Posts Tagged ‘data security’

Zabbix: Monitor Linux rsyslog configured central log server is rechable with userparameter script

Wednesday, June 8th, 2022


On modern Linux OS servers on Redhat / CentOS / Fedora and Debian based distros log server service is usually running on the system  such as rsyslog (rsyslogd) to make sure the logging from services is properly logged in separate logs under /var/log.

A very common practice on critical server machines in terms of data security, where logs produced by rsyslog daermon needs to be copied over network via TCP or UDP protocol immediately is to copy over the /var/log produced logs to another configured central logging server. Then later every piece of bit generated by rsyslogd could be  overseen by a third party auditor person and useful for any investigation in case of logs integrity is required or at worse case if there is a suspicion that system in question is hacked by a malicious hax0r and logs have been "cleaned" up from any traces leading to the intruder (things usually done locally by hackers) or by any automated script exploit tools since yesr.

This doubled logging of system events to external log server  ipmentioned is very common practice by companies to protect their log data and quite useful for logs to be recovered easily later on from the central logging server machine that could be also setup for example to use rsyslogd to receive logs from other Linux machines in circumstances where some log disappears just like that (things i've seen happen) for any strange reason or gets destroyed by the admins mistake locally on machine / or by any other mean such as filesystem gets damaged. a very common practice by companies to protect their log data.  

Monitor remote logging server is reachable with userparameter script

Assuming that you already have setup a logging from the server hostname A towards the Central logging server log storepool and everything works as expected the next logical step is to have at least some basic way to monitor remote logging server configured is still reachable all the time and respectively rsyslog /var/log/*.* logs gets properly produced on remote side for example with something like a simple TCP remote server port check and reported in case of troubles in zabbix.

To solve that simple task for company where I'm employed, I've developed below

# @@ for TCP @ for UDP
# Script to check if configured TCP / UDP logging server in /etc/rsyslog.conf is rechable
# report to zabbix

PORT=$(grep -Ei "*.* $DELIMITER.*:$GREP_PORT" /etc/rsyslog.conf|awk -F : '{ print $2 }'|sort -rn |uniq);

#for i in $(grep -Ei "*.* $DELIMITER.*:$GREP_PORT" /etc/rsyslog.conf |grep -v '\#'|awk -F"$DELIMITER" '{ print $2 }' | awk -F ':' '{ print $1 }'|sort -rn); do
HOST=$(grep -Ei "*.* $DELIMITER.*:$GREP_PORT" /etc/rsyslog.conf |grep -v '\#'|awk -F"$DELIMITER" '{ print $2 }' | awk -F ':' '{ print $1 }'|sort -rn)

# echo $PORT

if [[ ! -z $PORT ]] && [[ ! -z $HOST ]]; then
SSH_RETURN=$(/bin/ssh $HOST -p $PORT -o ConnectTimeout=$CONNECT_TIMEOUT 2>&1);
echo "PROBLEM Port $GREP_PORT not defined in /etc/rsyslog.conf";

#exit 1;
if [[ $(echo $SSH_RETURN |grep -i ‘Connection timed out during banner exchange’ | wc -l) -eq ‘1’ ]]; then
echo "rsyslogd $HOST:$PORT OK";

if [[ $(echo $SSH_RETURN |grep -i ‘Connection refused’ | wc -l) -eq ‘1’ ]]; then
echo "rsyslogd $HOST:$PORT PROBLEM";

#sleep 2;

You can download a copy of the script here

Depending on the port the remote rsyslogd central logging server is using configure it in the script with respective port through the DELIMITER='@@', GREP_PORT='5145', CONNECT_TIMEOUT=5 values.

The delimiter is setup as usually in /etc/rsyslog.conf this the remote logging server for TCP IP is configured with @@ prefix to indicated TCP mode should be used.

