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Tutorial AlertClientExecuter

sqall01 edited this page Oct 26, 2018 · 10 revisions

Tutorial - AlertR Alert Client Executer

In this document a tutorial for the version 0.501 is given.

Table of Contents

Tutorial

Tutorial

This tutorial describes the basic configuration of the AlertR Alert Client Executer. It can be used as foundation to develop an own AlertR system setup. This tutorial assumes you have set up the AlertR Server according to the provided Server Tutorial.

The client is described as the following by the installation:

sqall@towel:~$ python alertRinstaller.py -l

[...]
AlertR Alert Client Executer
----------------------------
Instance:
alertClientExecuter

Type:
alert

Version:
0.400-1

Dependencies:
None

Description:
This client handles triggered alerts and is written to execute a configured script or command with arguments. The arguments are configured and the command is executed on a triggered sensor alert event or when all alerts are stopped. For example you can start a init script on a Linux system when a sensor alert was triggered and when all alerts are stopped the init script is stopped.
[...]

Installation

The AlertR Alert Client Executer does not have special prerequisites. Therefore, we can install it directly.

It is always a good idea to have an own user for a daemon. Therefore, we create a user that runs the AlertR Alert Client Executer called alertr:

root@towel:/home/sqall# adduser --disabled-password alertr
Adding user `alertr' ...
Adding new group `alertr' (1002) ...
Adding new user `alertr' (1002) with group `alertr' ...
Creating home directory `/home/alertr' ...
Copying files from `/etc/skel' ...
Changing the user information for alertr
Enter the new value, or press ENTER for the default
    Full Name []:
    Room Number []:
    Work Phone []:
    Home Phone []:
    Other []:
Is the information correct? [Y/n] y

To switch into this user in the terminal you can use the following command:

root@towel:/home/sqall# su alertr

Please note that this is only possible as root user. If you are trying this command as another user you will get a password prompt for the user alertr, which does not have a password.

Afterwards, you can use the installation script provided by AlertR to install the client.

alertr@towel:~$ wget https://raw.githubusercontent.com/sqall01/alertR/master/alertRinstaller.py

alertr@towel:~$ mkdir alertClientExecuter

alertr@towel:~$ python alertRinstaller.py -i alertClientExecuter -t ./alertClientExecuter/

Configuration

The following describes the configuration of the AlertR Alert Client Executer. It shows a basic configuration that can be used as a template for own installations.

Certificate

For security reasons, the AlertR system enforces a TLS connection. During the installation of the AlertR server, you created a certificate file with the name alertr_server.crt. This file is needed by the client in order to verify the connection. Please copy it to the host you are installing this client on. This tutorial assumes that you have stored the certificate file in the following location: /home/alertr/alertClientExecuter/config/alertr_server.crt.

User Credentials

The client has to authenticate itself before it can work with the server. Therefore, we need to set up user credentials on the AlertR server for this client. We execute the following command with the manageUsers.py script of the server which is located in the installation directory of the server (see Users Management for further information):

alertr@towel:/home/alertr/server# python manageUsers.py -a -u user_alert_exec -p password_alert_exec -t alert -i alertClientExecuter

Please make sure that the AlertR Server is not running while adding a user.
Otherwise it can lead to an inconsistent state and a corrupted database.
Are you sure to continue?
(y/n): y

AlertLevels

This tutorial assumes the alert levels configured in the AlertR Server tutorial. The client will use the following for its configuration:

AlertLevel Name Functionality
1 Silent Notification Used to silently notify the user.
2 Urgent Notification Used to "loudly" notify the user.

AlertLevel 1 is used for sensors that trigger a sensorAlert, but not an urgent one. This alertLevel triggers always despite if the alarm system is activated or not.

AlertLevel 2 is used for sensors that trigger urgent sensorAlerts, such as a break in attempt. These sensors should notify the user immediately and loudly at best.

Configuration File

Every AlertR installation has a template configuration file with detailed comments that describe the functionality of each option. To use it as a draft, you can just copy the template file and modify your new configuration file.

alertr@towel:~/alertClientExecuter/config$ cp config.xml.template config.xml

The configuration file itself is split into the following parts:

  • General
  • SMTP
  • Update
  • Alerts

In this tutorial, we are going through each of these parts separately and describe why we configured it like that.

General

The general section is used for options such as certificate file location. In our tutorial configuration, the section looks like this:

	<general>

		<log
			file="/home/alertr/alertClientExecuter/config/logfile.log"
			level="INFO" />

		<server
			host="localhost"
			port="44556"
			caFile="/home/alertr/alertClientExecuter/config/alertr_server.crt" />

		<client
			certificateRequired="False"
			certFile="/absolute/path/to/client.crt"
			keyFile="/absolute/path/to/client.key" />

		<credentials
			username="user_alert_exec"
			password="password_alert_exec" />

		<connection
			persistent="True" />

	</general>

Section log is used to configure the log file setup. The file attribute sets the location for the log file. Please note that this has to be the absolute path to the location. Make sure it exists and is writable by the user that starts the AlertR client. Otherwise the client will not start. For example, the directory /var/log is usually only writable by the "root" user and users of the group "syslog". If you want the client log file in this directory, please create a sub-directory for the AlertR client log file and set the correct permissions on it. The level attribute sets the log level. Possible values are DEBUG, INFO, WARNING, ERROR, CRITICAL.

