Cryptography

Change user password automatically

There are several way to change user password automatically.

  • Use usermod -p or useradd -p. It accepts a encrypted password. You can use the following commands to generate one:

    # encpasswd=`openssl passwd -1 foo`
# encpasswd=`perl -e 'print(crypt("foo","salt"),"\n")'`
# usermod -p $encpasswd bar
# useradd -p $encpasswd bar

  • Use passwd --stdin to set an user's password:

    # echo "foo" | passwd --stdin bar

Change virtual machine password in a image file

Use this script chpasswd.sh:

#!/bin/bash

# Stefan de Konink <dekonink@kinkrsoftware.nl>
# Licensed under the GPL v3 or in your opinion any later version
#
# Usage: chpasswd.sh <imagefile> <passwd>

DIR=/tmp/$(basename $1)
mkdir $DIR
mount -o loop $1 $DIR
chroot $DIR /usr/sbin/chpasswd <<EOF
root:$2
EOF
umount $DIR
rmdir $DIR

Do it:

# ./chpasswd.sh system.img new-root-passwd

Cryptography (last edited 2009-08-13 07:48:11 by ZhigangWang)