Everything about nothing

Promjena uvjeta korištenja Google usluga...

2012-02-03T09:30:00.003+01:00

Google je nedavno promijenio uvjete korištenja svojih usluga i o tome je slao obavijesti na različite načine kako bi svatko mogao vidjeti koji su novi uvjeti. Međutim, tko uopće čita uvjete korištenja? ;) I onda se desi nekakav problem i ispadne da je nešto pisali sitnim slovima, ali tko čita uopće sitna slova?! Toliko puta ispričana priča u svakodnevnom životu, ne samo vezano za Internet i

arpwatch on multiple interfaces

2012-01-31T22:51:00.001+01:00

I'm regularly using arpwatch on all servers I install in order to track MAC changes and to notice potential MAC spoofings. But the problem is that on CentOS 6.2 the startup script shipped with arpwatch (arpwatch-2.1a15-14.el6.x86_64) doesn't support multiple interfaces. More specifically, I can tell arpwatch on which interface to listen by modifying OPTIONS variable in /etc/sysconfig/arpwatch

Why we should study history...

2012-01-28T19:44:00.002+01:00

Oh, it happened so many times! I stumbled upon it already while reading John Day's book titled Patterns in network architecture: A return to fundamentals. In short, at one point something is controversial and in next, it's regarded as a some kind of a rule that people passionately protect! One good example is 7-layer ISO/OSI Reference Model. When it was created it was problematic how many layers

Usefull Unix commands, tips and tricks...

2012-01-28T18:52:00.001+01:00

Have you seen this question on Hacker News? It's great and actually there are really some useful commands and tips for use of the command line more efficiently. Here I'll list some of them in case you want a quick glance, but be aware that something mentioned there might already be known to me and/or I decided that it's not so important and excluded it. So, without further ado, here's my list of

Biseri naših neukih novinara 2...

2012-01-27T13:22:00.001+01:00

Eto, nastavak serije bisera potaknut člankom o napadu na Index u Novom listu. Ok, moram priznati da ovaj puta biser nije toliko velik kao prethodni, ali svejedno ga smatram biserom. Međutim, ovom prilikom neću kritizirati samo novinare Novog lista već i Index (iako, praktično gledajući radi se opet o novinarima :)). Citirani članak piše kako je "najpoznatiji" domaći "haker" napao Index i

How to detect your script is started using su...

2012-01-26T14:01:00.000+01:00

I wrote a script that had a problem when started via su command. Actually, this is a script within /etc/profile.d so it is executed when new login shell is executed. I'll write about that problem in another post, but here I'll concetrate on how to detect su command. But before continuing let me clarify that this is a bit of a misnomer. Namely, the goal is to detect whether current environment is

Tvrtki Symantec ukraden izvorni kod...

2012-01-26T13:07:00.000+01:00

Symantecu je ukraden izvorni kod nekih njegovih proizvoda! O tome sada bruji cijeli Internet jer se radi o velikom problemu. Ironija je da proizvođač čija primarna djelatnost je vezana uz sigurnost računala i mreža, i koji bi trebao druge štiti, je sam uspješno napadnut 2006. godine te mu je tom prilikom ukraden izvorni kod nekih njegovih proizvoda. Kradljivci koda prijete da će ga objaviti, no

Kritpiranje diskova - razlozi za i neki pravni problemi...

2012-01-24T10:18:00.000+01:00

Prilično je jasno kako je trend zadnjih nekoliko godina da prijenosna računala zamjenjuju stolna. Više je prednosti prijenosnih računala, ali imaju i jednu veliku manu. Puno lakše ih je izgubiti ili ukrasti nego što je to slučaj sa stolnim računalima. To samo po sebi ne bi predstavljalo veliki problem da se na diskovima ne nalaze tajni podaci koje, iz raznih razloga, ne bi željeli da vide drugi.

Istraga bande iza Koobeface zloćudnog koda...

2012-01-22T23:33:00.000+01:00

This is Croatian translation of text published here. I tried to preserve original content and meaning as much as possible. I recommend that if you know English read the original version. Ovo je prijevod teksta objavljenog na ovoj stranici. Preporučam da prije čitanja ovog teksta pogledate informacije o samom prijevodu. Uvod: ne postoji savršen kiberzločin Koobface botnet - proizvod

Prijevod teksta o istrazi Koobeface zloćudnog koda...