Section server is used to configure the server connection setup. The host and port attribute sets the address and port of the AlertR server. The port was previously configured in the server configuration file. The address can either be a name that can be resolved by the DNS system or an IP address. The caFile attribute sets the location of the certificate file that is used to authenticate the server (see Certificate). Please make sure that the location is an absolute path to the file.

Section client is used to configure the client connection setup. The certificateRequired attribute determines if the client needs a certificate to connect to the server or not. The certFile and keyFile are used to determine the client certificate and key file. Since this tutorial is not using client certificates, we do not have to set sane values here.

Section credentials is used to configure the login credentials of this client. The credentials were configured in a previous step of this Tutorial and must be the same as in this configuration file.

Section connection is used to configure the connection to the server. The persistent attribute is used to configure if the connection to the server has to be persistent. This means that if the client disconnects, a sensorAlert is created by the server.

SMTP

The smtp section is used for options that configure the used SMTP server. In our tutorial configuration, the section looks like this:

	<smtp>

		<general
			activated="True"
			fromAddr="alertClientExecuter@alertr.de"
			toAddr="myalarmaddress@example.org" />

		<server
			host="127.0.0.1"
			port="25" />

	</smtp>

Section general is used to configure the basic options of the eMail notification. The eMail notification is used if problems on the AlertR client occur that can not be solved (like connection problems). The activated attribute determines if the eMail notification is activated or not. If it is deactivated, the rest of the options in the whole smtp section are ignored. The fromAddr attribute sets the used eMail address from which the eMail notification is sent. The toAddr attribute determines the eMail address the notification is sent to.

Section server is used to configure the SMTP server that is used to send the eMail notification. The host attribute sets the address and the port attribute sets the port of the used SMTP server. At the moment, only "127.0.0.1" is allowed as address and port 25. This means you have to set up a local SMTP server in order to send eMail notifications. Personally, I would suggest to set up a local Postfix SMTP server that can forward eMails like in this Tutorial. Please note that the local SMTP server has to accept eMails from localhost without any authentication since it is not supported by AlertR yet.

Update

The update section is used to give the online repository for updates. In our tutorial configuration, the section looks like this:

	<update>

		<server
			host="raw.githubusercontent.com"
			port="443"
			location="/sqall01/alertR/master/"
			caFile="/etc/ssl/certs/DigiCert_High_Assurance_EV_Root_CA.pem" />

	</update>

Section server is used to configure the remote update repository. Normally, the default configuration can be used here (which is this repository). The host attribute gives the remote server location of the repository. The port attribute gives the port on which the repository is reachable (AlertR uses HTTPS for it). The location attribute sets the location on the remote repository. The caFile attribute gives the local location of the certificate that is used to verify the HTTPS connection. The default value is the location on Debain/Ubuntu distributions of the current certificate that is used by Github.

Alerts

The alerts section configures the alerts of this client. In our tutorial configuration, the section looks like this:

	<alerts>

		<alert>

			<general
				id="0"
				description="Do Some Notification" />

			<alertLevel>1</alertLevel>
			<alertLevel>2</alertLevel>

			<executer
				execute="/usr/bin/python">

				<triggerArgument>/home/alertr/alertClientExecuter/scripts/notify.py</triggerArgument>
				<triggerArgument>start</triggerArgument>

				<stopArgument>/home/alertr/alertClientExecuter/scripts/notify.py</stopArgument>
				<stopArgument>stop</stopArgument>

			</executer>

		</alert>

		<alert>

			<general
				id="1"
				description="Do Important Stuff" />

			<alertLevel>2</alertLevel>

			<executer
				execute="/bin/bash">

				<triggerArgument>/home/alertr/alertClientExecuter/scripts/important.sh</triggerArgument>
				<triggerArgument>start</triggerArgument>

				<stopArgument>/home/alertr/alertClientExecuter/scripts/important.sh</stopArgument>
				<stopArgument>stop</stopArgument>

			</executer>

		</alert>

	</alerts>

Each configured alert is set up in its own <alert>...</alert> context. The context has three main sections: general, alertLevel and executer. The following describes the settings of each section.

Section general is used to configure the basic alert settings. The id attribute gives the local id of the configured alert. This id has to be unique for each alert of this client. Since we configure two alerts, we give them the id 0 and 1. The description attribute gives a short description of the alert.

The alertLevel sections set the alertLevel the alerts are triggered by. In our tutorial, both alerts trigger by alertLevel 2 and the first alert triggers also by alertLevel 1.

