How to add a user without knowing the encrypted form of the password?

Question

I use the following command to create a user in a linux machine:

useradd -d /home/dummy -g idiots -m -p 12345689 dummy

The user is created and the home directory as well.
The problem is that I can not log-in to the system using this account since the -p expects the encrypted password returned by crypto.

Question:I want to create a user via a bash script and I don't know the encrypted password by crypto. How can I do it so that I am able to create this user automatically via a script and get arround the problem with the password?

Answer 1

You can use openssl to generate pre encrypted password strings to use with the -p option to useradd

echo "P4sSw0rD" | openssl passwd -1 -stdin

$1$Jxmpx1Da$Y8MzBctIyDW8/7pFPbNWD1

The -1 says to generate a MD5 password hash. The salt is automatically generated.

You can then use

useradd -d /home/dummy -g idiots -m -p $(echo "P4sSw0rD" | openssl passwd -1 -stdin) dummy

to add the user. To do this interactively hiding the password

useradd -d /home/dummy -g idiots -m -p $(read -sp Password: pw ; echo $pw | openssl passwd -1 -stdin) dummy

Answer 2

Apparently, you can use

echo "password" | passwd dummy --stdin

I've never tried this.

Alternatively, you could put the user's public key in /home/dummy/.ssh/authorized_keys and forget about passwords entirely. This is the best option security-wise.

Answer 3

That`s how I do it:

# cat user-pw_list
john:p455W0rD
geany:p455W0rD


# cat CreateUsers.sh
#!/bin/bash
#
# filename: CreateUsers.sh
# usage: cat "User:passwd" | $0
#
set -e
# set -x
while read ; do
  USER=${REPLY%%:*}
  PWD=${REPLY##*:}
  # alternative for random passwd, where $RANDOM is a bash function
  #PWD=${REPLY%%:*}$RANDOM$RANDOM

  echo -e "adding User $USER "
  # for disabled users: /usr/sbin/nologin, otherwise /bin/bash
  /usr/sbin/useradd -c automaticUser -m -k/dev/null -s /usr/sbin/nologin $USER
  echo "$USER:$PWD" | chpasswd --md5 $USER

  ## also add user to samba:
  #echo -e "$PWD\n$PWD" | pdbedit -t -u $USER
done

Answer 4

As you are going to use a bash script, perhaps the good old newusers command would be helpful to you? It reads its input from a text file formatted like this:

pw_name:pw_passwd:pw_uid:pw_gid:pw_gecos:pw_dir:pw_shell

And the password in that file should be clear text. You can list as many users as you wish in the input file.

For more information see man newusers.