Below is example from /etc/rsyslog.conf of how the rsyslogd server is configured:

[root@Server-hostA /root]# grep -i @@ /etc/rsyslogd.conf
# central remote Log server IP / port
*.* @@

To use the script on a machine, where you have a properly configured zabbix-agentd service host connected and reporting data to a zabbix-server monitoring server.

1. Set up the script under /usr/local/bin/

[root@Server-hostA /root ]# vim /usr/local/bin/

[root@Server-hostA /root ]# chmod +x /usr/local/bin/

2. Prepare userparameter_check_log_server.conf with log_server.check Item key

[root@Server-hostA zabbix_agentd.d]# cat userparameter_check_log_server.conf 
UserParameter=log_server.check, /usr/local/bin/

3. Set in Zabbix some Item such as on below screenshot


check-log-server-status-screenshot-linux-item-zabbix.png4. Create a Zabbix trigger 


The redded hided field in Expression field should be substituted with your actual hostname on which the monitor script will run.

Install and use personal Own Cloud on Debian Linux for better shared data security – OwnCloud a Free Software replacement for Google Drive

Thursday, August 23rd, 2018


Basicly I am against the use of any Cloud type of service but as nowadays Cloud usage is almost inevitable and most of the times you need some kind of service to store and access remotely your Data from multiple devices such as DropBox, Google Drive, iCloud etc. and using some kind of infrastructure to execute high-performance computing is invitable just like the Private Cloud paid services online are booming nowdays, I decided to give a to research and test what is available as a free software in the field of Clouding (your data) 🙂

Undoubfully, it is really nice fact that there are Free Software / Open Source alternatives to run your Own personal Cloud to store your data from multiple locations on a single point.

The most popular and leading Cloud Collaboration service (which is OpenSource but unfortunately not under GPLv2 / GPV3 – e.g. not fully free software) is OwnCloud.

ownCloud is a flexible self-hosted PHP and Javascript based web application used for data synchronization and file sharing (where its remote file access capabilites are realized by Sabre/Dav an open source WebDav server.
OwnCloud allows end user to easily Store / Manage files, Calendars, Contacts, To-Do lists (user and group administration via OpenID and LDAP), public URLs can be easily, created, the users can interact with browser-based ODF (Open Document Format) word processor , there is a Bookmarking, URL Shortening service integrated, Gallery RSS Feed and Document Viewer tools such as PDF viewer etc. which makes it a great alternative to the popular Google Drive, iCloud, DropBox etc.

The main advantage of using a self-hosted Cloud is that Your data is hosted and managed by you (on your server and your hard drives) and not by some God knows who third party provider such as the upmentioned.
In other words by using OwnCloud you manage your own data and you don't share it ot on demand with the Security Agencies with CIA, MI6, Mussad … (as it is very likely most of publicly offered Cloud storage services keeps track on the data stored on them).

The other disadvantage of Cloud Computing is that the stored data on such is usually stored on multiple servers and you can never know for sure where your data is physically located, which in my opinion is way worse than the option with Self Hosted Cloud where you know where your data belongs and you can do whatever you want with your data keep it secret / delete it or share it on your demand.

OwnCloud has its clients for most popular Mobile (Smart Phone) platforms – an Android client is available in Google Play Store as well as in Apple iTunes besides the clients available for FreeBSD OS, the GNOME desktop integration package and Raspberry Pi.

For those who are looking for additional advanced features an Enterprise version of OwnCloud is also available aiming business use and included software support.

Assuming you have a homebrew server or have hired a dedidacted or VPS server (such as the Ones we provide) ,Installing OwnCloud on GNU / Linux is a relatively easy
task and it will take no more than 15 minutes to 2 hours of your life.
In that article I am going to give you a specific instructions on how to install on Debian GNU / Linux 9 but installing on RPM based distros is similar and straightfoward process.

1. Install MySQL / MariaDB database server backend

By default OwnCloud does use SQLite as a backend data storage but as SQLite stores its data in a file and is becoming quickly slow, is generally speaking slowre than relational databases such as MariaDB server (or the now almost becoming obsolete MySQL Community server).
Hence in this article I will explain how to install OwnCloud with MariaDB as a backend.