Section executer configures the executer alert settings. The execute attribute sets the program that should be executed by a received sensorAlert. Normally, a script can be used directly in here. However, we encountered sometimes problems with this (even when a shebang was set and the script file was executable). To prevent this problem, we use the script interpreter as a program that should be executed and the script itself is used as first argument. The triggerArgument attribute sets one argument used for the program when a sensorAlert is triggered and the alert is executed. As first argument, we use the script file in both alerts. As second argument, we use the argument "start". The stopArgument attribute sets one argument used for the program when all alerts should be stopped. As first argument, we use again the script file in both alerts. As second argument, we use the argument "stop".

Autostart

If you want the AlertR client to start automatically after a reboot of the host, you have to set it up. In this tutorial, I will give two examples on how to set up the autostart of the AlertR client depending on your system using systemd or just init.d.

Init.d

An init.d script is provided by the AlertR installation. The only thing you have to do is to copy and configure it correctly. The following command copies it to the correct location, sets the permissions correctly and installs it:

root@towel:/home/alertr/alertClientExecuter/init.d_example# cp alertRalertExecuter.sh /etc/init.d/

root@towel:/etc/init.d# chown root:root alertRalertExecuter.sh
root@towel:/etc/init.d# chmod 755 alertRalertExecuter.sh

root@towel:/etc/init.d# update-rc.d alertRalertExecuter.sh defaults
 Adding system startup for /etc/init.d/alertRalertExecuter.sh ...
   /etc/rc0.d/K20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc1.d/K20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc6.d/K20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc2.d/S20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc3.d/S20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc4.d/S20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh
   /etc/rc5.d/S20alertRalertExecuter.sh -> ../init.d/alertRalertExecuter.sh

Next we have to configure the init.d script correctly. The following changes have to be made to the script:

[...]
# change USER to the user which runs the alertRclient
USER=alertr
# change DAEMON to the path to run the alertRclient
DAEMON=/home/alertr/alertClientExecuter/alertRclient.py
[...]

In order to work correctly, the AlertR client has to be executable. With the following, we change the permissions of the AlertR client:

alertr@towel:~/alertClientExecuter$ chmod 755 alertRclient.py

To start the client as daemon, we can now execute:

root@towel:/home/alertr/alertClientExecuter# /etc/init.d/alertRalertExecuter.sh start

The log file of the client (it is created in the directory you have configured in the General Section) should now show the following:

[...]
08/20/2016 14:28:46 INFO: [alertRclient.py] Connecting to server.
08/20/2016 14:28:46 INFO: [alertRclient.py] Starting watchdog thread.
08/20/2016 14:28:46 INFO: [alertRclient.py] Initializing alerts.
08/20/2016 14:28:46 INFO: [alertRclient.py] Starting update check thread.
08/20/2016 14:28:46 INFO: [alertRclient.py] Client started.

Systemd

If your system uses systemd for its autostart, you have to configure the AlertR client a bit different. Copying the template and setting permissions is still the same:

root@towel:/home/alertr/alertClientExecuter/init.d_example# cp alertRalertExecuter.sh /etc/init.d/

root@towel:/etc/init.d# chown root:root alertRalertExecuter.sh
root@towel:/etc/init.d# chmod 755 alertRalertExecuter.sh

Configuring the init.d script correctly is also the same:

[...]
# change USER to the user which runs the alertRclient
USER=alertr
# change DAEMON to the path to run the alertRclient
DAEMON=/home/alertr/alertClientExecuter/alertRclient.py
[...]

Now, systemd has to be configured. For this we copy the template service file to the correct location and install the service:

root@towel:/home/alertr/alertClientExecuter/init.d_example# cp alertRalertExecuter.service /etc/systemd/system/

root@towel:/home/alertr/alertClientExecuter# systemctl enable alertRalertExecuter.service

The AlertR client can be started with the following command:

root@towel:/home/alertr/alertClientExecuter# service alertRalertExecuter.sh status

The log file of the client (it is created in the directory you have configured in the General Section) should now show the following:

[...]
08/20/2016 14:28:46 INFO: [alertRclient.py] Connecting to server.
08/20/2016 14:28:46 INFO: [alertRclient.py] Starting watchdog thread.
08/20/2016 14:28:46 INFO: [alertRclient.py] Initializing alerts.
08/20/2016 14:28:46 INFO: [alertRclient.py] Starting update check thread.
08/20/2016 14:28:46 INFO: [alertRclient.py] Client started.

Troubleshooting

If you experience problems, please check the log file first. If it is not helpful, change the log level to DEBUG and check again. If no error can be seen, please start the AlertR client manually and check if an error occurs that is not printed into the log file. This can be done by just executing the AlertR client as the user that it normally runs with.

alertr@towel:~/alertClientExecuter$ ./alertRclient.py

If you still have problems and do not know how to solve them, you can ask on the community page on reddit or you can use the Github Issues.

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