checkpw

checkpw is a program that checks the validity of a users password on a UNIX/PAM-based system.

Currently checkpw is only tested on Linux, but it should work on a AIX, DragonFly BSD, FreeBSD, HP-UX, Linux, macOS, NetBSD and Solaris operating system too.

The idea

I needed a program to verify passwords of users on Linux/UNIX systems using PAM that just returns 0 on success and 1 on error.

Building checkpw

git clone https://git.xw3.org/xw3/checkpw.git
cd checkpw
make

The code only supports verifying passwords for user id 1000 by default. Look at the file checkpw.h for some compile time options!

Custom build example

Set MAX_UID and MIN_UID at compile time:

gcc -Wall -DMAX_UID=1000 -DMIN_UID=1000 -o checkpw checkpw.c -lpam -lpam_misc

Installation

WARNING: Install this software with care. checkpw could easily be used for bruteforcing passwords from local users!

sudo make install

checkpw is installed to /usr/bin/.

checkpw.h is installed to /usr/include/ for use in other applications.

Uninstall

sudo make uninstall

Usage

checkpw -h
Usage: checkpw [-u <username>] [-p <password>] [-v] [-V] [-h]

Options:
  -u <username>  Set username.
  -p <password>  Set password.
  -v             Enable verbose mode.
  -V             Print program version.
  -h             Show this help.

You can also use checkpw even without installing by just running the following command:

./checkpk

checkpw returns 0 on success, 1 otherwise.

Examples

Interactive mode asking for a username and a password

checkpw

Interactive mode only asking for a password

checkpw -u hanez

None interactive mode with username and password provided as arguments to checkpw

checkpw -u hanez -p password

Request the result from the above commands

echo $?

License

checkpw is licensed under the Apache License, Version 2.0.

See LICENSE for details.

Links

• Homepage of checkpw
• https://cr.yp.to/checkpwd.html
• https://pamtester.sourceforge.net/