2012-01-22T23:29:00.000+01:00

Danas sam pročitao tekst u kojemu se opisuje istraga koju su obavili Jan Drömeri i Dirk Kollberg i čiji rezultat je bilo otkrivanje pojedinaca koji se nalaze iza Koobeface zloćudnog koda. Kao rezultat te istrage, nakon njenog objavljivanja, kriminalci su se povukli što je popraćeno i kod nas. S obzirom da je taj tekst izuzetno zanimljiv, iz nekoliko razloga, odlučio sam ga prevesti na Hrvatski

Cybercriminal underground - results of an investigation...

2012-01-22T14:05:00.002+01:00

I just finished reading blog post The Koobface malware gang - exposed! This is a fantastic read for a several reasons. First, it shows how one investigation is performed and what information sources were used for that purpose. Next, it shows inner workings of cybercriminal underground which by itself is very very interesting. Finally, it shows also what can be inferred about every individual

Anti-SOPA protest... results...

2012-01-22T00:38:00.002+01:00

This week there was anti-SOPA protest in which several high profile Web sites took part, e.g. Wikipedia, Google, YCombinator, to name a few. I already blogged about SOPA. PIPA appeared in the mean time and I didn't covered it, but in the end I think it's no better than SOPA. The blackout event was also covered by all the media in the world and now, even my parents know there was Wikipedia

Cisco's bug in ARP behavior - A story of firewall configuration oddisey...

2012-01-21T13:47:00.000+01:00

Well, a very interesting situation happened to me. I was changing an old firewall with a new one and after switching I added secondary IP address to a firewall's public interface with the intention that all the traffic that was comming to that secondary IP address is redirected to one internal server. All nice except that it didn't work! I created such configuration numerous times and it simply

Biseri naših neukih novinara 1...

2012-01-21T09:44:00.000+01:00

S vremena na vrijeme naletim na naslov, ili članak, naših vrlih novinara koji jednostavno zrači neizmjernom glupošću i besmislenošću. I to nije baš tako rijetka pojava. Uglavnom, kada naletim na takve stvari napisat ću pokoji post i ovo je prvi u toj seriji. Naslov koji me je inspirirao je Poznati Hrvati na UDARU: Ljubi Jurčiću HAKIRALI karticu s dnevnim limitom od 7000 eura objavljen u

Problem with avformat_open_input()

2012-01-19T17:28:00.002+01:00

I lost too much time because of misleading error message reported by avformat_open_input function! Using the following code: AVFormatContext *pFormatCtx = NULL; ... ret = avformat_open_input(&pFormatCtx, argv[1], NULL, NULL); if (ret < 0) print_error_and_exit(ret, "avformat_open_input()"); Where print_error_and_exit() used function av_strerror() to give textual representation of error code

OSSEC active response...

2012-01-19T14:30:00.000+01:00

This is still work in progress (I need to add more about configuration part). But since OSSEC is so badly documented and I don't know when this will be finished I'm publishing it now. Prompted by the problem caused by the OSSEC active response, I decided to try to debug why an error is occurring in logs and fine tune it. But in order to do that I had first to understand how it works. There is a

Interesting problem with OSSEC, active response and mail delivery...

2012-01-17T14:24:00.000+01:00

We had a problem that manifested itself in such a way that mail messages didn't come from certain domains, or more specifically from certain mail servers. Furthermore, no clue was given in the mail log to know what went wrong and to make things worse, logs from the remote mail server were inaccessible to see there what actually happened. Finally, the worse thing was that this happened

About Git and Perforce..

2012-01-14T15:29:00.003+01:00

All this started with a reading of a simple post why Java is slower that C. This is actually interesting, and controversial, question which I'm going to address in another post, but this time I ended up in reading what different developers are saying about git and perforce. It's also interesting to find out about different repositories that exists, and I mean on those that are proprietary. The

Configuration management...

2012-01-11T17:44:00.000+01:00

Anybody that ever administered more than few machines knows how hard it is to keep them maintained. Especially when you have a mix of different operating systems, and I mean different like Windows, Linux, AIX, HP-UX, etc. For that purpose many different configuration management applications were written, but there is no perfect solution. In case you are running Windows environment, then I have to

Keyboard autorepeat...

2012-01-09T21:47:00.002+01:00

It happens from time to time that keyboard autorepeat suddenly stops working. It just happened to me after I used VMware with Windows 7 within it. I don't believe it's Windows' fault, but VMware's mouse and keyboard driver that allows seamless integration of desktops is probably to blame. Anyway, this is very annoying, when autorepeat doesn't work, so I googled a bit and found out that using '

Problem with inactive agent in OSSEC Web Interface

2011-12-20T14:55:00.000+01:00

I was just debugging OSSEC Web interface. Namely, it incorrectly showed that one host was not responding event though there were log entries that showed otherwise. The problem was that this particular host was transferred to another network, and thus, its address was changed. I figured out that the list of available agents within Web interface is generated from a files found in /var/ossec/queue/

List all tabs across all windows in Firefox...

