In the /etc/passwd file there are several default system users that have valid shells:


Code:
user: daemon     shell: /bin/sh
user: bin        shell: /bin/sh
user: sys        shell: /bin/sh
user: sync       shell: /bin/sync
user: games      shell: /bin/sh
user: man        shell: /bin/sh
user: lp         shell: /bin/sh
user: mail       shell: /bin/sh
user: news       shell: /bin/sh
user: uucp       shell: /bin/sh
user: proxy      shell: /bin/sh
user: www-data   shell: /bin/sh
user: backup     shell: /bin/sh
user: list       shell: /bin/sh
user: irc        shell: /bin/sh
user: gnats      shell: /bin/sh
user: nobody     shell: /bin/sh
user: libuuid    shell: /bin/sh
user: statd      shell: /bin/false
user: sshd       shell: /usr/sbin/nologin
I would like to set many of these to /bin/false or nologin, but Im not sure if that's safe to do.