Posts Tagged ‘threat’

Merry Christmas from Pomorie Monastery and a small monastic fire that ended well

Thursday, December 26th, 2013


I spend the Christmas eve for a first time in Monastery with the brotherhood in Pomorie monastery. The night on 24-th against 25-th when Christmas is celebrated in Bulgaria was marked by the usual morning service and a Holy Liturgy. Silent Night Holy Night song was sung in the Church near the end of the Holy Liturgy.

All went well except small fire incident, out of a suddenr right after the end of the Church service a fire ignited  in one of the monastery store rooms. Actually it was a huge miracle that the fire didn't spread in whole monastic cell buildings as the fire used to be active without anyone noticing it for about 6 hours or so. The restult of fire was that  just one room full of sheets and sanitary equipment burn out completely. The fire happened in a room nearby my room on second stage one stage lower (on first floor). The fire brigade come quickly and stashed the fireplace without serious troubles.

The fire would have quickly spread if in the burning room if only one of the water tubes didn't break up pouring water inside on the burning stuff. The fire emerged around 12:40 and was already еxtinguished for less than hour. Thanks God there was no one in the burning room and no victims  Another sure miracle is that today weather is very calm no wind blowing so fire didn't ignited in a quick pace and was easily extinguished.  

Below are the immersly beautiful Christmas Church Troparion, Kontaktion and Feast singings as translated to English

Thy nativity, O Christ our God,
has shown to the world the light of wisdom;
for by it, those who worshipped the stars
were taught by a star to adore Thee
the Sun of Righteousness,
and to know Thee, the Orient from on high.
O Lord, glory to Thee."

Today the virgin, gives birth to the incomprehensible One;
and the earth offers a cave to the unapproachable One;
Angels and shepherds glorify Him;
the Wisemen journey with a star;
since for our sakes is born the ETERNAL GOD, as a little Child.

Christ is born, glorify him.
Christ is from heaven, go to meet him.
Christ is an earth, be ye lifted up.
Sing to the Lord, all the earth.
Sing out with gladness, all ye people.
For he is glorified.

To the Son begotten of the Father
without change before the ages,
and in these last times without seed made flesh from a Virgin,
to Christ God let us cry aloud:
Thou hast exalted our horn. Holy are Thou, O Lord!'

Rod of the root of Jesse,  and flower that blossomed from his stem, O Christ,
Thou hast sprung from the Virgin.
From the Mountain overshadowed by the forest
Thou hast come, made flesh from her that knew not wedlock,
O God who art not formed from matter.
Glory to Thy power, O Lord.

As Thou art God of peace and Father of mercies,
Thou hast sent us Thy Angel of great counsel,
Who grants us peace;
so we are guided by the knowledge of God,
watching before dawn we glorify Thee, only Lover of mankind'.

The monster from the deep
spat Jonas from its bowels like a new born babe,
just as it had received him;
while the Word having dwelt in the Virgin and taken flesh,
came forth, yet kept her incorrupt,
for being himself not subject to decay,
he preserved his mother free from harm'.

The Youths brought up together in godliness,
scorning the impious decree,
feared not the threat of fire,
but standing in the midst of the flame they sang:
God of our Fathers, blessed are Thou!

The furnace moist with dew was the image and the figure of a wonder past nature;
for it did not burn those it had received;
even as the fire of the Godhead
did not consume the Virgin's womb into which it has descended.
Therefore in praise let us sing:
Let all creation bless the Lord,
and highly exalt Him to all the ages.

Magnify, O my soul, the most glorious Theotokos,
more honourable and more glorious than the hosts on high.
'I behold a strange and wonderful mystery,
heaven is the Cave, the Cherubim thrown — Virgin,
the Manger the Place in which Christ lay,
the God whom nothing can contain. Whom we praise and magnify.

I wish to my dear readers have a great and blessed Christmas Holiday time, let Christ's love, peace and mercies are abundant in your hearts!

