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OSSEC is an Open Source Host-based Intrusion Detection System that performs log analysis, file integrity checking, policy monitoring, rootkit detection, real-time alerting and active response. It runs on most operating systems, including Linux, MacOS, Solaris, HP-UX, AIX and Windows. It also includes agentless monitoring for use with for example Cisco, HP or Juniper hardware.

This tutorial covers the installation of the OSSEC server, the standard OSSEC Web UI and the Analogi dashboard on Ubuntu 12.04. It also covers OSSEC setup with MySQL support, including a Makefile bugfix. Last but not least it shows you how to install the OSSEC agent on a *NIX system.

There is a new version of OSSEC, 2.8. There is also a new version of this tutorial, for the new OSSEC and for Ubuntu 14.04. Click here to read it.

This tutorial is written for an ubuntu 12.04 OSSEC server, but can be easily adapted to other *NIX operating systems. It only covers basic OSSEC client/server configuration, not automatic blocking or comprehensive configuration settings. It gets you started, the rest is available in the documentation: http://www.ossec.net/doc/

Steps

• Installing development packages
• Installing Apache, PHP and MySQL
• Configuring MySQL
• Compiling the OSSEC server
  • Makefile fix for Ubuntu
• Basic OSSEC setup with MySQL
• Installing OSSEC Web UI

• Installing Analogi Web Dashboard

• Installing and configuring a client

Requirements

• An Ubuntu 12.04 server
• Apache2, PHP, MySQL and development packages
• OSSEC clients to monitor (*NIX or Windows machines, Cisco switches etc).

Installing development packages

OSSEC is installed from source, therefore you need development packages. This is both for the OSSEC clients as for the OSSEC server:

apt-get install build-essential make libssl-dev

Installing Apache, MySQL and PHP

This is fairly simple on Ubuntu. It is all covered with apt:

apt-get install mysql-server libmysqlclient-dev mysql-client apache2 php5 libapache2-mod-php5 php5-mysql php5-curl php5-gd php5-intl php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-ming php5-ps php5-pspell php5-recode php5-snmp php5-sqlite php5-tidy php5-xmlrpc php5-xsl

Remember to give a strong root password for MySQL. Next finish MySQL with a secure installation:

mysql_secure_installation

Accept all the suggested options. Now restart all requires services:

/etc/init.d/apache2 restart
/etc/init.d/mysqld restart

Compiling the OSSEC server

Download and verify OSSEC, either via wget or from the website: http://www.ossec.net/?page_id=19

wget http://www.ossec.net/files/ossec-hids-2.7.tar.gz

md5sum ossec-hids-2.7.tar.gz
ossec-hids-2.7.tar.gz: 71cd21a20f22b8eafffa3b57250f0a70

From the OSSEC website:

MD5(ossec-hids-2.7.tar.gz)= 71cd21a20f22b8eafffa3b57250f0a70
SHA1(ossec-hids-2.7.tar.gz)= 721aa7649d5c1e37007b95a89e685af41a39da43

If it is correct, then extract it:

tar -xf ossec-hids-2.7.tar.gz
cd ossec-hids-2.7

We first need to fix MySQL support in the installation. Read on:

Makefile fix for Ubuntu

Because of some Ubuntu specific errors in compiling with MySQL support we need to edit the MySQL Makefile:

cd src
vim os_dbd/Makefile

Change this line:

${CC} ${CFLAGS} ${OS_LINK} ${DBFLAGS} ${CDB} ${LOCAL} ${OBJS} -o ${NAME}

To this:

 ${CC} ${CFLAGS} ${OS_LINK} ${DBFLAGS} ${LOCAL} ${OBJS} -o ${NAME} ${CDB}

This is only needed in Ubuntu, Debian works fine.

Run:

make setdb
Error: PostgreSQL client libraries not installed.
Info: Compiled with MySQL support.

Continue with the compilation/installation:

cd ../
./install.sh

  ** For installation in English, choose [en].
 OSSEC HIDS v2.7 Installation Script - http://www.ossec.net

 You are about to start the installation process of the OSSEC HIDS.
 You must have a C compiler pre-installed in your system.
 If you have any questions or comments, please send an e-mail
 to dcid@ossec.net (or daniel.cid@gmail.com).

  - System: Linux vps1.sparklingclouds.nl 3.2.0-042stab076.8
  - User: root
  - Host: vps1.sparklingclouds.nl
  -- Press ENTER to continue or Ctrl-C to abort. --
1- What kind of installation do you want (server, agent, local, hybrid or help)? server
  - Server installation chosen.

2- Setting up the installation environment.
 - Choose where to install the OSSEC HIDS [/var/ossec]:
    - Installation will be made at  /var/ossec .