If you don't have it installed already, e.g. it is a new dedicated server install MariaDB with:

server:~# apt-get install –yes mariadb-server

Assuming you're install on a (brand new fresh Linux install – you might want to install also the following set of tools / services).


server:~# systemctl start mariadb
server:~# systemctl enable mariadb
server:~# mysql_secure_installation

mysql_secure_installation – is to finalize and secure MariaDB installation and set the root password.

2. Create necessery database and users for OwnCloud to the database server

linux:~# mysql -u root -p
MariaDB [(none)]> CREATE DATABASE owncloud CHARACTER SET utf8;
MariaDB [(none)]> GRANT ALL PRIVILEGES ON owncloud.* TO 'owncloud'@'localhost' IDENTIFIED BY 'owncloud_passwd';
MariaDB [(none)]> \q


3. Install Apache + PHP necessery deb packages

As of time of writting the article on Debian 9.0 the required packages for a working Apache + PHP install for OwnCloud are as follows.


server:~# apt-get install –yes apache2 mariadb-server libapache2-mod-php7.0 \
openssl php-imagick php7.0-common php7.0-curl php7.0-gd \
php7.0-imap php7.0-intl php7.0-json php7.0-ldap php7.0-mbstring \
php7.0-mcrypt php7.0-mysql php7.0-pgsql php-smbclient php-ssh2 \
php7.0-sqlite3 php7.0-xml php7.0-zip php-redis php-apcu


4. Install Redis to use as a Memory Cache for accelerated / better performance ownCloud service

Redis is an in-memory kept key-value database that is similar to Memcached so OwnCloud could use it to cache stored data files. To install latest redis-server on Debian 9:

server:~# apt-get install –yes redis-server

5. Install ownCloud software packages on the server

Unfortunately, default package repositories on Debian 9 does not provide owncloud server packages but only some owncloud-client packages are provided, that's perhaps the packages issued by owncloud does not match debian packages.

As of time of writting this article, the latest available OwnCloud server  version package for Debian is OC 10.

a) Add necessery GPG keys

The repositories to use are provided by, to use them we need to first add the necessery gpg key to verify the binaries have a legit checksum.

server:~# wget -qO- | sudo apt-key add –


b) Add repositories in separete sources.list file


server:~# echo 'deb /' | sudo tee /etc/apt/sources.list.d/owncloud.list


c) Enable https transports for the apt install tool


server:~# apt-get –yes install apt-transport-https


d) Update Debian apt cache list files and install the pack


server:~# apt-get update


server:~# apt-get install –yes owncloud-files


By default owncloud store file location is /var/www/owncloud but on many servers that location is not really appropriate because /var/www might be situated on a hard drive partition whose size is not big enough, if that's the case just move the folder to another partition and create a symbolic link in /var/www/owncloud pointing to it …

6. Create necessery Apache configurations to make your new self-hosted cloud accessible

a) Create Apache config file


server:~# vim /etc/apache2/sites-available/owncloud.conf



Alias /owncloud "/var/www/owncloud/"

<Directory /var/www/owncloud/>
Options +FollowSymlinks
AllowOverride All

<IfModule mod_dav.c>
Dav off

SetEnv HOME /var/www/owncloud
SetEnv HTTP_HOME /var/www/owncloud


b) Enable Mod_Dav (WebDAV) if it is not enabled yet


server:~# ln -sf ../mods-available/dav_fs.conf
server:~# ln -sf ../mods-available/dav_fs.load
server:~# ln -sf ../mods-available/dav.load
server:~# ln -sf ../mods-available/dav_lock.load

c) Set proper permissions for /var/www/owncloud to make upload work properly


chown -R www-data: /var/www/owncloud/

d) Restart Apache WebServer (to make new configuration affective)



server:~# /etc/init.d/apache2 restart

7. Finalize  OwnCloud Install

Access OwnCloud Web Interface to finish the database creation and set the administrator password for the New Self-Hosted cloud


