Archive for the ‘Fedora’ Category.

Howto generate a random password i an jiffy!

The following one-liner will generate a random eight character string consisting of numbers as well as upper- and  lowercase letters.

echo `< /dev/urandom tr -dc A-Za-z0-9 | head -c8`


tr -dc '0-9a-zA-Z' </dev/urandom |head -c8; echo

If you need a shorter or longer password you can ajust the “-c8”-value.

And yes, I know…… a password should contain special characters as well. Please feel free to add a few periods and asterisks :-)

I found this on the net somewhere. I don’t remember where – sorry.

Add a vmdk to virtual RHEL5 server

To add a vmdk to a virtaul RHEL5 server, you first of all need to create the vmdk (d’oh!) – I won’t go into that here. Next, on the RHEL5 server do as root:

echo "- - -" > /sys/class/scsi_host/host0/scan (the spaces between the dashed are important)

This will cause the scsi bus to be rescanned and the new disk should be found. For the devicename check “dmesg”. Now you can partition the disk, add it to LVM or whatever.

Expire password in Linux

If you need to force a user to change password at next login, simply use:

# chage -d 0 <userid>

Keep track of failed login attempts

To enable faillog to actually start logging failed login attempts you need to set up PAM to use the module “”. To configure PAM open the file /etc/pam.d/system-auth in your favourite editor and add the following lines to the file:

auth required onerr=fail deny=5
account required

This should make sure that accounts are locked if the number of failed attempts exceeds 5. The counter is reset on successful login.

The behaviour of pam_tally has changed over time – this approach should work on at least Fedora Core 6+, RHEL 5, SLES10 and later.

In SLES 10 the PAM config-file is /etc/pam.d/login