Configuration File

default: /usr/local/etc/tripwire/tw.cfg
The configuration file stores system-specific information, such as the location of Tripwire data files. The configuration settings are generated during the installation process, but can be changed by the system administrator at any time. See the twconfig(4) man page for a more complete discussion.

Policy File

default: /usr/local/etc/tripwire/tw.pol
The policy file consists of a series of rules specifying the system objects that Tripwire should monitor, and the data for each object that should be collected and stored in the database file. Should unexpected changes occur, the policy file can describe the person to be notified and the severity of the violation. See the policyguide.txt file in the policy directory and the twpolicy(4) man page for a more complete discussion.

Database File

default: /var/lib/$(HOSTNAME).twd
The database file serves as the baseline for integrity checking. After installation, Tripwire creates the initial database file, a "snapshot" of the filesystem in a known secure state. Later, when an integrity check is run, Tripwire compares each system object described in the policy file against its corresponding entry in the database. A report is created, and if an object has changed outside of constraints defined in the policy file, a violation is reported. See the tripwire(8) and twprint(8) man pages for more information on creating and maintaining database files.

Report Files

default: /var/lib/tripwire/report/$(HOSTNAME)‐$(DATE).twr
Once the above three files have been created, Tripwire can run an integrity check and search for any differences between the current system and the data stored in the "baseline" Tripwire database. This information is archived into report files, a collection of rule violations discovered during an integrity check. With the appropriate settings, a report can also be emailed to one or more recipients. See the tripwire(8) and twprint(8) man pages for information on creating and printing report files.

Key Files

defaults: /usr/local/etc/tripwire/site.key and /usr/local/etc/tripwire/$(HOSTNAME)‐local.key
It is critical that Tripwire files be protected from unauthorized access‐‐an attacker who is able to modify these files can subvert Tripwire operation. For this reason, all of the above files are signed using public key cryptography to prevent unauthorized modification. Two separate sets of keys protect critical Tripwire data files. One or both of these key sets is necessary for performing almost every Tripwire task.

The site key is used to protect files that could be used across several systems. This includes the policy and configuration files. The local key is used to protect files specific to the local machine, such as the Tripwire database. The local key may also be used for signing integrity check reports. See the twadmin(8) man page for more information on keys.

File Backup

To prevent the accidental deletion of important data, Tripwire automatically creates backup files whenever any Tripwire file is overwritten. The existing file will be renamed with a .bak extension, and the new version of the file will take its place. Only one backup copy for each filename can exist at any time. If a backup copy of a file already exists, the older backup file will be deleted and replaced with the newer one.

File backup is an integral part of Tripwire, and cannot be removed or changed.