Canon LBP6780x Manual page 445

When not using proxy functions
Clear the [Use Proxy] check box.
(3) Set proxy authentication functions.
When using proxy authentication functions
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].
Enter the user name used for proxy authentication. Up to 24 alphanumeric
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 alphanumeric characters can be entered.
To confirm the password, enter the entered [Password] again.