address = 192.168.1.1

tcp_port_number = 7902

...any other npconfig statements)

On the firewall, you would set up port mapping to the real IP address of the printer and the true port. For example,

7900 = 10.1.1.20:9100

7901 = 10.1.1.21:9100

7902 = 10.1.1.35:9100