7.5 KiB
Open Source Tripwire®
Open Source Tripwire® software is a security and data integrity tool useful for monitoring and alerting on specific file change(s) on a range of systems. The project is based on code originally contributed by Tripwire, Inc. in 2000.
Open Source Tripwire is suitable for monitoring a small number of servers, where centralized control and reporting is not needed and professional support or system automation is not a requirement.
Overview
A tripwire check compares the current filesystem state against a known baseline state, and alerts on any changes it detects. The baseline and check behavior are controlled by a policy file, which specifies which files or directories to monitor, and which attributes to monitor on them, such as hashes, file permissions, and ownership.
When a desired change occurs, such as upgrading a package, the baseline database can be updated to the new known-good state. The policy can also be updated, for example to reduce noise or cover a newly installed package.
Getting Started
This section covers manual setup of Open Source Tripwire. If you're installing from an RPM or Debian package, or via "make install", a setup script will walk you through the initial setup steps and these will not need to be done by hand.
Generating Keys
The first step is to generate site and local key files. This is necessary because Tripwire policy, configuration, and database files are signed by default, and report files may also be signed. The site key is used to sign config and policy files, with the idea that multiple machines will share a site key, but each will have its own local key. The policy and config files can then be created once and distributed across these machines.
A common practice is to include the hostname in the local key filename, as follows:
./twadmin --generate-keys -L /etc/tripwire/${HOSTNAME}-local.key
./twadmin --generate-keys -S /etc/tripwire/site.key
Creating a configuration file
The next step is to create a tripwire config file. The config file contains a variety of settings including the locations of tripwire binaries and key files, email report settings, and parameters that control baseline/check behavior. These settings are explained in detail in the twconfig(4) manual page.
This command line creates the config text in /etc/tripwire/twcfg.txt, validates and signs it with the site key file, and writes the results to /etc/tripwire/tw.cfg:
./twadmin --create-cfgfile -S /etc/tripwire/site.key /etc/tripwire/twcfg.txt
Generating a policy file
Now it's time to configure OST for what you want to monitor. A few simple examples of policy rules:
/start/point -> $(IgnoreNone); # Get all attributes for this dir tree
/another/start -> +pinugS; # Get selected attributes for this dir tree
!/start/point/subdir/to/ignore; # Don't monitor this dir tree
The tripwire policy language is documented in detail in the twpolicy(4) manual page, and default policies for several popular operating systems are available in the OST project's policy subdirectory.
./twadmin --create-polfile -S /etc/tripwire/twpol.txt
Baselining your system
Now you're ready to baseline the system for the first time.
tripwire --init
This creates a database file in the configured directory, typically a file with a .twd extension /var/lib/tripwire. The optional "--verbose" argument to init mode lists files and directories as they're being scanned.
Running a check
tripwire --check
This runs a check, again with an optional "--verbose" option that explains what it's doing. Scan results are written to standard out, as well as a report file, which typically has a .twr extension and lives in /var/lib/tripwire/report. If email reporting is enabled, emails will be sent at the end of the check.
Printing a report
twprint -m r -r /path/to/reportfile.twr
Databases can be also printed with
twprint -m d -d /path/to/database.twd
Updating a database
The simplest form of update updates the database with all the changes in a report file:
tripwire --update --accept-all
While a
tripwire --update
brings up a text report in the user's preferred editor (as configured in the config file), wich a checkbox next to each detected change. If you save and exit the editor, the database will only be updated for those objects that remain selected with an [x].
Updating a policy
TODO
Testing the email configuration
TODO
Building OST
Prerequisites
A C++ compiler. It's known to build with gcc and clang; OST should work with gcc versions as old as 2.95.2, although gcc older than version 3.1 will need an external STLPort package.
A POSIX-like operating system. TODO: list
Perl 5 [what version?] to run the project's test suite.
Configuring & Building
OST uses a fairly standard automake build, such that your first step will generally be:
./configure
Different paths, compiler args (like Debian hardening options), non-default locations can be set up in this step.
[give some common configure options here]
You might need to run the script
./touchconfig.sh```
before you're able to build the project. The script simply touches files in the right order so files' last change times are not all identical, and that they're different in the right order.
Then just
make``` to build the project.
Running the test suites
the "make check" make target runs two things: The test harness suite in the src/test-harness directory, and unit tests by running twtest, which is built in the bin directory along with other tripwire binaries. These tests can also be run separately:
./twtest
runs all unit tests, while
./twtest list
lists all available tests.
./twtest Groupname
runs all tests in a group, and
./twtest Groupname/Testname
just runs the specified test.
[ TODO: how to run test-harness tests ]
Deployment
The "make install" target installs OST to the configured location, and "make install-strip" installs and removes symbols from the tripwire binaries. A "make dist" creates a gzipped source bundle.
Authors
License
The developer of the original code and/or files is Tripwire, Inc. Portions created by Tripwire, Inc. are copyright 2000-2018 Tripwire, Inc. Tripwire is a registered trademark of Tripwire, Inc. All rights reserved.
This program is free software. The contents of this file are subject to the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. You may redistribute it and/or modify it only in compliance with the GNU General Public License.
This program is distributed in the hope that it will be useful. However, this program is distributed "AS-IS" WITHOUT ANY WARRANTY; INCLUDING THE IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please see the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Nothing in the GNU General Public License or any other license to use the code or files shall permit you to use Tripwire's trademarks, service marks, or other intellectual property without Tripwire's prior written consent.
If you have any questions, please contact Tripwire, Inc. at either info@tripwire.org or www.tripwire.org.