3- Configuring the OSSEC HIDS.
  3.1- Do you want e-mail notification? (y/n) [y]:
   - What's your e-mail address? ossec@example.org
   - We found your SMTP server as: mail.raymii.org.
   - Do you want to use it? (y/n) [y]: y
   --- Using SMTP server:  mail.raymii.org.

  3.2- Do you want to run the integrity check daemon? (y/n) [y]:
   - Running syscheck (integrity check daemon).

  3.3- Do you want to run the rootkit detection engine? (y/n) [y]:
   - Running rootcheck (rootkit detection).

  3.4- Active response allows you to execute a specific
       command based on the events received. For example,
       you can block an IP address or disable access for
       a specific user.
       More information at:
       http://www.ossec.net/en/manual.html#active-response

   - Do you want to enable active response? (y/n) [y]:
     - Active response enabled.

   - By default, we can enable the host-deny and the
     firewall-drop responses. The first one will add
     a host to the /etc/hosts.deny and the second one
     will block the host on iptables (if linux) or on
     ipfilter (if Solaris, FreeBSD or NetBSD).
   - They can be used to stop SSHD brute force scans,
     portscans and some other forms of attacks. You can
     also add them to block on snort events, for example.

   - Do you want to enable the firewall-drop response? (y/n) [y]:
     - firewall-drop enabled (local) for levels >= 6

   - Default white list for the active response:
      - 205.185.112.68
      - 205.185.112.69
   - Do you want to add more IPs to the white list? (y/n)? [n]:

  3.5- Do you want to enable remote syslog (port 514 udp)? (y/n) [y]:
   - Remote syslog enabled.

  3.6- Setting the configuration to analyze the following logs:
    -- /var/log/messages
    -- /var/log/auth.log
    -- /var/log/syslog
    -- /var/log/mail.info
    -- /var/log/dpkg.log

 - If you want to monitor any other file, just change
   the ossec.conf and add a new localfile entry.
   Any questions about the configuration can be answered
   by visiting us online at http://www.ossec.net .
   --- Press ENTER to continue ---

5- Installing the system
 - Running the Makefile
INFO: Little endian set.

 *** Making zlib (by Jean-loup Gailly and Mark Adler)  ***
[...]
 *** Making os_xml ***
[...]
 *** Making os_regex ***
[...]
 *** Making os_net ***
[...]
 *** Making shared ***
[...]
 *** Making config ***
[...]
 *** Making os_maild ***
[...]
 *** Making os_dbd ***
[...]
 *** Making os_csyslogd ***
[...]
 *** Making agentlessd ***
[...]
 *** Making os_execd ***
[...]
 *** Making analysisd ***
[...]
 *** Making logcollector ***
[...]
 *** Making remoted ***
[...]
 *** Making client-agent ***
[...]
 *** Making addagent ***
[...]
 *** Making util ***
[...]
 *** Making rootcheck ***
[...]
 *** Making syscheckd ***
[...]
 *** Making monitord ***
[...]
 *** Making os_auth ***
[...]

 - System is Debian (Ubuntu or derivative).
 - Init script modified to start OSSEC HIDS during boot.
 - Configuration finished properly.
 - To start OSSEC HIDS:
                /var/ossec/bin/ossec-control start

 - To stop OSSEC HIDS:
                /var/ossec/bin/ossec-control stop

 - The configuration can be viewed or modified at /var/ossec/etc/ossec.conf
    Thanks for using the OSSEC HIDS.
    If you have any question, suggestion or if you find any bug,
    contact us at contact@ossec.net or using our public maillist at
    ossec-list@ossec.net
    ( http://www.ossec.net/main/support/ ).
    More information can be found at http://www.ossec.net
    ---  Press ENTER to finish (maybe more information below). ---

 - In order to connect agent and server, you need to add each agent to the server.
   Run the 'manage_agents' to add or remove them:

   /var/ossec/bin/manage_agents

   More information at:
   http://www.ossec.net/en/manual.html#ma

OSSEC is now installed. Restart it:

/var/ossec/bin/ossec-control restart

Continue to the next step for MySQL setup.

Configuring MySQL

We need to create a user and database for OSSEC. Go to a MySQL shell:

mysql -u root -p
Enter password:
[...]

mysql> create database ossec;
Query OK, 1 row affected (0.02 sec)

grant INSERT,SELECT,UPDATE,CREATE,DELETE,EXECUTE on ossec.* to ossec_u;
Query OK, 0 rows affected (0.00 sec)

set password for ossec_u = PASSWORD('Passw0rd');
Query OK, 1 row affected (0.01 sec)

flush privileges;
Query OK, 0 rows affected (0.00 sec)

quit;

The database also needs a schema. OSSEC provides a schema, it is located in the extracted OSSEC folder, src/os_dbd. Import it into MySQL:

mysql -u root -p ossec < src/os_dbd/mysql.schema

That's it for the database setup. Continue to see the OSSEC configuration.

