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Google Authenticator PAM module vs OATH Toolkit: catalog facts
Google Authenticator PAM module	OATH Toolkit
Free Free and open source under the Apache-2.0 license.	Free Free software; tools use GPL-3.0-or-later and libraries use LGPL-2.1-or-later.
Linux, Command line	Command line
Supports HOTP and TOTP Works with PAM logins such as SSH and OpenVPN	Generates and validates HOTP and TOTP codes Includes tools for managing PSKC data
Requires configuration in the system's PAM setup.	The tools use GPLv3-or-later and the libraries use LGPLv2-or-later.
Downloadable app	Downloadable app
Open source	Open source
License: Apache-2.0	License: GPL-3.0-or-later AND LGPL-2.1-or-later
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 8, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.