rkhunter
rkhunter(8) System Manager's Manual rkhunter(8)
NAME
rkhunter - RootKit Hunter
SYNOPSIS
rkhunter {--check | --unlock | --update | --versioncheck |
--propupd [{filename | directory | package name},...] |
--list [tests | {lang | languages} | rootkits | perl |
propfiles] |
--config-check | --version | --help} [options]
DESCRIPTION
rkhunter is a shell script which carries out various checks on the lo-
cal system to try and detect known rootkits and malware. It also per-
forms checks to see if commands have been modified, if the system
startup files have been modified, and various checks on the network in-
terfaces, including checks for listening applications.
rkhunter has been written to be as generic as possible, and so should
run on most Linux and UNIX systems. It is provided with some support
scripts should certain commands be missing from the system, and some of
these are perl scripts. rkhunter does require certain commands to be
present for it to be able to execute. Additionally, some tests require
specific commands, but if these are not present then the test will be
skipped. rkhunter needs to be run under a Bourne-type shell, typically
bash or ksh. rkhunter can be run as a cron job or from the com-
mand-line.
COMMAND OPTIONS
If no command option is given, then --help is assumed. rkhunter will
return a non-zero exit code if any error or warning occurs.
-c, --check
This command option tells rkhunter to perform various checks on
the local system. The result of each test will be displayed on
stdout. If anything suspicious is found, then a warning will be
displayed. A log file of the tests and the results will be auto-
matically produced.
It is suggested that this command option is run regularly in or-
der to ensure that the system has not been compromised.
--unlock
This command option simply unlocks (removes) the lock file. If
this option is used on its own, then no log file is created.
--update
This command option causes rkhunter to check if there is a later
version of any of its text data files. A command-line web
browser, for example wget or lynx, must be present on the system
when using this option.
It is suggested that this command option is run regularly in or-
der to ensure that the data files are kept up to date.
If this option is used via cron, then it is recommended that the
--nocolors option is also used.
An exit code of zero for this command option means that no up-
dates were available. An exit code of one means that a download
error occurred, and a code of two means that no error occurred
but updates were available and have been installed.
--propupd [{filename | directory | package name},...]
One of the checks rkhunter performs is to compare various cur-
rent file properties of various commands, against those it has
previously stored. This command option causes rkhunter to update
its data file of stored values with the current values.
If the filename option is used, then it must either be a full
pathname, or a plain file name (for example, 'awk'). When used,
then only the entry in the file properties database for that
file will be updated. If the directory option is used, then only
those files listed in the database that are in the given direc-
tory will be updated. Similarly, if the package name option is
used, then only those files in the database which are part of
the specified package will be updated. The package name must be
the base part of the name, no version numbers should be included
- for example, 'coreutils'. Package names will, of course, only
be stored in the file properties database if a package manager
is being used. If a package name is the same as a file name -
for example, 'file' could refer to the 'file' command or to the
RPM 'file' package (which contains the 'file' command) - the
package name will be used. If no specific option is given, then
the entire database is updated.
WARNING: It is the users responsibility to ensure that the files
on the system are genuine and from a reliable source. rkhunter
can only report if a file has changed, but not on what has
caused the change. Hence, if a file has changed, and the --prop-
upd command option is used, then rkhunter will assume that the
file is genuine.
--versioncheck
This command option causes rkhunter to check if there is a later
version of the program. A command-line web browser must be
present on the system when using this option.
If this option is used via cron, then it is recommended that the
--nocolors option is also used.
An exit code of zero for this command option means that no new
version was available. An exit code of one means that an error
occurred downloading the latest version number, and a code of
two means that no error occurred but a new version is available.
--list [tests | {lang | languages} | rootkits | perl | propfiles]
This command option will list some of the supported capabilities
of the program, and then exit. The tests option lists the cur-
rently available test names (see the README file for more de-
tails about test names). The languages option lists the cur-
rently available languages, and the rootkits option lists the
rootkits that are searched for by rkhunter. The perl option
lists the installation status of the perl command and perl mod-
ules that may be used by some of the tests. Note that it is not
required to install these modules. However, if rkhunter is
forced to use perl to execute a test then the module must be
present. The propfiles option will list the file names that are
used to generate the file properties database. If no specific
option is given, then all the lists, except for the file proper-
ties database, are displayed.
-C, --config-check
This command option causes rkhunter to check its configuration
file(s), and then exit. The program will run through its normal
configuration checks as specified by the enable and disable op-
tions on the command-line and in the configuration files. That
is, only the configuration options for tests which would nor-
mally run are checked. In order to check all the configured op-
tions, then use the --enable all --disable none options on the
command line. Additionally, the program will check to see if
there are any unrecognised configuration options. If any config-
uration problems are found, then they will be displayed and the
return code will be set to 1.