How to convert AVI, MP4, FLV (flash video) and other non-free video encoded formats to Free Video format encoding OGV (Ogg Vorbis / Theora) on GNU / Linux and FreeBSD

Thursday, November 17th, 2011

Ogg Vorbis Free / Open Audio Video Format logo

I was looking for a way to convert some Video and Sound files, downloaded from Youtube (mostly things dedicated to free software) and as far as I looked online unfortunately these pieces of nice music and tutorials are not available for download anywhere else or at least not available for download in some of the Open / Free Format (OGG Vorbis or OGV (OGG / Theora Video).

When it comes to convertion between different formats, always the first things that I think of is ffmpeg or mencoder , however I was not sure if some of this tools are doing the trick so I did a quick research online if there is some specialised console or GUI program that can do the convertions between MP4, FLV etc. to OGV.

In less than 10 minutes I found a threat mentioning about ffmpeg2theoraA Simple Convertor to create Ogg Theora files

As I’m running Debian GNU / Linux, I installed ffmpeg2theora straight via apt, according to some reports online ffmpeg2theora cmd convertion tool is also available straight from repositories on Ubuntu as well.
On FreeBSD there is a port /usr/ports/multimedia/ffmpeg2theora available for install. Of course FFmpeg2Theora can be installed from source on other Linux distributions that might be missing a pre-built binary.

Using ffmpeg2theora to convert some kind of non-free video format is very simple, though the tool provides quite a numerous options for all those who want to have some customization for the video to be converted.
To convert the flash file “The Gnu Song.flv” for example to The Gnu Song.flv , I invoked ffmpeg2theora like this:

debian:~# ffmpeg2theora "The Gnu Song.flv"

The conversion took few minutes of time, as my machine is not ultra powerful and apparently the conversion to OGV format is not too quick but the good news is it works.
After the conversion was completed I used ogginfo to check the information about the recent converted file The Gnu Song.flv , below you see the file info ogginfo returns

debian:~# ogginfo The Gnu Song.ogv
Processing file "The Gnu Song.ogv"...

New logical stream (#1, serial: 5d65413f): type skeleton
New logical stream (#2, serial: 0570412d): type theora
New logical stream (#3, serial: 7e679651): type vorbis
Theora headers parsed for stream 2, information follows…
Version: 3.2.1
Vendor: Xiph.Org libtheora 1.1 20090822 (Thusnelda)
Width: 320
Height: 240
Total image: 320 by 240, crop offset (0, 0)
Framerate 25/1 (25.00 fps)
Aspect ratio undefined
Colourspace: Rec. ITU-R BT.470-6 Systems B and G (PAL)
Pixel format 4:2:0
Target bitrate: 0 kbps
Nominal quality setting (0-63): 32
User comments section follows…
Vorbis headers parsed for stream 3, information follows…
Version: 0
Vendor: Xiph.Org libVorbis I 20101101 (Schaufenugget)
Channels: 1
Rate: 22050
Nominal bitrate: 30.444000 kb/s
Upper bitrate not set
Lower bitrate not set
User comments section follows…
Logical stream 1 ended
Theora stream 2:
Total data length: 1525324 bytes
Playback length: 2m:41.360s
Average bitrate: 75.623401 kb/s
Logical stream 2 ended
Vorbis stream 3:
Total data length: 646729 bytes
Playback length: 2m:41.384s
Average bitrate: 32.059041 kb/s

ogginfo is a part of a package installed under the name vorbis-tools, vorbis tools also contains a few other helpful tools, whether operations with OGV or OGG file formats are at hand, the complete binaries vorbis-tools contains on Debian as of time of writting this post is:


ogg123 is a player for ogg files, however as far as I’ve tested it it doesn’t work too well. And just to compare ogg audio files were played just nice using the play command.
oggenc is used to encode ogg audio file, based on a stream haneded to it from other audio encoded stream (let’s say mp3). Hence oggenc can be used to convert mp3 files to ogg audio files , like so:

debian:~# mpg321 input.mp3 -w - | oggenc -o output.ogg -

oggdec is used to convert to wav files or raw PCM audio, whether;
vcut is used to cut ogg video file on parts.
vorbiscomment and vorbistagedit is used to edit information on already existing ogg audio files