OSSEC MySQL configuration

We have to add the database config to /var/ossec/etc/ossec.conf:

<ossec_config>
    <database_output>
        <hostname>127.0.0.1</hostname>
        <username>ossec_u</username>
        <password>Passw0rd</password>
        <database>ossec</database>
        <type>mysql</type>
    </database_output>
</ossec_config>

Save it, then enable the database in OSSEC:

/var/ossec/bin/ossec-control enable database
/var/ossec/bin/ossec-control restart 

Installing OSSEC Web UI

This is also quite simple. Because we've already set up Apache and PHP, we can just download the web UI and extract to /var/www/:

wget http://www.ossec.net/files/ossec-wui-0.8-beta-1.tar.gz
tar -xf ossec-wui-0.8-beta-1.tar.gz
mkdir /var/www/ossec/
mv ossec-wui-0.8-beta-1/* /var/www/ossec/
chown www-data:www-data /var/www/ossec/tmp/
chmod 666 /var/www/ossec/tmp

We use the web UI Beta because there are a lot of errors (like broken search) in the stable 0.3 version. We also set the correct permissions on the tmp/ folder. Afterwards the web ui is visible at http://hostname/ossec/.

Installing Analogi Web Dashboard

The Analogi dashboard is a nice and informative dashboard around OSSEC, which provides more visual information then the standard Web UI. The standard Web UI has better search functions, the Dashboard can be used for example on a Wall Mounted monitor and such.

Installation consists out of cloning the git repo and entering the settings file:

cd /var/www
git clone https://github.com/ECSC/analogi.git
cp analogi/db_ossec.php.new analogi/db_ossec.php
vim analogi/db_ossec.php        

Edit the relevant settings for the MySQL database configuration. When correctly configured the Analogi webinterface can be found at http://hostname/analogi/.

The OSSEC server is now correctly set up.

Client installation

Download and verify the OSSEC stable .tar.gz file as described above. This time, do an agent installation. See the output below:

root@testclient:~/ossec-hids-2.7# ./install.sh

  ** Para instalao em portugus, escolha [br].
  ** ,  [cn].
  ** Fur eine deutsche Installation wohlen Sie [de].
  **    ,  [el].
  ** For installation in English, choose [en].
  ** Para instalar en Espaol , eliga [es].
  ** Pour une installation en franais, choisissez [fr]
  ** A Magyar nyelv teleptshez vlassza [hu].
  ** Per l'installazione in Italiano, scegli [it].
  ** [jp].
  ** Voor installatie in het Nederlands, kies [nl].
  ** Aby instalowa w jzyku Polskim, wybierz [pl].
  **       , [ru].
  ** Za instalaciju na srpskom, izaberi [sr].
  ** Trke kurulum iin sein [tr].
  (en/br/cn/de/el/es/fr/hu/it/jp/nl/pl/ru/sr/tr) [en]:
 OSSEC HIDS v2.7 Installation Script - http://www.ossec.net

 You are about to start the installation process of the OSSEC HIDS.
 You must have a C compiler pre-installed in your system.
 If you have any questions or comments, please send an e-mail
 to dcid@ossec.net (or daniel.cid@gmail.com).

  - System: Linux testclient.raymii.nl 3.8.0-21-generic-pae
  - User: root
  - Host: testclient.raymii.nl

  -- Press ENTER to continue or Ctrl-C to abort. --

1- What kind of installation do you want (server, agent, local, hybrid or help)? agent
  - Agent(client) installation chosen.

2- Setting up the installation environment.
 - Choose where to install the OSSEC HIDS [/var/ossec]:
    - Installation will be made at  /var/ossec .

3- Configuring the OSSEC HIDS.
./install.sh: 372: ./install.sh: [[: not found

  3.2- Do you want to run the integrity check daemon? (y/n) [y]: y
   - Running syscheck (integrity check daemon).

  3.3- Do you want to run the rootkit detection engine? (y/n) [y]:
   - Running rootcheck (rootkit detection).

  3.4 - Do you want to enable active response? (y/n) [y]:

  3.5- Setting the configuration to analyze the following logs:
    -- /var/log/auth.log
    -- /var/log/syslog
    -- /var/log/dpkg.log

 - If you want to monitor any other file, just change
   the ossec.conf and add a new localfile entry.
   Any questions about the configuration can be answered
   by visiting us online at http://www.ossec.net .

   --- Press ENTER to continue ---

5- Installing the system
 - Running the Makefile
INFO: Little endian set.

Client OSSEC config

Adding a client to OSSEC is quite simple. First you add the client to the server, which gives you a key. Then you add this key to the client, edit the config file on the client and that's it.

