Canon LBP7660Cdn Manual page 460

Select the [Use Proxy Authentication] check box, and set the following items.
[User Name]
[Set/Change
Password]
[Password]
[Confirm]
When not using proxy authentication functions
Clear the [Use Proxy Authentication] check box.
(4) Click [OK].
Proceed to Step
Multicast Discovery Settings
Set whether the printer will respond to device searches over the network using Multicast Discovery.
(1) Click [Edit...] in [Multicast Discovery Settings].
Enter the user name used for proxy authentication. Up to 24 characters can be
entered.
Select the check box to use a password for proxy authentication. When you are not
using a password for proxy authentication, clear the check box.
When [Set/Change Password] is selected, enter the password used for proxy
authentication. Up to 24 characters can be entered.
To confirm the password, enter the entered [Password] again.
6 if you do not specify the settings for the other options.