By default the Web interface is accessible in unencrypted (insecure) http:// it is a recommended practice (if you already don't have an HTTPS SSL certificate install for the IP or the domain to install one either a self-signed certificate or even better to use LetsEncrypt CertBot to easily create a valid SSL for free for your domain



Just fill in in your desired user / pass and pass on the database user / password / db name (if required you can set also a different location for the data directory from the default one /var/www/owncloud/data.

Click Finish Setup and That's all folks!


OwnCloud is successfully installed on the server, you can now go and download a Mobile App or Desktop application for whatever OS you're using and start using it as a Dropbox replacement. In a certain moment you might want to consult also the official UserManual documentation as you would probably need further information on how to manage your owncloud.

Enjoy !

How to improve your web browser security – Better securing your personal identity privacy on the Net

Monday, August 2nd, 2010

Nowadays internet privacy has become a taboo. Many people do understand how vital is it to protect your privacy online.
Unfortunately not much has done much in order to improve their state of security whilst on the net.
In this article you’re about to find out how trusted and secure is the browsing in the Internet and next to it you will find some possibleways and thoughts how you can improve your personal privacy and the amount of information your browser reveals about your (habits, interestest, and, lifestyle) while surfing online.
There are a lot of private information that can leak through a simple web serarch, let’s say you decide to search for some kind of sickness and it’s treatment.. just few minutes later the paid advertisement popping up will be showing up targetting ads related to your previous sickness google search.
This is tiny bit of information your browser reveals, however there is much much more. So let me give you a few more examples:
Let’s say you visit a website with an Adobe Flash browser player enabled. It’s very likely that the website will have flash advertisement this popular this day. If that is the scenario it’s very likely that the flash application is built to use тхе so called flash cookies supported.
You might have never heard about flash cookies but anyways this one of cookies are one of the most malicious cookies ever invented.
One of the main reason they’re so dubious is the fact THEY NEVER EXPIRE!
Though as with normal cookies flash cookies are used for storing user details, let’s say your profile details or settings concerning your youtube video player etc. and this sound nice, market guys use the same features to track what you do online.
Using flash cookies for instance everybody who cratefted a specific adobe flash page is able to list your flash cookies stored browser history!
To partly setup the behaviour of your Flash player and change the defailt flash player settings for good use the flashplayer settings manager

It’s really odd that the only way to configure flash is to configure it via adobe’s webpage this is much sneaky since, God only knows what kind of information as well probably your whole flash browser history and flash cookies is being sent Adobe for later analysis.
Moreover the flash player is a propriatary software and this makes it even more likely to have included some extra spying software and stuff alike ..

To see all the stored information by flash about a websites you have visited check out:

flashplayer settings manager

Honestly I was quite shocked when I saw many websites I have visited for the rest 1.5+ year listed.

From hence since we know how “evil” flash storage manager cookies are, one sure step to increase your browser privacy is to periodically get rid of Flash Storage (Flash Cookies).
To achieve periodical flash cookies wipe out on Linux, below I provide you with a tiny .tcsh script which is tested and is working on Debian and Ubuntu. Get rid of Local Flash Storage shell script for Linux
(Stores data of the websites you have visited using your browser flash player)

To check your general Browser security The Electronic Frontier Foundation has developed a special website to test your browser anonymity visit and click the > TEST ME button

In my case all my installed browser plugins were listed as well many information related to what kind of browser I use the version on the architecture I’m running on etc. etc.
Thereafter navigate to about:config and set the variable to false . This will completely disable the DOM cookies which by the way never expire!
DOM cookies aren’t so widely used yet but still it’s possible that some websites online has stareted using them, since they’re completely junky and bad designed for instance DOM a cookie can contant up to (100KB) of information. then it’s best that you disable them completely.
Another recommendable thing to disable on your Iceweasel / Firefox that will tighten up your security is the keyword.enabled variable click twice on it and assure yourself it reads false
Disabling it will prevent the google word suggest to appear each time you type something in Google search box, albeit not every character you type will be sent to Google.

