Open Source Tripwire is a free software security and data integrity tool for monitoring and alerting on specific file change(s) on a range of systems[2][3] originally developed by Eugene H. Spafford and Gene Kim.

[2] The Tripwire was created by Dr. Eugene Spafford and Gene Kim in 1992 in response to a series of stealthy intrusions that occurred in early 1991.

These attacks circumvented the existing security systems by infecting the shared libraries in a way that their CRC checksums were unchanged.

Open Source Tripwire was released in October, 2000,[6] under the GNU General Public License.

[10] During the installation, Open Source Tripwire asks the user to set the site-key and local key passphrases.

The site-key passphrase encrypts the policy and configuration files which are shared across multiple systems.

[2] Open Source Tripwire later asks for the local passphrase when creating an initial database with file signatures.

[3] Open Source Tripwire can be configured to regularly run integrity checks and send report e-mails to the system administrator.

When the intruder reads these files, their access timestamps get updated and the security administrators get notified about this incident.

[9]: 13–15 In order to minimize the impact of hash collisions (i.e. the signature would not change even when the file was changed) on the security, Tripwire uses multiple different hashing algorithms to compute multiple signatures for each file.

[9]: 7,15  Tripwire provides a generic interface to signature routines, so the user can include their own checksum methods.