BURTON-KELLY, M.E. and J.M. ERICKSON. 2010. A new occurrence of Protichnites Owen, 1852, in the Late Cambrian Potsdam Sandstone of the St. Lawrence Lowlands. The Open Paleontology Journal 3:1-13.
Beyond creating a new user, you need to add their name to the bottom of /etc/ssh/sshd_config:
AllowUsers user1 user2 user3
# /etc/init.d/ssh restart