Also a really nice worthy reading is the article explaining dom cookies
Take some time and read it to get a better idea on DOM cookies what they are and why you don’t want them.
Likewise take a look at Flash Cookie Forensics for a bit more insight on the flash cookies

After reading the article about flash cookies, I came to the conclusion that maybe it’s best that they’re completely enabled. Anyways if they’re disabled then many websites won’t work properly which is something we don’t want.
It’s rather strange that the only available way to control your flash and disable the flash cookies is via Flashplayer Web Based Setting Manager
Since it’s “Web Based Manager” and it is hosted on Adobe’s web site this probably means that everything you do through it gets logged by Adobe, not so nice (neither secure) heh ..

It’s recommended also to install and configure the following list of extra Firefox plugins to ensure a bit more Anonimity while surfing on the Internet.

  • Adblock Plus
  • AntiSocial
  • BeeFree
  • Beef Taco
  • BetterPrivacy
  • DownloadHelper
  • Download Statusbar
  • Live HTTP Headers
  • No FB Tracking
  • NoScript
  • RefControl

Now configure AdBlock plus to work with EasyPrivacy+EasyList (by default it works only with EasyList).
To subscribe for ABP EasyPrivacy click here

BeeFree Mozilla Addon .
Is under the GNU GPL license and it helps you defend a bit more your privacy. It’s advantage use is to prevent search engines from knowing which links from their search results is most probably for you to check. Looks like a promising and great stuff
It is said in the add-on website that as a side effect of using the plugin it will probably increase your browser speed.
This post has highly adopted information from the Bulgarian Article by Anton Zinoviev, 2010 About your web browser and the inviolability of your personal life
Big thanks to Anton Zinoviev for the time and effort taken to research on the topic of browser security and write this wonderful thoroughful article.
To configure the BeeFree Firefox security tightening browser addon you will have to type in your browser URL address bar once again
Now you will have to look up for the following browser config keys:

Set it’s value to be 2 e.g. extensions.beefree.websites.default.header.accept-charset.action = 2
Now look for the key value extensions.beefree.websites.default.header.accept-charset.value.text and set it’s value to:
Changing the extensions.beefree.websites.default.header.accept-charset.action = */* will make BeeFree compatible to some securing anti spam programs.
Last thing to do to complete the BeeFree configuration create the key value
To create this one press on a random key the last mouse button and select New -> Integer
The value for the newly created should be set to 4
Creating this key will instruct beefree to protect your browser from revealing it’s browser version variable.
Interesting to say each restart of the browser will make BeeFree to select a random Firefox Linux or Windows version, dependant of the OS type you use.

The AntiSocial addon will prevent your browser from revealing information to Facebook about your personal interests. It blocks the facebook elements which are being embedded to your browser by some websites.

No FB Tracking stops facebook of keeping an eye on you through the buttons “I like”. Using this buttons facebook can track you even if you’re not logged in or registered in the social network.

Installing all this plugins would take you time but considering the privacy is invaluable time shouldn’t be a concern of you.
Also some of the plugins like NoScript make take some time until you’re used to it but it’s worth to learn using it.
BetterPrivacy is able and will delete all flash cookies when your browser exits, this will prevent that some sites pry on you through the shitty flash cookies technology, this type of cookies NEVER EXPIRE! Hard to swallow but a fact …

In Linux this plugin is reported to work correctly however, in Windows there are dubious reports about it.
This is just a brief overview about how to improve your browsing privacy and therefore general personal data security, there is plenty much already red and said on topic, however I hope this could be some kind of basis for my dear reader for a later research on the topic.