ausearch.8 - Online Linux Manual Page

AUSEARCH - Online Linux Manual PageSection : 8
Updated : February 2023
Source : Red Hat
Note : System Administration Utilities

NAMEausearch − a tool to query audit daemon logs

SYNOPSISausearch [options]

DESCRIPTIONausearch is a tool that can query the audit daemon logs based for events based on different search criteria. The ausearch utility can also take input from stdin as long as the input is the raw log data. Each commandline option given forms an "and" statement. For example, searching with −m and −ui means return events that have both the requested type and match the user id given. An exception is the −m and −n options; multiple record types and nodes are allowed in a search which will return any matching node and record. It should also be noted that each syscall excursion from user space into the kernel and back into user space has one event ID that is unique. Any auditable event that is triggered during this trip share this ID so that they may be correlated. Different parts of the kernel may add supplemental records. For example, an audit event on the syscall "open" will also cause the kernel to emit a PATH record with the file name. The ausearch utility will present all records that make up one event together. This could mean that even though you search for a specific kind of record, the resulting events may contain SYSCALL records. Also be aware that not all record types have the requested information. For example, a PATH record does not have a hostname or a loginuid.

OPTIONS−a, −−event audit-event-id Search for an event based on the given event ID. Messages always start with something like msg=audit(1116360555.329:2401771). The event ID is the number after the ':'. All audit events that are recorded from one application's syscall have the same audit event ID. A second syscall made by the same application will have a different event ID. This way they are unique. −−arch CPU Search for events based on a specific CPU architecture. If you do not know the arch of your machine but you want to use the 32 bit syscall table and your machine supports 32 bits, you can also use b32 for the arch. The same applies to the 64 bit syscall table, you can use b64. The arch of your machine can be found by doing 'uname -m'. −c, −−comm comm-name Search for an event based on the given comm name. The comm name is the executable's name from the task structure. −−debug Write malformed events that are skipped to stderr. −−checkpoint checkpoint-file Checkpoint the output between successive invocations of ausearch such that only events not previously output will print in subsequent invocations. An auditd event is made up of one or more records. When processing events, ausearch defines events as either complete or in-complete. A complete event is either a single record event or one whose event time occurred 2 seconds in the past compared to the event being currently processed. A checkpoint is achieved by recording the last completed event output along with the device number and inode of the file the last completed event appeared in checkpoint-file. On a subsequent invocation, ausearch will load this checkpoint data and as it processes the log files, it will discard all complete events until it matches the checkpointed one. At this point, it will start outputting complete events. Should the file or the last checkpointed event not be found, one of a number of errors will result and ausearch will terminate. See EXIT STATUS for detail. −−eoe−timeout seconds Set the end of event parsing timeout. See end_of_event_timeout in auditd.conf(5) for details. Note that setting this value will override any configured value found in /etc/auditd/auditd.conf. −e, −−exit exit-code-or-errno Search for an event based on the given syscall exit code or errno. −−escape option This option determines if the output is escaped to make the content safer for certain uses. The options are raw , tty , shell , and shell_quote. Each mode includes the characters of the preceding mode and escapes more characters. That is to say shell includes all characters escaped by tty and adds more. tty is the default. −−extra-keys When the format mode is csv, this option will add a final column with key information if its exists for the event. This would only occur on SYSCALL records which were the result of triggering an audit rule that defines a key. −−extra-labels When the format mode is csv, this option will add columns of information about subject and object labels when they exist. −−extra-obj2 When the format mode is csv, this option will add columns of information about a second object when it exists. It's rare that a second object is part of a record. Some examples are when a file is renamed from one name to another or when a device is mounted to a path. −−extra-time When the format mode is csv, this option will add columns of information about broken down time to make subsetting easier. −f, −−file file-name Search for an event based on the given filename. The argument will match normal files as well as af_unix sockets. −−format option Events that match the search criteria are formatted using this option. The supported formats are: raw, default, interpret, csv, and text. The raw option is described under the −−raw command line option. The default option is what you get when no formatting options are passed. It includes one line as a visual separator which indicates the time stamp and then the records of the event follow. The interpret option is explained under the −i command line option. The csv option outputs the results of the search as a normalized event in comma separated value (CSV) format suitable for import into analytical programs. The text option turns the event into an English sentence that is easier to understand than other options, but it comes at the expense of loss of detail. In most cases this is perfectly fine since the original event still retains all the original information. −ga, −−gid−all all-group-id Search for an event with either effective group ID or group ID matching the given group ID. −ge, −−gid−effective effective-group-id Search for an event with the given effective group ID or group name. −gi, −−gid group-id Search for an event with the given group ID or group name. −h, −−help Help −hn, −−host host-name Search for an event with the given host name. The hostname can be either a hostname, fully qualified domain name, or numeric network address. No attempt is made to resolve numeric addresses to domain names or aliases. This search typically correlates to the addr or host field of audit events. Also see the −−node command which searches the node field. −i, −−interpret Interpret numeric entities into text. For example, uid is converted to account name. If the audit logs are unenriched, the conversion is done using the current resources of the machine where the search is being run. If you have renamed the accounts, or don't have the same accounts on your machine, you could get misleading results. If the logs are enriched, it uses the supplemental data to do the conversion. This allows accurate log reporting even when run on a different machine than the original logs came from. −if, −−input file-name | directory Use the given file or directory instead of the logs. This is to aid analysis where the logs have been moved to another machine or only part of a log was