2011-12-20T10:41:00.001+01:00

I have a lot of windows opened at the same time, and in each window there are many tabs. This makes it a nightmare to find a specific tab; you have to go window by window, and tab by tab. So, I just spent half an hour, maybe more, searching for a way to list all tabs that are opened in all windows. It turns out that there is not much information. In majority of cases you'll find news and tips on

Why I don't believe in God but strongly wish there is one...

2011-12-11T12:28:00.001+01:00

... or in other words, why I'm agnostic. This is related to Christian way of thinking about God, and I suppose that it extends to some other large religions as well. It certainly doesn't cover every possible religion nor it is meant to. I'm not going to discuss every possible religion for a simple reason that I neither have time nor will nor interest to do so. First, let me say that I strongly

Higgs field vs. Higgs particle...

2011-12-10T20:30:00.001+01:00

Well, it turns out that this week there will be a press conference in CERN that will present results of the search for Higgs particle. It could be that the physicists will not find it, or it could be they found some sign of its existence. Anyway, reading article What if there is no Higgs boson, a found a blog with The Higgs FAQ 1.0. If you are not physicists, like me, then I strongly recommend

Evolution & Thunderbird

2011-12-09T11:18:00.001+01:00

I can not describe how much Evolution annoys me! I'm using it for years, maybe 10 or so by now, and I can say with quite a bit of a confidence that it's full of bugs, at least on Fedora, and there was no release in past few years that didn't have some quirks that made me go mad! And today, it happened that it didn't want to create a meeting within a Google calendar with a usual unhelpful error

Problems with resolver library...

2011-12-06T11:48:00.001+01:00

I just had a problem that manifested itself in a very strange way. I couldn't open Web page hosted on a local network, while everything else seemingly worked. The behavior was same for Chrome and Firefox. In due course I realized that every application had this problem. On the other hand, resolving with nslookup worked flawlesly. This was very confusing. To add more to the confusion, while

Compiling Zeitgeist data sources plugins on Fedora 15...

2011-11-29T14:30:00.001+01:00

I'm constantly in search for some way that will help me organize myself. I tend to do many things at once and keeping track of all of them is hard. One of the possibilites I wanted to try for a long time now was Zeitgeist. Basically, Zeitgeist records all your activities and they can be viewed later with gnome-activity-journal application. This system isn't finished yet, for example, it lacks

"Obnovljivi" izvori energije...

2011-11-24T21:44:00.001+01:00

I found a very interesting article about renewable energy sources. Since this article is in English and written very nicely, I don't have much to add (apart from some supportive thoughts on nuclear energy). Anyway, I decided to write a post in Croatian primarily for those that don't know English well. Ja sam jedan od onih koji smatraju da je nuklearna energija najekološkiji mogući pristup

Re-adding SATA disk to software RAID without rebooting...

2011-11-24T12:19:00.001+01:00

It happened second time that on the one of the servers I'm maintaining one of the SATA disks suddenly was disconnected from the server. Looking into log files, I found the following error messages: kernel: mptbase: ioc0: LogInfo(0x31110d00): Originator={PL}, Code={Reset}, SubCode(0x0d00) cb_idx mptbase_reply kernel: mptbase: ioc0: LogInfo(0x31110d00): Originator={PL}, Code={Reset}, SubCode(

Prijevod riječi "enterprise"...

2011-11-24T08:13:00.001+01:00

In this post I'm discussing the possible translation of a word enterprise to Croatian. There is no adequate translation (as far as I know) and I'm suggesting that word enterprise actually means large business system so I'm starting with that premise. Riječ enterprise puno se koristi u Engleskom jeziku i dosta često vidim kako ljudi kada pišu tekst na Hrvatskom koriste tu riječ bez prijevoda,

Some HTML(5) stuff...

2011-11-22T22:37:00.001+01:00

It is no exaggeration to say that HTML5 is a hot stuff. Every now and then something cool pops up that is enabled by HTML5 and modern browsers. So, here in this post I'm going to present the links I collected during some period now. Basically, there will be more than just HTML5, but majority is definitely about HTML5. First, I just finished watching this video. It's some basic stuff/intro to

arping command

2011-11-22T20:38:00.001+01:00

arping command is a very useful Linux command. It's purpose is to send ARP request on the local network and to print received responses. It's a sort like ping command, but it works on layer 2 (data link layer) instead on a network layer like ping. Unlike ping command you have to specify egress interface to this command since otherwise it doesn't know where to send request, and the command itself

My new policy for use of this blog...

