NAME tripwire - a file integrity checker for UNIX systems SYNOPSIS tripwire [ options ... ] DESCRIPTION Tripwire is a file integrity checker - a utility that compares a designated set of files and directories against information stored in a previously generated database. Added or deleted files are flagged and reported, as are any files that have changed from their previously recorded state in the database. When run on a regular basis, Tripwire is a useful tool for maintaining the integrity of system files. If unauthorized changes are discovered, Tripwire can quickly determine the extent of the problem, allowing system administrators to enact damage control measures. Using Tripwire, system administrators can conclude with an extremely high degree of certainty that a given set of files and directories have not been modified, provided the tripwire program and database are appropriately protected (e.g., stored on read-only media). Tripwire uses message- digest algorithms (one-way hash functions) to detect changes in a hard-to-spoof manner. These algorithms are designed to detect even the smallest changes to files, including changes caused by insertion of backdoors or viruses. Tripwire can be configured to monitor changes to file permissions, modification times, and other significant inode changes on a per-file/directory basis. Changes are reported relative to the last Tripwire database installation or update. Tripwire runs in one of four modes: Database Generation, Integrity Checking, Database Update, or Interactive Update mode. In Database Generation mode, Tripwire initializes the database based on the entries enumerated in the tw.config file. The Integrity Checking mode compares all of the files described by the tw.config file against the files residing on the filesystem to generate a list of added, deleted, or changed files. Database Update mode allows the user to update individual file or directory entries in the database, rather than regenerating the entire database every time a file or set of files change. The Interactive Update mode combines the functions of the Integrity Checking and Database Update modes. Interactive Update mode reports added, deleted, and changed files and gives the user the option to update each affected database entry individually. Interactive Update provides a simple and thorough method for system administrators to keep Tripwire databases ``in sync'' with changing filesystems. OPTIONS When run without any arguments, tripwire runs in Integrity Checking mode. -initialize, --init, --initialize Database Generation mode. Creates the database which is used for all subsequent Integrity Checking runs. -update [[pathname|entry] ...], -- update [[pathname|entry] ...] Database Update mode. This mode updates the specified pathname or entry in the database. If the argument provided is a file, only that file is updated. If the argument is a directory, that directory and all of its children are updated. If the argument is an entry in the tw.config file, the entire entry in the database is updated. -interactive, --interactive Interactive Update mode. Tripwire first reports all added, deleted, and changed files, then allows the user to update the entry in the database. Note that Tripwire opens up /dev/tty instead of using stdin. This prevents the automation of interactive updates, reducing the chance of system administrators inadvertently updating entries. Updating the database should always be done with care and deliberation. -loosedir, --loose-directory-checking Loosens checking criteria for directories in Integrity Checking or Interactive Update modes so changes in size, nlink, modification and creation times are no longer reported. This significantly quiets Tripwire reports, at the possible risk of missing important changes. -d dbasefile, --dbfile dbasefile Reads the database information from the specified dbasefile. stdin can be specified using ``-d -'' or ``--dbfile -''. -c configfile, --cfgfile configfile Read the configuration information from the specified configfile. stdin can be specified using ``-c -'' or ``--cfgfile -''. -cfd openfd Read the configuration information from the open file descriptor openfd. This option allows programs outside of Tripwire to supply services such as networking, compression, and encryption. -dfd openfd Read the database file from the open file descriptor openfd. This option allows programs outside of Tripwire to supply services such as networking, compression, and encryption. -Dvar=value Defines the tw.config variable var to value, as if @@define were used. -Uvar Undefine the tw.config variable var, as if @@undef were used. -i [#|all], --ignore [#|all] Ignore the specified signature, and skip it when comparing against database entries. If all is specified, no signatures are collected or compared. -x, --print-hex Collect and display all signature values in hexadecimal, rather than base64 notation. -E, -preprocess Prints out preprocessed tw.config file to stdout. -q, --quiet, --silent Quiet mode. In this mode, Tripwire displays only one line of text for each added, changed, or deleted file. Phase 5 of the Tripwire report, which prints the pairs of expected and observed file attribute values, is omitted. -v, --verbose Verbose mode. Prints out filenames as they are being scanned during signature computation. -help [inode], --help [inode] Prints out usage information. If "inode" is specified as an argument, this command will instead print an inode interpretation message (for parsing messages when files have changed). -version, --version Prints out version information. DATABASE GENERATION MODE In Database Generation mode, tripwire creates the database file based on the entries in tw.config. The name of this database file is defined at compile-time in config.h - the default name is tw.db_[hostname]. The generated database is placed in the ./databases directory, and must be moved to the target directory manually. Note that you must manually move this file to the directory specified in config.h because the default database