How do I connect to an SMB share requiring a user name and password?

In top menu of the file browser click Go>Location and enter smb://user@host/sharename. You will then be prompted to enter a password.

If you have a Guest account without a password:

smb://Guest:@server_name

If you have a user account with a password:

smb://user_name:password@server_name

If you have a user account but only want to be prompted for the password:

smb://user_name:*@server_name