Tag: information security

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One of the better features of Palo Alto’s PAN-OS is the ability to define dynamic block lists as firewall objects. This feature enables the firewall to poll a HTTP/HTTPS source for a list of IPs or URLs which can then be acted upon by firewall policies. There are a number of publicly available IP lists and threat intelligence feeds that can be consumed by these objects on the Palo Alto firewall but generating IP lists from internal sources, such as IDS/IPS can be cumbersome. Depending on the type of threats you encounter, it may be beneficial to block IP addresses or URLs picked up by your IDS systems. To solve this problem I wrote a python script that can be run at the command line to generate a list of IP addresses that can be consumed by Palo Alto.

Use this on a SIEM to dynamically block threats that match IDS/IPS rules. All data generated from the script is stored in a local JSON file and an IP list is outputted to a text file at the designated location. The JSON file stores current, historical and excluded IPs and the script logs information to a syslog file and to the terminal if verbose is enabled.

I wanted a relatively low maintenance solution and the initial use case for the was to temporarily block reconnaissance traffic such as port scanning. Given this, I used a penalty system to increment the time an IP is blocked each time the IP is seen. Of course, you could utilize the script to block an IP indefinitely also.

You can find the tool on Github at https://github.com/derricksmith/siem/tree/master/av2pa and the command usage is below. If you find this script useful, please drop me a comment below or on Github.



-a, –action           Define the action [add,remove,exclude,clear]

-v, –verbose        Output to terminal

-i, –ip                  IP address (required when action = add,remove,exclude)

-p, –penalty        Penalty for IP address



Add an IP address to the block list. If no penalty is defined the penalty is incremented each time the IP address is added until it reaches 16(indefinite).


Remove an IP address from the block list. Removes the IP from the current, history and exclude dictionaries.


Add an IP to the exclude list. Excluded IPs will not be processed.


Removes all IPs from the current, history and exclude dictionaries.


Cycles the blocklist and checks IPs and Penalty times. If penalty has been reached, IPs are removed from the blocklist. IPs with a penalty of 16 are not removed. Suggest running this on a cron job to periodically cycle through the IP list.


1 = 1 minute

2 = 5 minutes

3 = 10 minutes

4 = 15 minutes

5 = 30 minutes

6 = 60 minutes (1 hour)

7 = 180 minutes (3 hours)

8 = 360 minutes (6 hours)

9 = 720 minutes (12 hours)

10 = 1440 minutes (1 day)

11 = 4320 minutes (3 days)

12 = 10080 minutes (7 days)

13 = 20160 minutes (14 days)

14 = 43200 minutes (30 days)

15 = 525600 minutes (1 year)

16 = indefinite

Run at command line

Block temporarily, penalty is incremented

./av2pa.py -a add -i

Block for 1 day

./av2pa.py -a add -i -p ’10’

Block indefinately

./av2pa.py -a add -i -p ‘~’


./av2pa.py -a remove -i


./av2pa.py -a exclude -i

Run Cron

* * * * * python path/to/your/av2pa.py

Script Settings


Set location of the blocklist (e.g ‘/var/www/block_inbound.txt’). This file should be https accessible if you intend to setup a Palo Alto External Dynamic List


Set a log file location (e.g ‘/var/log/block_inbound’)


Set the local timezone(e.g ‘America/Denver’)

This post is an update to an earlier post regarding integrating Nagios with GLPI that can be found here.  Due to recent improvements in the GLPI distribution I decided to rewrite the eventhandlers.  You can find a link to GitHub at the bottom of this post.

One of the key pillars of information security is availability of resources and as a proponent of using open source solutions whenever possible I have chosen to utilize Nagios for monitoring and GLPI for helpdesk solutions.  Nagios provides powerful monitoring capabilities for equipment, hosts and services but doesn’t integrate with ticketing systems directly which can make tracking and reporting difficult.  GLPI is an ITIL based helpdesk solution that provides asset and incident/request management.  It offers generous reporting out of the box and a webservices API that can be used to extend the system.  When used together these two systems can provide a way to track host and service availability and a way to report on the health and resolution metrics of those systems over time.

As shown in my previous post regarding the integration of Nagios and GLPI, the marriage of the two systems is done using the built-in Nagios eventhandler action and the GLPI webservices API.  In previous versions of GLPI, a webservices plugin was used to create the API endpoints.  As of GLPI version 9.1, a webservices API is included in the core package.  The following procedure for integrating GLPI with Nagios will only work with GLPI 9.1+.  The event handlers have also been improved and use an object oriented approach.  The PHP xml_rpc extension has been replaced with the curl extension.  Be sure curl is installed before using these scripts.

GLPI Configuration

First, enable the API and create an API client on the API Settings page in GLPI located under Setup > General > API.   Enable both Authentication settings to allow your API client to login with credentials and an authentication key.  Be sure to copy the API URL and the API key for the client.  Although the event handler scripts can use any GLPI account that has ticket creation permission to create new tickets, it is recommended to create a new user account that will be used specifically for API transactions.

