[id='sec-Using-AIDE']
= Checking Integrity With *AIDE*
:experimental:
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Advanced Intrusion Detection Environment (AIDE) is a utility that creates a database of files on the system, and then uses that database to ensure file integrity and detect system intrusions.

== Installing *AIDE*

. To install the _aide_ package:
+
[source,shell,subs="attributes"]
----
$ sudo dnf install aide
----
. To generate an initial database:
+
[source,shell,subs="attributes"]
----
$ sudo aide --init
Start timestamp: 2018-07-11 12:35:47 +0200 (AIDE 0.16)
AIDE initialized database at /var/lib/aide/aide.db.new.gz

Number of entries:	150666

---------------------------------------------------
The attributes of the (uncompressed) database(s):
---------------------------------------------------

/var/lib/aide/aide.db.new.gz
  MD5      : 0isjEPsCORFk7laoGGz8tQ==
  SHA1     : j0aPLakWChM+TAuxfVIpy9nqBOE=
  RMD160   : nYyyx0AGZj4e5rwcz77afasXFrw=
  TIGER    : IBVo5A2A4En1kM6zDjD/MnlkN4QWeSOw
  SHA256   : YveypaI9c5PJNvPSZf8YFfjCMWfGUA8q
             vyqLpLJWY0E=
  SHA512   : TiUYmHYflS3A+j17qw5mW78Fn2yXLpCF
             1LE1/RhiqqtMn1MjkKDrr+3TE+/vWfa4
             7253cDhNmC6hoFndkS67Xw==


End timestamp: 2018-07-11 12:37:35 +0200 (run time: 1m 48s)
----
+
NOTE: In the default configuration, the *aide --init* command checks just a set of directories and files defined in the `/etc/aide.conf` file. To include additional directories or files in the AIDE database, and to change their watched parameters, edit `/etc/aide.conf` accordingly.

. To start using the database, remove the `.new` substring from the initial database file name:
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[source,shell,subs="attributes"]
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$ sudo mv /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz
----

. To change the location of the *AIDE* database, edit the `/etc/aide.conf` file and modify the `DBDIR` value. For additional security, store the database, configuration, and the `/usr/sbin/aide` binary file in a secure location such as a read-only media.
+
IMPORTANT: To avoid SELinux denials after the AIDE database location change, update your SELinux policy accordingly. See the link:https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/SELinux_Users_and_Administrators_Guide/[SELinux User's and Administrator's Guide] for more information.

== Performing Integrity Checks

To initiate a manual check:

[source,shell,subs="attributes"]
----
$ sudo aide --check
Start timestamp: 2018-07-11 12:41:20 +0200 (AIDE 0.16)
AIDE found differences between database and filesystem!!

Summary:
  Total number of entries:	150667
  Added entries:		1
  Removed entries:		0
  Changed entries:		2

---------------------------------------------------
Added entries:
---------------------------------------------------

f++++++++++++++++: /etc/cups/subscriptions.conf.O
...
[output truncated]
----

At a minimum, *AIDE* should be configured to run a weekly scan. At most, *AIDE* should be run daily. For example, to schedule a daily execution of AIDE at _04:05_ a.m. using the *cron* command, see the xref:f{MAJOROSVER}@fedora:system-administrators-guide:monitoring-and-automation/Automating_System_Tasks.adoc[Automating System Tasks] chapter in the System Administrator's Guide.

Add the following line to the `/etc/crontab` file:

[source,shell,subs="attributes"]
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 05 4 * * * root /usr/sbin/aide --check
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== Updating an *AIDE* Database

After verifying the changes of your system such as, package updates or configuration files adjustments, update your baseline *AIDE* database:

[source,shell,subs="attributes"]
----
$ sudo aide --update
----
The *aide --update* command creates the `/var/lib/aide/aide.db.new.gz` database file. To start using it for integrity checks, remove the `.new` substring from the file name.

== Additional Resources

For additional information on *AIDE*, see the following documentation:

 - link:https://static.open-scap.org/ssg-guides/ssg-sl7-guide-ospp-rhel7-server.html#xccdf_org.ssgproject.content_group_aide[Guide to the Secure Configuration of Red Hat Enterprise Linux 7 (OpenSCAP Security Guide): Verify Integrity with AIDE]

 - link:http://aide.sourceforge.net/stable/manual.html[The AIDE manual]