There is also a GUI programmer for people who doesn’t want to bother with writting on the command line called oggconvert . OggConvert is written for GNOME and uses GTK gnome library, here is how the program looks like:

OggConvert GUI Program to convert to OGG og OGV Theora on GNU / Linux and FreeBSD


Downloading your favourity flash video from Youtube with a simple command (youtube-dl)

Wednesday, April 13th, 2011

Watching videos in youtube today and already for about 2 years is the de-facto hype.
There is almost none a day passed without almost each one of us has watched a dozen videos in Youtube.

Watching videos in youtube has become even more addictive for many than the early days of Internet Relay Chats (IRC)

As youtube is very accessible for people and it’s a comparativily easy way people share more and more with the day.
There is no question that the business idea of youtube is great and youtube generates millions of dollars for Google day by day, however I have a serious objection here! All is good the only pitfall is that you don’t own the youtube videos you watch!

Youtube’s story is not that different from the story of the cloud computing threat to internet users Freedom

The good thing here is that we’re not still completely dependant on youtube and there is still way to retrieve your favourite youtube video and store it for later watching or distribution.

Probably the most famous browser plugin that allows files retrieval from youtube, as most people know is DownloadHelper .

However using download helper is browser dependant, you need to use the browser to save the plugin and I don’t find it to be the best way to download a youtube video.

Since the old days I have started using Linux, I’ve been quite addicted to as many things on my linux as possible from the command line (terminal / console) (CLI) .

In that manner of thoughts it was a real delight for me to find out that a group of free software developer guys has come up with a command line tool that allows downloads of youtube videos straight from terminal, the great software is called youtube-dl and at the moment of this post writting it’s to be found on the URL address:

Youtube-dl is written in python so, it requires the Python interpreter, version 2.5 in order to properly run on Unix, Mac OS X or even on Windows!

The fact that it’s written in python has made the little shiny tool quite a multi-platform one.
To start using immediately the tool on a Debian or Ubuntu Linux you will have to install python (even though in most cases you must have it already installed):

1. To make sure you have python interpreter installed issue the cmd:

debian:~# apt-get install python
Building dependency tree
Reading state information... Done
python is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

As you can see from above apt-get’s output I do have it installed so nothing gets installed.

2. As a next step I used links to download the youtube-dl python script, like so:

debian:~# links >> youtube-dl
Use the links interface to save youtube-dl and use gzip to ungzip it
debian:~# gzip -d youtube-dl.gz
debian:~# chmod +x youtube-dl

Now to make it system wide accessible I have copied the youtube-dl to /usr/local/bin , whether I selected /usr/local/bin as a location as this location is predetermined to contain mostly files which does not belong to a regular deb package.

3. Move youtube-dl to /usr/local/bin

debian:~# mv youtube-dl /usr/local/bin

4. Test the newly installed youtube-dl command line youtube retrieval tool:

debian:~# ./youtube-dl
[youtube] Setting language
[youtube] g7tvI6JCXD0: Downloading video webpage
[youtube] g7tvI6JCXD0: Downloading video info webpage
[youtube] g7tvI6JCXD0: Extracting video information
[download] Destination: g7tvI6JCXD0.flv
[download] 53.3% of 22.62M at 33.23k/s ETA 05:25
[download] 100.0% of 22.62M at 31.91k/s ETA 00:00 [u

As you might have noticed from the above youtube-dl command output the newly retrieved youtube file will be saved under a name g7tvI6JCXD0.flv

The line I passed to youtube-dl is directly taken from my browser and pasted to console, the file downloading from youtube took me about 10 minutes but this is mostly because of some kind of youtube server speed restrictions …