First we need to generate a key on the OSSEC server for this client. We do this by running/var/ossec/bin/manage_agents, option A, then entering the hostname, IP and ID for the client we want to add. Do these steps on the OSSEC server!:

root@ossec:~# /var/ossec/bin/manage_agents

****************************************
* OSSEC HIDS v2.7 Agent manager.     *
* The following options are available: *
****************************************
   (A)dd an agent (A).
   (E)xtract key for an agent (E).
   (L)ist already added agents (L).
   (R)emove an agent (R).
   (Q)uit.
Choose your action: A,E,L,R or Q: a

- Adding a new agent (use '\q' to return to the main menu).
  Please provide the following:
   * A name for the new agent: testclient
   * The IP Address of the new agent: 10.0.51.32
   * An ID for the new agent[001]:
Agent information:
   ID:001
   Name:testclient
   IP Address:10.0.51.32

Confirm adding it?(y/n): y
Agent added.

Now we find out the key for the OSSEC client:

root@ossec:~# /var/ossec/bin/manage_agents

****************************************
* OSSEC HIDS v2.7 Agent manager.     *
* The following options are available: *
****************************************
   (A)dd an agent (A).
   (E)xtract key for an agent (E).
   (L)ist already added agents (L).
   (R)emove an agent (R).
   (Q)uit.
Choose your action: A,E,L,R or Q: e

Available agents:
   ID: 001, Name: testclient, IP: 10.0.51.32
Provide the ID of the agent to extract the key (or '\q' to quit): 001

Agent key information for '001' is:
SD[...]AAUjd=

** Press ENTER to return to the main menu.

Then switch to the OSSEC client and execute the manage_agents:

root@ossec:~# /var/ossec/bin/manage_agents

****************************************
* OSSEC HIDS v2.7 Agent manager.     *
* The following options are available: *
****************************************
   (I)mport key from the server (I).
   (Q)uit.
Choose your action: I or Q: i

* Provide the Key generated by the server.
* The best approach is to cut and paste it.
*** OBS: Do not include spaces or new lines.

Paste it here (or '\q' to quit): SD[...]AAUjd=

Agent information:
   ID:001
   Name:testclient
   IP Address:10.0.51.32

Confirm adding it?(y/n): y
Added.
** Press ENTER to return to the main menu.

And then this needs to be in the /var/ossec/etc/ossec.conf file:

<client>
  <server-hostname>ossec.raymii.nl</server-hostname>
</client>

Where ossec.raymii.nl is your OSSEC server URL or IP.

Now restart the OSSEC agents:

/var/ossec/bin/ossec-control restart
Killing ossec-monitord ..
Killing ossec-logcollector ..
Killing ossec-remoted ..
Killing ossec-syscheckd ..
Killing ossec-analysisd ..
Killing ossec-maild ..
Killing ossec-execd ..
Killing ossec-dbd ..
ossec-agentlessd not running ..
OSSEC HIDS v2.7 Stopped
Starting OSSEC HIDS v2.7 (by Trend Micro Inc.)...
Started ossec-dbd...
Started ossec-agentlessd...
Started ossec-maild...
Started ossec-execd...
Started ossec-analysisd...
Started ossec-logcollector...
Started ossec-remoted...
Started ossec-syscheckd...
Started ossec-monitord...
Completed.

That's it. Repeat these steps for any client that needs to be added. There are both puppetfiles and chef cookbooks to manage this process.

Bonus Tips

Here are a few bonus tips/config examples for OSSEC:

Ignoring rules

To very simply ignore rules based on rule id, add them to the XML file located in/var/ossec/rules/local_rules/xml, either on the ossec client for one machine or the ossec server to ignore on all machines:

<!-- Specify here a list of rules to ignore. -->
<!-- 3334 postfix start  -->
<!-- 3333 postfix stop -->
<rule id="100030" level="0">
    <if_sid>3333, 3334</if_sid>
    <description>List of rules to be ignored.</description>
</rule>

Monitoring additional log files

The OSSEC agent by default only monitors a few log files. To add more, edit the/var/ossec/etc/ossec.conf file and add a line like this:

<localfile>
    <location>/var/log/*</location>
    <log_format>syslog</log_format>
</localfile>

This will add all files under /var/log. This might be a lot, you can also just add multiple<localfile> blocks with filenames.

Firewall

You need to allow UDP port 1514 between OSSEC server and clients. Otherwise you get errors like this:

2013/09/06 19:53:00 ossec-agentd: INFO: Using IPv4 for: 10.0.51.31 .
2013/09/06 19:53:21 ossec-agentd(4101): WARN: Waiting for server reply (not started). Tried: 'ossec.raymii.nl/10.0.51.31'.

Removing OSSEC

If you want to remove OSSEC, either the client or the server, read this tutorial. It covers all the steps required to uninstall OSSEC

출처 : raymii.org