Restricted Shell

There  are  restricted editions of  the  Bourne and  Korn  shells  (rsh  and  rksh),  which  prohibit modifying directory with cd, setting the value of $PATH, using command names holding slashes, and redirecting output using > and >>.

/etc/login.defs

This file (/etc/login.defs) permits to describe some useful default values for several programs like as useradd and password expiry. That tends to vary slightly across distributions and even edition, but classically is well commented and tends to hold sane default values.

/etc/shells

The shells file holds a list of valid shells, if a user's default shell is not listed here they might not log in interactively.

/etc/securetty

This file holds a list of tty's which the root can log in from. Console tty's are commonly /dev/tty1 through /dev/tty6. Serial ports are /dev/ttyS0 and up typically. If root is to be permited to login via the network then add /dev/ttyp1   have to added and up. Generally only root should be permited to login from /dev/tty1, and it is sensible to disable the root account altogether. Earlier than doing this sudo or program has to be installed that allows root access to commands.

Note :

How to for the short term disable user logins (Solaris )

The given procedures display how to temporarily disable user logins in Solaris

Become superuser.

Create the /etc/nologin file using an editor.

 # vi /etc/nologin

Involve a message regarding system availability.

Close and save the file.

Example-Disabling User Logins

The given example shows how to notify users of system unavailability.

# vi /etc/nologin

(Add system message here)

# cat /etc/nologin

***No logins permitted***

***The system should be unavailable until 12 noon***

Note: Within regard to disabling   logins,   it   will   work and there   is   no   "nologin" file concept   in SCO in   Solaris.   Moreover, the /etc/profile can be edited with a suitable message within the last line as /bin/true and exit. That will throw all the users who are trying to login. To ensure which it does not throw the root, a condition through checking the LOGNAME for non-root has to be added.