It is suggested that this option is used whenever the configura-
tion file(s) have been changed.
-V, --version
This command option causes rkhunter to display its version num-
ber, and then exit.
-h, --help
This command option displays the help screen menu, and then ex-
its.
OPTIONS
rkhunter uses a configuration file, named rkhunter.conf, for many of
its configuration options. It can also use a local configuration file,
named rkhunter.conf.local, and a directory named rkhunter.d if it is
present. Both the local configuration file, and the local directory,
must be in the same directory as the main configuration file. The in-
staller does not create the local file or directory, but one, or both,
can be created by the user if required. If a directory is used, then
within the directory any file ending in .conf will be treated as a lo-
cal configuration file.
Some options can also be specified on the command-line, and these will
override the equivalent configuration file options. The configuration
file options are well documented within the main configuration file it-
self. The following are the command-line options. The defaults men-
tioned here are the program defaults, unless explicitly stated as the
configuration file default.
--appendlog
By default a new log file will be created when rkhunter runs,
and the previous log file will be renamed by having .old ap-
pended to its name. This option tells rkhunter to append to the
existing log file. If the log file does not exist, then it will
be created.
--bindir <directory>...
This option modifies which directories rkhunter looks in to find
the various commands it requires (that is, its PATH). The de-
fault is the root PATH, and an internal list of some common com-
mand directories. By default a specified directory will be ap-
pended to the default list. However, if the directory name be-
gins with the '+' character, then it will be prepended to the
list (that is, it will be put at the start of the list).
--cs2, --color-set2
By default rkhunter will display its test results in color. The
colors used are green for successful tests, red for failed tests
(warnings), and yellow for skipped tests. These colors are visi-
ble when a black background is used, but are difficult to see on
a white background. This option tells rkhunter to use a differ-
ent color set which is more suited to a white background.
--configfile <file>
The installation process will automatically tell rkhunter where
its configuration file is located. However, if necessary, this
option can be used to specify a different pathname.
If a local configuration file, or directory, is to be used, then
it must reside in the same directory as the configuration file
specified by this option.
--cronjob
This is similar to the --check command option, but it disables
several of the interactive options. When this option is used
--check, --nocolors and --skip-keypress are assumed. By default
no output is sent to stdout, so the --report-warnings-only op-
tion may be useful with this option.
--dbdir <directory>
The installation process will automatically configure where the
data files are stored for rkhunter. However, if necessary, this
option can be used to specify a different directory. The direc-
tory can be read-only, after installation, provided that neither
of the --update or --propupd options are specified, and that the
--versioncheck option is not specified if ROTATE_MIRRORS is set
to 1 in the configuration file.
--debug
This is a special option mainly for the developers. It produces
no output on stdout. Regular logging will continue as per de-
fault or as specified by the --logfile option, and the debug
output will be in a randomly generated filename which starts
with /tmp/rkhunter-debug.
--disable <test>[,<test>...]
This option tells rkhunter not to run the specified tests. Read
the README file for more information about test names. By de-
fault no tests are disabled.
--display-logfile
This option will cause the logfile to be displayed on the screen
once rkhunter has finished.
--enable <test>[,<test>...]
This option tells rkhunter to only run the specified tests. If
only one test name, other than all, is given, then the
--skip-keypress option is assumed. Read the README file for more
information about test names. By default all tests are enabled.
All the test names are listed below under TESTS.
--hash {MD5 | SHA1 | SHA224 | SHA256 | SHA384 | SHA512 |
NONE | <command>}
Both the file properties check and the --propupd command option
will use a hash function to determine a files current hash
value. This option tells rkhunter which hash function to use.
The MD5 and SHA options will look for the relevant command, and,
if not found, a perl support script will then be used to see if
a perl module supporting the function has been installed. Alter-
natively, a specific command may be specified. A value of NONE
can be used to indicate that the hash values should not be ob-
tained or used as part of the file properties check. The default
is SHA256.
Systems using prelinking must use either MD5, SHA1 or NONE.
--lang, --language <language>
This option specifies which language to use for the displayed
tests and results. The currently supported languages can be
seen by the --list command option. The default is en (English).
If a message to be displayed cannot be found in the language
file, then the English version will be used. As such, the Eng-
lish language file must always be present. The --update command
option will update the language files when new versions are
available.
-l, --logfile [file]
By default rkhunter will write out a log file. The default loca-
tion of the file is /var/log/rkhunter.log. However, this loca-
tion can be changed by using this option. If /dev/null is speci-
fied as the log file, then no log file will be written. If no
specific file is given, then the default will be used. By de-
fault rkhunter will create a new log file each time it is run.
Any previously existing logfile is moved out of the way, and has
.old appended to it.
--noappend-log
This option reverts rkhunter to its default behaviour of creat-
ing a new log file rather than appending to it.