In general at least I have this video for later, watching, so after a while I can watch it once again without loosing a lot of time trying to remember what was the video headline name

5. To use youtube-dl in a bit advanced way you can for instance invoke the command with options like:

debian:~# ./youtube-dl -l -w -c
[youtube] Setting language
[youtube] g7tvI6JCXD0: Downloading video webpage
[youtube] g7tvI6JCXD0: Downloading video info webpage
[youtube] g7tvI6JCXD0: Extracting video information
[download] Destination: BSD is Dying, Jason Dixon, NYCBSDCon 2007-g7tvI6JCXD0.flv
[download] 4.4% of 22.62M at 1.43M/s ETA 00:15

As you can see now youtube-dl was even able to detect the downloaded video file name and store it on the computer with a correct name 😉

I would recommend you also to check out the youtube-dl help page, to do use command: youtube-dl –help

Maximal protection against SSH attacks. If your server has to stay with open SSH (Secure Shell) port open to the world

Thursday, April 7th, 2011

Brute Force Attack SSH screen, Script kiddie attacking
If you’re a a remote Linux many other Unix based OSes, you have defitenily faced the security threat of many failed ssh logins or as it’s better known a brute force attack

During such attacks your /var/log/messages or /var/log/auth gets filled in with various failed password logs like for example:

Feb 3 20:25:50 linux sshd[32098]: Failed password for invalid user oracle from port 51490 ssh2
Feb 3 20:28:30 linux sshd[32135]: Failed password for invalid user oracle1 from port 42778 ssh2
Feb 3 20:28:55 linux sshd[32141]: Failed password for invalid user test1 from port 51072 ssh2
Feb 3 20:30:15 linux sshd[32163]: Failed password for invalid user test from port 47481 ssh2
Feb 3 20:33:20 linux sshd[32211]: Failed password for invalid user testuser from port 51731 ssh2
Feb 3 20:35:32 linux sshd[32249]: Failed password for invalid user user from port 38966 ssh2
Feb 3 20:35:59 linux sshd[32256]: Failed password for invalid user user1 from port 55850 ssh2
Feb 3 20:36:25 linux sshd[32268]: Failed password for invalid user user3 from port 36610 ssh2
Feb 3 20:36:52 linux sshd[32274]: Failed password for invalid user user4 from port 45514 ssh2
Feb 3 20:37:19 linux sshd[32279]: Failed password for invalid user user5 from port 54262 ssh2
Feb 3 20:37:45 linux sshd[32285]: Failed password for invalid user user2 from port 34755 ssh2
Feb 3 20:38:11 linux sshd[32292]: Failed password for invalid user info from port 43146 ssh2
Feb 3 20:40:50 linux sshd[32340]: Failed password for invalid user peter from port 46411 ssh2
Feb 3 20:43:02 linux sshd[32372]: Failed password for invalid user amanda from port 59414 ssh2
Feb 3 20:43:28 linux sshd[32378]: Failed password for invalid user postgres from port 39228 ssh2
Feb 3 20:43:55 linux sshd[32384]: Failed password for invalid user ftpuser from port 47118 ssh2
Feb 3 20:44:22 linux sshd[32391]: Failed password for invalid user fax from port 54939 ssh2
Feb 3 20:44:48 linux sshd[32397]: Failed password for invalid user cyrus from port 34567 ssh2
Feb 3 20:45:14 linux sshd[32405]: Failed password for invalid user toto from port 42350 ssh2
Feb 3 20:45:42 linux sshd[32410]: Failed password for invalid user sophie from port 50063 ssh2
Feb 3 20:46:08 linux sshd[32415]: Failed password for invalid user yves from port 59818 ssh2
Feb 3 20:46:34 linux sshd[32424]: Failed password for invalid user trac from port 39509 ssh2
Feb 3 20:47:00 linux sshd[32432]: Failed password for invalid user webmaster from port 47424 ssh2
Feb 3 20:47:27 linux sshd[32437]: Failed password for invalid user postfix from port 55615 ssh2
Feb 3 20:47:54 linux sshd[32442]: Failed password for www-data from port 35554 ssh2
Feb 3 20:48:19 linux sshd[32448]: Failed password for invalid user temp from port 43896 ssh2
Feb 3 20:48:46 linux sshd[32453]: Failed password for invalid user service from port 52092 ssh2
Feb 3 20:49:13 linux sshd[32458]: Failed password for invalid user tomcat from port 60261 ssh2
Feb 3 20:49:40 linux sshd[32464]: Failed password for invalid user upload from port 40236 ssh2
Feb 3 20:50:06 linux sshd[32469]: Failed password for invalid user debian from port 48295 ssh2
Feb 3 20:50:32 linux sshd[32479]: Failed password for invalid user apache from port 56437 ssh2
Feb 3 20:51:00 linux sshd[32492]: Failed password for invalid user rds from port 45540 ssh2
Feb 3 20:51:26 linux sshd[32501]: Failed password for invalid user exploit from port 53751 ssh2
Feb 3 20:51:51 linux sshd[32506]: Failed password for invalid user exploit from port 33543 ssh2
Feb 3 20:52:18 linux sshd[32512]: Failed password for invalid user postgres from port 41350 ssh2
Feb 3 21:02:04 linux sshd[32652]: Failed password for invalid user shell from port 54454 ssh2
Feb 3 21:02:30 linux sshd[32657]: Failed password for invalid user radio from port 35462 ssh2
Feb 3 21:02:57 linux sshd[32663]: Failed password for invalid user anonymous from port 44290 ssh2
Feb 3 21:03:23 linux sshd[32668]: Failed password for invalid user mark from port 53285 ssh2
Feb 3 21:03:50 linux sshd[32673]: Failed password for invalid user majordomo from port 34082 ssh2
Feb 3 21:04:43 linux sshd[32684]: Failed password for irc from port 50918 ssh2
Feb 3 21:05:36 linux sshd[32695]: Failed password for root from port 38577 ssh2
Feb 3 21:06:30 linux sshd[32705]: Failed password for bin from port 53564 ssh2
Feb 3 21:06:56 linux sshd[32714]: Failed password for invalid user dev from port 34568 ssh2
Feb 3 21:07:23 linux sshd[32720]: Failed password for root from port 43799 ssh2
Feb 3 21:09:10 linux sshd[32755]: Failed password for invalid user bob from port 50026 ssh2
Feb 3 21:09:36 linux sshd[32761]: Failed password for invalid user r00t from port 58129 ssh2
Feb 3 21:11:50 linux sshd[537]: Failed password for root from port 58358 ssh2

This brute force dictionary attacks often succeed where there is a user with a weak a password, or some old forgotten test user account.
Just recently on one of the servers I administrate I have catched a malicious attacker originating from Romania, who was able to break with my system test account with the weak password tset .

Thanksfully the script kiddie was unable to get root access to my system, so what he did is he just started another ssh brute force scanner to crawl the net and look for some other vulnerable hosts.

As you read in my recent example being immune against SSH brute force attacks is a very essential security step, the administrator needs to take on a newly installed server.

The easiest way to get read of the brute force attacks without using some external brute force filtering software like fail2ban can be done by:

1. By using an iptables filtering rule to filter every IP which has failed in logging in more than 5 times

To use this brute force prevention method you need to use the following iptables rules:
linux-host:~# /sbin/iptables -I INPUT -p tcp --dport 22 -i eth0 -m state -state NEW -m recent -set
linux-host:~# /sbin/iptables -I INPUT -p tcp --dport 22 -i eth0 -m state -state NEW
-m recent -update -seconds 60 -hitcount 5 -j DROP

This iptables rules will filter out the SSH port to an every IP address with more than 5 invalid attempts to login to port 22

2. Getting rid of brute force attacks through use of hosts.deny blacklists

sshbl – The SSH blacklist, updated every few minutes, contains IP addresses of hosts which tried to bruteforce into any of currently 19 hosts (all running OpenBSD, FreeBSD or some Linux) using the SSH protocol. The hosts are located in Germany, the United States, United Kingdom, France, England, Ukraine, China, Australia, Czech Republic and setup to report and log those attempts to a central database. Very similar to all the spam blacklists out there.

