disable user login

[peterchu]

our users use telnet to access our linux system , how to temporaily disable user login and only accept system administrator to telnet to the system ? thx

[Karthik S S · Accepted solution]

In /etc/profile add the following lines,

user=`whoami`
if [ $user != root ]
then
exit
fi

-Karthik S S

[Mark Grant]

Actually, there is a simpler way.

> /etc/nologin

the Linux "login" command will only allow root to login if /etc/nologin exists.

[Karthik S S]

Oh .. I didn't know about that...!!

Does it apply to hp-ux as well??

-Karthik S S

[Mark Grant]

Karthik, Hi!

I thought it did but it doesn't look like it. You could of course, modify your code above to include a check for /etc/nologin and then it would work on HPUX too :)

[Karthik S S]

Hi Mark :-),

This is for you ;-)

user=`whoami`
grep $user /etc/nologin
if [ $? -eq 0 ]
then
exit
fi

/etc/nologin will contain users to be ignored.

-Karthik S S

[Fred Ruffet]

You could also modify user to use /bin/false as shell :
usermod -s /bin/false

[Stuart Browne]

What Karthik was referring too was a default on a RH system.. From '/etc/pam.d/login':

auth required /lib/security/pam_nologin.so

This rule states that if the /etc/nologin file exists, it will not allow logins at that time.

From '/usr/share/doc/pam-0.75/txts/README.pam_nologin':

This module always lets root in; it lets other users in only if the file /etc/nologin doesn't exist. In any case, if /etc/nologin exists, it's contents are displayed to the user.