Nagios Configuration

Depending on the version of Nagios and the base operating system, Nagios could be installed into several possible locations.  I typically use Ubuntu Server and the directories listed below are for Nagios3 – your directories may be different.

First, open the host and service event handlers and change the variables at the top of each script to reflect your environment.  The scripts include the following variables:

## Required ##
$glpi_user				= '';
$glpi_password				= '';
$glpi_apikey				= '';
$glpi_host				= '';
$nagios_host				= '';
$verifypeer				= FALSE; // SETS curl_setopt ($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
$logging				= TRUE;
$critical_priority			= 5;
$warning_priority			= 3;

## Optional ##
$glpi_requester_user_id		= '';
$glpi_requester_group_id	= '';
$glpi_watcher_user_id		= '';
$glpi_watcher_group_id		= '';
$glpi_assign_user_id		= '';
$glpi_assign_group_id		= '';

The initial variables are self-explanatory.  The ssloff variable should be set to true if your site is http, you are using a self-signed certificate for https or your ssl configuration prevents successful certificate validation.  The optional variables are used to control how new tickets are opened and if initial watchers and ticket owners are used.  Use these variables to control which groups or users are notified of new tickets and when tickets are closed.

After you have modified the scripts, copy them and the glpi_api class to the Nagios eventhandler directory.  Next, modify the Nagios commands.cfg file to include the following commands.  Be sure to replace the directory with the correct event handler directory for your Nagios installation.

# 'manage-host-tickets' command definition
define command{
command_name manage-host-tickets
command_line php /usr/share/nagios3/plugins/eventhandlers/manage-host-tickets.php hoststate="$HOSTSTATE$" hoststatetype="$HOSTSTATETYPE$" eventhost="$HOSTNAME$" hostattempts="$HOSTATTEMPT$" maxhostattempts="$MAXHOSTATTEMPTS$" hostproblemid="$HOSTPROBLEMID$" lasthostproblemid="$LASTHOSTPROBLEMID$"

# 'manage-service-tickets' command definition
define command{
command_name manage-service-tickets
command_line php /usr/share/nagios3/plugins/eventhandlers/manage-service-tickets.php servicehost="$HOSTNAME$" servicestate="$SERVICESTATE$" servicestatetype="$SERVICESTATETYPE$" hoststate="$HOSTSTATE$" eventhost="$HOSTNAME$" service="$SERVICEDISPLAYNAME$" serviceattempts="$SERVICEATTEMPT$" maxserviceattempts="$MAXSERVICEATTEMPTS$" lastservicestate="$LASTSERVICESTATE$" servicecheckcommand="$SERVICECHECKCOMMAND$" serviceoutput="$SERVICEOUTPUT$" longserviceoutput="$LONGSERVICEOUTPUT$"

Next, modify your host and service templates to include the above event handler commands,

define host{
        name                            generic-host    ; The name of this host template
        notifications_enabled           1       	; Host notifications are enabled
        event_handler_enabled           1       	; Host event handler is enabled
        flap_detection_enabled          1       	; Flap detection is enabled
        failure_prediction_enabled      1       	; Failure prediction is enabled
        process_perf_data               1       	; Process performance data
        retain_status_information       1       	; Retain status information across program restarts
        retain_nonstatus_information    1       	; Retain non-status information across program restarts
		check_command                   check-host-alive
		event_handler		            manage-host-tickets
		max_check_attempts      1
		notification_interval   0
		notification_period     24x7
		notification_options    d,u,r
		contact_groups          admins
        register                        0       	; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE!
define service{
        name                            generic-service ; The 'name' of this service template
        active_checks_enabled           1       ; Active service checks are enabled
        passive_checks_enabled          1       ; Passive service checks are enabled/accepted
        parallelize_check               1       ; Active service checks should be parallelized (disabling this can lead to major performance problems)
        obsess_over_service             1       ; We should obsess over this service (if necessary)
        check_freshness                 0       ; Default is to NOT check service 'freshness'
        notifications_enabled           1       ; Service notifications are enabled
        event_handler_enabled           1       ; Service event handler is enabled
        flap_detection_enabled          1       ; Flap detection is enabled
        failure_prediction_enabled      1       ; Failure prediction is enabled
        process_perf_data               1       ; Process performance data
        retain_status_information       1       ; Retain status information across program restarts
        retain_nonstatus_information    1       ; Retain non-status information across program restarts
		notification_interval           0		; Only send notifications on status change by default.
		event_handler		            manage-service-tickets
		is_volatile                     0
		check_period                    24x7
		normal_check_interval           5
		retry_check_interval            1
		max_check_attempts              4
		notification_period             24x7
		notification_options            w,u,c,r
		contact_groups                  admins
        register                        0       ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL SERVICE, JUST A TEMPLATE!

After you are finished be sure to restart the Nagios service.  You will now receive helpdesk tickets in GLPI when alerts are created in Nagios and those tickets will be removed when the service or host has been restored.  GLPI will handle the appropriate  notifications.

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