To use sshbl you will have to set up in your root crontab the following line:

*/60 * * * * /usr/bin/wget -qO /etc/hosts.deny

To set it up from console issue:

linux-host:~# echo '*/60 * * * * /usr/bin/wget -qO /etc/hosts.deny' | crontab -u root -

These crontab will download and substitute your system default hosts with the one regularly updated on , thus next time a brute force attacker which has been a reported attacker will be filtered out as your Linux or Unix system finds out the IP matches an ip in /etc/hosts.deny

The /etc/hosts.deny filtering rules are written in a way that only publicly known brute forcer IPs will only be filtered for the SSH service, therefore other system services like Apache or a radio, tv streaming server will be still accessible for the brute forcer IP.

It’s a good practice actually to use both of the methods 😉
Thanks to Static (Multics) a close friend of mine for inspiring this article.

Cloud Computing a possible threat to users privacy and system administrator employment

Monday, March 28th, 2011

Cloud Computing screenshot

If you’re employed into an IT branch an IT hobbyist or a tech, geek you should have certainly heard about the latest trend in Internet and Networking technologies the so called Cloud Computing

Most of the articles available in newspapers and online have seriously praised and put the hopes for a better future through cloud computing.
But is really the cloud computing as good as promised? I seriously doubt that.
Let’s think about it what is a cloud? It’s a cluster of computers which are connected to work as one.
No person can precisely say where exactly on the cluster cloud a stored information is located (even the administrator!)

The data stored on the cluster is a property of a few single organizations let’s say microsoft, amazon etc., so we as users no longer have a physical possession of our data (in case if we use the cloud).

On the other hand the number of system administrators that are needed for an administration of a huge cluster is dramatically decreased, the every day system administrator, who needs to check a few webservers and a mail server on daily basis, cache web data with a squid proxy cache or just restart a server will be no longer necessary.

Therefore about few million of peoples would have to loose their jobs, the people necessary to administrate a cluster will be probably no more than few thousands as the clouds are so high that no more than few clouds will exist on the net.

The idea behind the cluster is that we the users store retrieve our desktops and boot our operating system from the cluster.
Even loading a simple webpage will have to retrieve it’s data from the cluster.

Therefore it looks like in the future the cloud computing and the internet are about to become one and the same thing. The internet might become a single super cluster where all users would connect with their user ids and do have full access to the information inside.

Technologies like OpenID are trying to make the user identification uniform, I assume a similar uniform user identication will be used in the future in a super cloud where everybody, where entering inside will have access to his/her data and will have the option to access any other data online.

The desire of humans and business for transperancy would probably end up in one day, where people will want to share every single bit of information.
Even though it looks very cool for a sci-fi movie, it’s seriously scary!

Cloud computing expenses as they’re really high would be affordable only for a multi-national corporations like Google and Microsoft

Therefore small and middle IT business (network building, expanding, network and server system integration etc.) would gradually collapse and die.

This are only a few small tiny bit of concerns but in reality the problems that cloud computing might create are a way more severe.
We the people should think seriously and try to oppose cloud computing, while we still can! It might be even a good idea if a special legislation that is aming at limiting cloud computing can be integrated and used only inside the boundary of a prescribed limitations.

Institutions like the European Parliament should be more concerned about the issues which the use of cloud computing will bring, EU legislation should very soon be voted and bounding contracts stop clouds from expanding and taking over the middle size IT business.