saved. The path length is limited to 4064 bytes. −−input−logs Use the log file location from auditd.conf as input for searching. This is needed if you are using ausearch from a cron job. −−just−one Stop after emitting the first event that matches the search criteria. −k, −−key key-string Search for an event based on the given key string. −l, −−line−buffered Flush output on every line. Most useful when stdout is connected to a pipe and the default block buffering strategy is undesirable. May impose a performance penalty. −m, −−message message-type | comma-sep-message-type-list Search for an event matching the given message type. (Message types are also known as record types.) You may also enter a comma separated list of message types or multiple individual message types each with its own -m option. There is an ALL message type that doesn't exist in the actual logs. It allows you to get all messages in the system. The list of valid messages types is long. The program will display the list whenever no message type is passed with this parameter. The message type can be either text or numeric. If you enter a list, there can be only commas and no spaces separating the list. −n, −−node Search for events originating from a specific machine. Multiple nodes are allowed, and if any nodes match, the event is matched. This search uses the node field in audit events. Also see the −−host command which search for events related to host information in the audit trail. −o, −−object SE-Linux-context-string Search for event with tcontext (object) matching the string. −p, −−pid process-id Search for an event matching the given process ID. −pp, −−ppid parent-process-id Search for an event matching the given parent process ID. −r, −−raw Output is completely unformatted. This is useful for extracting records to a file that can still be interpreted by audit tools or when piping to other audit tools. −sc, −−syscall syscall-name-or-value Search for an event matching the given syscall. You may either give the numeric syscall value or the syscall name. If you give the syscall name, it will use the syscall table for the machine that you are using. −se, −−context SE-Linux-context-string Search for event with either scontext/subject or tcontext/object matching the string. −−session Login-Session-ID Search for events matching the given Login Session ID. This process attribute is set when a user logs in and can tie any process to a particular user login. −su, −−subject SE-Linux-context-string Search for event with scontext (subject) matching the string. −sv, −−success success-value Search for an event matching the given success value. Legal values are yes and no. −te, −−end [end-date] [end-time] Search for events with time stamps equal to or before the given end time. The format of end time depends on your locale. You can check the format of your locale by running date '+%x'. If the date is omitted, today is assumed. If the time is omitted, now is assumed. Use 24 hour clock time rather than AM or PM to specify time. An example date using the en_US.utf8 locale is 09/03/2009. An example of time is 18:00:00. The date format accepted is influenced by the LC_TIME environmental variable. You may also use the word: now, recent, this-hour, boot, today, yesterday, this−week, week−ago, this−month, or this−year. Now means starting now. Recent is 10 minutes ago. Boot means the time of day to the second when the system last booted. Today means now. Yesterday is 1 second after midnight the previous day. This−week means starting 1 second after midnight on day 0 of the week determined by your locale (see localtime). Week−ago means 1 second after midnight exactly 7 days ago. This−month means 1 second after midnight on day 1 of the month. This−year means the 1 second after midnight on the first day of the first month. −ts, −−start [start-date] [start-time] Search for events with time stamps equal to or after the given start time. The format of start time depends on your locale. You can check the format of your locale by running date '+%x'. If the date is omitted, today is assumed. If the time is omitted, midnight is assumed. Use 24 hour clock time rather than AM or PM to specify time. An example date using the en_US.utf8 locale is 09/03/2009. An example of time is 18:00:00. The date format accepted is influenced by the LC_TIME environmental variable. You may also use the word: now, recent, this-hour, boot, today, yesterday, this−week, week−ago, this−month, this−year, or checkpoint. Boot means the time of day to the second when the system last booted. Today means starting at 1 second after midnight. Recent is 10 minutes ago. Yesterday is 1 second after midnight the previous day. This−week means starting 1 second after midnight on day 0 of the week determined by your locale (see localtime). Week−ago means starting 1 second after midnight exactly 7 days ago. This−month means 1 second after midnight on day 1 of the month. This−year means the 1 second after midnight on the first day of the first month. checkpoint means ausearch will use the timestamp found within a valid checkpoint file ignoring the recorded inode, device, serial, node and event type also found within a checkpoint file. Essentially, this is the recovery action should an invocation of ausearch with a checkpoint option fail with an exit status of 10, 11 or 12. It could be used in a shell script something like: ausearch --checkpoint /etc/audit/auditd_checkpoint.txt -i _au_status=$? if test ${_au_status} eq 10 -o ${_au_status} eq 11 -o ${_au_status} eq 12 then ausearch --checkpoint /etc/audit/auditd_checkpoint.txt --start checkpoint -i fi −tm, −−terminal terminal Search for an event matching the given terminal value. Some daemons such as cron and atd use the daemon name for the terminal. −ua, −−uid−all all-user-id Search for an event with either user ID, effective user ID, or login user ID (auid) matching the given user ID. −ue, −−uid−effective effective-user-id Search for an event with the given effective user ID. −ui, −−uid user-id Search for an event with the given user ID. −ul, −−loginuid login-id Search for an event with the given login user ID. All entry point programs that are PAMified need to be configured with pam_loginuid required for the session for searching on loginuid (auid) to be accurate. −uu, −−uuid guest-uuid Search for an event with the given guest UUID. −v, −−version Print the version and exit −vm, −−vm-name guest-name Search for an event with the given guest name. −w, −−word String based matches must match the whole word. This category of matches include: filename, hostname, terminal, keys, and SE Linux context. −x, −−executable executable Search for an event matching the given executable name.

EXIT STATUS0 if OK, 1 if nothing found, or argument errors or minor file access/read errors, 10 invalid checkpoint data found in checkpoint file, 11 checkpoint processing error 12 checkpoint event not found in matching log file

NOTEThe boot time option is a convenience function and has limitations. The time it calculates is based on time now minus /proc/uptime. If after boot the system clock has been adjusted, perhaps by ntp, then the calculation may be wrong. In that case you'll need to fully specify the time. You can check the time it would use by running: date -d "`cut −f1 −d. /proc/uptime` seconds ago"

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