directory should be a read-only file system. INTEGRITY CHECKING MODE In Integrity Checking mode, tripwire reads in the tw.config file and builds a new database to reflect the state of current files. Tripwire then compares the new database with the existing database and reports added, deleted, or changed files. The tw.config file enumerates the files and directories that Tripwire watches, with select-flags for each listing the attributes for that file that should and should not change. Tripwire applies these rules to determine which changes should be reported after an integrity check. Tripwire detects all changes to entries in the tw.config file, but only those changes specified by the select-flags for that entry are displayed after an integrity check. For each of these changes, the expected value (from the database) and the actual information (observed in the file) are printed. For example: 2:30am (mentor) 985 % tripwire ### Phase 1: Reading configuration file ### Phase 2: Generating file list ### Phase 3: Creating file information database ### Phase 4: Searching for inconsistencies ### ### Total files scanned: 82 ### Files added: 0 ### Files deleted: 0 ### Files changed: 80 ### ### After applying rules: ### Changes discarded: 79 ### Changes remaining: 1 ### changed: -rw------- 4433 Oct 13 02:30:34 1992 /tmp/config.h ### Phase 5: Generating observed/expected pairs for changed files ### ### Attr Observed (what it is) Expected (what it should be) ### =========== ============================= ============================= /tmp/config.h st_size: 4441 4433 md5 (sig1): 0aqL1O06C3Fj1YBXz3.CPdcb 0cPX1H.DYS.s1vZdKD.ELMDR snefru (sig2): 0PcgcK/MZvEm.8pIWe.Gbnn/ /8VoJv1JcoUA0NvoGN.k3P6E crc32 (sig3): .EHA6x /OuGNV crc16 (sig4): ...9/q ...6yu md4 (sig5): /hQ0sU.UEbJo.UR4VZ/mNG/h .UR4VZ/mNG/h/VSG/W/Z643k md2 (sig6): .hLwjb.VRA0O.Z72y90xTYqA 1LR0Gg1l.vqB0.1g330Pi8/p DATABASE UPDATE MODE In Database Update mode, tripwire updates database information for specified files, directories, or tw.config entries. This mode allows the user to update a Tripwire database to reflect filesystem changes, rather than regenerating the entire database every time a file or set of files change. The new, updated database is written to the ./databases directory. The old database is also saved in the ./databases directory, with the .old suffix added. As in the Database Generation mode, the new database must be manually moved to the Tripwire database directory. The tripwire Database Update mode requires at least one argument, specifying the file or directory to be updated. If the argument is a filename, only that file is updated in the database. If the argument is a directory name, the directory and its children are updated. If the argument is also an entry in the tw.config file, the entire entry is updated. INTERACTIVE UPDATE MODE tripwire Interactive Update mode produces output that is very similar to the output from Integrity Checking mode (see example, above). However, for each addition, deletion, or change detected during an integrity check, the user is given the option to update the database information for the corresponding file or directory. Possible responses are ``y'', ``n'', ``Y'', or ``N''. The first two responses are simply ``yes, update the specified file or directory'' and ``no, don't update the file or directory'', respectively. Answering ``Y'' updates the specified file or directory and all other files or directories that share the same entry in the tw.config file. For example, if ``Y'' were answered for /etc, then all the files generated by the /etc entry will also be updated. Answering ``N'' will suppress updating for all files and directories corresponding to the specified entry. A Tripwire session running in Interactive Update mode might look like: 3:34pm (flounder) tw/src 5 %%% tripwire -interactive ### Phase 1: Reading configuration file ### Phase 2: Generating file list ### Phase 3: Creating file information database ### Phase 4: Searching for inconsistencies ### ### Total files scanned: 49 ### Files added: 0 ### Files deleted: 0 ### Files changed: 49 ### ### After applying rules: ### Changes discarded: 48 ### Changes remaining: 1 ### changed: -rw------- 7893 May 5 15:30:37 1993 /homes/research/tw/src/databases/tw.db_flounder.Eng.Sun.COM.old ### Phase 5: Generating observed/expected pairs for changed files ### ### Attr Observed (what it is) Expected (what it should be) ### =========== ============================= ============================= /homes/research/tw/src/databases/tw.db_flounder.Eng.Sun.COM.old st_mtime: Wed May 5 15:30:37 1993 Wed May 5 15:24:09 1993 st_ctime: Wed May 5 15:30:37 1993 Wed May 5 15:24:09 1993 ---> File: '/homes/research/tw/src/databases/tw.db_flounder.Eng.Sun.COM.old' ---> Update entry? [YN(y)nh?] y ### Updating database... ### ### Phase 1: Reading configuration file ### Phase 2: Generating file list ### Phase 3: Updating file information database ### Phase 3: Updating file information database ### ### Old database file will be moved to `tw.db_barnum.cs.purdue.edu.old' ### in ./databases. ### ### Updated database will be stored in './databases/tw.db_barnum.cs.purdue.edu' ### (Tripwire expects it to be moved to '/tmp/'.) ### 3:34pm (flounder) tw/src 6 %%% DIAGNOSTICS Tripwire exit status is 1 for any error condition. Otherwise, the exit status is the logical OR'ing of the following: 2 for files added, 4 for files deleted, and 8 for files changed. For instance, if Tripwire exits with status code 10, then files were added and changed (8 + 2 = 10). ENVIRONMENT None. BUGS This manual page is not self-contained - users are referred to the Tripwire design document designdoc.ps for more information on the issues of integrity checking. SEE ALSO tw.config(5) The Design and Implementation of Tripwire: A UNIX File Integrity Checker by Gene Kim and Eugene Spafford. Purdue Technical Report CSD-TR-93-071. AUTHORS Gene Kim Tripwire Security Systems, Inc. [email protected] Eugene Spafford Purdue University [email protected]
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