Apple LaserWriter 12/640 PS - Manual (Page 156)

2 When requested to do so, type the IP address of the subnet mask in the following format,
then press Enter:
XXX.XXX.XXX.XXX, where each XXX is a number between 0 and 255.
To indicate that you don’t want to specify a subnet mask, type 0.0.0.0 and
press Enter.
Setting the default gateway address
If your local network is attached to other networks, you can specify the IP
address of your local gateway. Whenever the printer needs to send messages
to another network, it will use this gateway.
1 From the main menu of the TCP/IP Printer Configuration Utility menu, press 6 and Enter.
2 When requested to do so, type the IP address of the gateway in the following format,
then press Enter:
XXX.XXX.XXX.XXX, where each XXX is a number between 0 and 255.
Note: If you enter an invalid address for the gateway or if the gateway goes
down, the printer may not be able to communicate with remote networks.
Enabling or disabling connection timeout checking
The timeout feature automatically severs TCP/IP connections that are idle for
more than 5 minutes. Under most circumstances, you should leave this
function enabled.
1 From the main menu of the TCP/IP Printer Configuration Utility menu, press 7 and Enter.
2 Follow the instructions on your screen.
Changing the password for this utility
1 From the main menu of the TCP/IP Printer Configuration Utility menu, press 8 and Enter.
2 When requested to do so, type a 5–10 character password.
The characters you type will not appear on the screen.
131 Setting Up the Printer for UNIX Users