--nocf
This option is only valid when the command-line --disable option
is used. When the --disable option is used, by default, the
configuration file option to disable tests is also used to de-
termine which tests to run. If only the --disable option is to
be used to determine which tests to run, then --nocf must be
given.
--nocolors
This option causes the result of each test to not be displayed
in a specific color. The default color, usually the reverse of
the background color, will be used (typically this is just black
and white).
--nolog
This option tells rkhunter not to write anything to a log file.
--nomow, --no-mail-on-warning
The configuration file has an option which will cause a simple
email message to be sent to a user should rkhunter detect any
warnings during system checks. This command-line option over-
rides the configuration file option, and prevents an email mes-
sage from being sent. The configuration file default is not to
email a message.
--ns, --nosummary
When the --check command option is used, by default a short sum-
mary of results is displayed at the end. This option prevents
the summary from being displayed.
--novl, --no-verbose-logging
During some tests rkhunter will log a lot of information. Use of
this option reduces the amount of logging, and so can improve
the performance of rkhunter. However, the log file will contain
less information should any warnings occur. By default verbose
logging is enabled.
--pkgmgr {RPM | DPKG | BSD | BSDng | SOLARIS | NONE}
This option is used during the file properties check or when the
--propupd command option is given. It tells rkhunter that the
current file property values should be obtained from the rele-
vant package manager. See the README file for more details of
this option. The default is NONE, which means not to use a pack-
age manager.
-q, --quiet
This option tells rkhunter not to display any output. It can be
useful when only the exit code is going to be checked. Other op-
tions may be used with this one, to force only specific items to
be displayed.
--rwo, --report-warnings-only
This option causes only warning messages to be displayed. This
can be useful when rkhunter is run via cron. Other options may
be used to force other items of information to be displayed.
--sk, --skip-keypress
When the --check command option is used, after certain sections
of tests, the user will be prompted to press the return key in
order to continue. This option disables that feature, and
rkhunter will run until all the tests have completed.
If this option has not been given, and the user is prompted to
press the return key, a single 's' character, in upper- or low-
ercase, may be given followed by the return key. rkhunter will
then continue the tests without prompting the user again (as if
this option had been given).
--summary
This option will cause the summary of test results to be dis-
played. This is the default.
--syslog [facility.priority]
When the --check command option is used, this option will cause
the start and finish times to be logged to syslog. The default
is not to log anything to syslog, but if the option is used,
then the default level is authpriv.notice.
--tmpdir <directory>
The installation process will automatically configure where tem-
porary files are to be created. However, if necessary, this op-
tion can be used to specify a different directory. The directory
must not be a symbolic link, and must be secure (root access
only).
--vl, --verbose-logging
This option tells rkhunter that when it runs some tests, it
should log as much information as possible. This can be useful
when trying to diagnose why a warning has occurred, but it obvi-
ously also takes more time. The default is to use verbose log-
ging.
-x, --autox
When this option is used, rkhunter will try and detect if the X
Window system is in use. If it is in use, then the second color
set will automatically be used (see the --color-set2 option).
This allows rkhunter to be run on, for example, a server console
(where X is not present, so the default color set should be
used), and on a users terminal (where X is in use, so the second
color set should be used). In both cases rkhunter will use the
correct color set. The configuration file default is to try and
detect X.
-X, --no-autox
This option prevents rkhunter from automatically detecting if
the X Window system is being used. See the --autox option.
TESTS
[This section to be written]
additional_rkts
This test is for SHORT_EXPLANATION. It works as part of GROUP.
Corresponding configuration file entries: ONE=one, TWO=two and
for white-listing THREE=three,three. Simple globbing
(/dev/shm/file-*) works.
all
apps
attributes
avail_modules
deleted_files
filesystem
group_accounts
group_changes
hashes
hidden_ports
hidden_procs
immutable
known_rkts
loaded_modules
local_host
malware
network
none
os_specific
other_malware
packet_cap_apps
passwd_changes
ports
possible_rkt_files
possible_rkt_strings
promisc
properties
rootkits
running_procs
scripts
shared_libs
shared_libs_path
startup_files
startup_malware
strings
suspscan
system_commands
system_configs
trojans
FILES
(For a default installation)
/etc/rkhunter.conf
/var/log/rkhunter.log
SEE ALSO
See the CHANGELOG file for recent changes.
The README file has information about installing rkhunter, as well as
specific sections on test names and using package managers.
The FAQ file should also answer some questions.
LICENSING
RootKit Hunter is licensed under the GPL, copyright Michael Boelen.
See the LICENSE file for details of GPL licensing.
CONTACT INFORMATION
This software was developed by the RootKit Hunter project team. To re-
port bugs, patches, comments and questions, please go to:
http://rkhunter.sourceforge.net/
June 2017 rkhunter(8)
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