HP-UX

Dear Forum,

I had this case before, all of sudden all users including root can't login. What done is by connecting to console port and resetting root password, "pwunconv" command, reboot server.

My question is, how this can happen???

thanks

Well you must be more clear:
What system are you talking about? a server?
I a server, usually it has no graphic card...
Your issue seems to come from a manipulation where the system is turned to trusted mode (otherwise pwunconv doesnt make sence).
So
1) Is your system a trusted server?

2) If not, what was the last commands root user entered

It is quite easy to convert or unconvert trusted with SAM by accident. If you are intentionally trusted beware that the reverse convert loses all the user account passwords. As "vbe" states you need to know whether your system is normally trusted or not.
SAM has a log and a log viewer.

Code:

/usr/sam/bin/samlog_viewer

Also check that you don't have a file called /etc/nologin (with NOLOGIN=1 in /etc/default/security). It will give these symptoms.

Is inetd running?
Anything unusual in syslog?

If you have tried to convert your system to trusted system, or vice-versa, all your users' status have been changed to LOCKED. You need to unlock the users one by one.

Code:

cat /etc/passwd | while read uline; do
UNAME=$(echo $uline | cut -d: -f1)
/usr/lbin/modprpw -l -m alock=NO $UNAME  #unlocks the account
/usr/lbin/modprpw -k $UNAME #resets incorrect login count
done

hope this helps