2011-11-22T15:30:00.000+01:00

Well, I just managed to clarify to myself several principles that I'm going to follow for using this blog. Those are, in no particular order: I'm going to use this blog as a diary. This means that I'm going to start to write many posts of which majority wouldn't be published for a long period of time. The rule for when some post will be published is simple when it's good enough. In Croatian will

SSH TAP tunnels: Using routing instead of bridging...

2011-11-22T15:00:00.000+01:00

In the previous post about SSH tunneling, I used bridging functionality within Linux kernel in order to connect remote network with local laptop. But it is also possible to use routing in that case. The reason why you would prefer routing, instead of bridging, is the quantity of traffic that might be flowing from the remote network to your interface. And because you are probably connected with

SOPA ilitiga Stop Online Piracy Act...

2011-11-21T15:30:00.001+01:00

This is a post about SOPA. There are many posts, news and other stuff about it on the Web primarily in English, and a lot less in Croation. So I decided to write a post in Croatian, but links are to English sites. Ponekad se doista smatram sretnim što ne živim u Americi. Na žalost, činjenica što ne živim tamo ipak mi ne pomaže puno jer što god Amerikanci napravili, to utječe na sve ostale u

Programmer's blogs...

2011-11-20T20:38:00.001+01:00

There was very interesting question on Hacker News, What programming blogs do you read daily?! Well, that's very interesting question so I read some comments to see, maybe there will be those interesting to me too. For the time beeing here is only (a partial) list of links that were mentioned in the comments. And, someone posted a link to a similar (but more restricted) question on StackExchange

Physics news...

2011-11-20T19:50:00.001+01:00

Very interesting news in physics lately. First, there are news about OPERA team repeating experiments (preprint here), this time with a greater precision and with the same results, i.e. neutrinos arrived sooner than expected. Now even those that were skeptical a becoming cautious, that is, everyone is now waiting for MINOS to repeat experiment so that we get independent results. If MINOS confirms

Interesting fact about card shuffling...

2011-11-19T21:54:00.001+01:00

Every now and then it happens to me that I stumble upon something obvious yet something that didn't occurred to me. This time it was this post. It's about shuffling cards, I and many others did it so many times. Yes, I knew that there are many combinations, but with a little bit of analysis it turns out that there are so many combinations that every shuffle is very likely unique in a history of

NVidia Linux drivers...

2011-11-19T11:20:00.001+01:00

Well, after several hard lockups during past several months and few other bugs in even longer time, I'll be certain next time I buy computer to try very hard to buy one with ATI video card. I can not describe how much I hate binary driver from NVidia, and by extension, NVidia! Here is why I hate it: I have to manually install it. This means that every time either kernel or X driver is updated,

Zimbra 7 and domain wide disclaimer...

2011-11-17T13:43:00.001+01:00

In Zimbra 7 it is not necessary any more to hack scripts in order to get domain wide disclaimer. At least not if you want to add the same disclaimer to every mail that passes through your mail server. In case you want more control, like not attaching it to some mails, then you'll have to resort again to scripts and hacking. So, to add disclaimer, the following would do: zmprov mcf

UIF format i MagicISO alat...

2011-11-17T10:28:00.001+01:00

Upravo sam skinuo nekakvu datoteku s Interneta i ispostavilo se da je pohranjena u formatu UIF (bar je takva ekstenzija bila u pitanju). U takvim slučajevima koristim naredbu file, koja je instalirana na skoro svakom Unixu, te koja ispisuje o čemu se radi, uglavnom dovoljno da znam što dalje. Međutim, u ovom slučaju nije prepoznala datoteku, što se vidi po tome jer u opisu ispisuje data. Nakon

MagicISO and uif format...

2011-11-17T10:20:00.001+01:00

I just stumbled on some file that was written in uif format. Linux's file command doesn't recognize it but google-fu quickly revealed a tool to convert uif format into iso image. This is a command line tool that works on both Linux and Windows. Now, I suggest that you read uif2iso.txt file that is embedded into the archive. It turns out that uif format was made up by some Chinese guy who

SSH VPNs: Bridged connection to LAN using tap

2011-11-14T12:46:00.001+01:00

In the previous post I showed how to create SSH tunnel that ends on a network layer (ppp and point-to-point types) and on a link layer (ethernet type). Now I'm continuing with a series of scenarios that do configuration on a network layer (and few on a link layer too). This is the first scenario in which I want remote host to look like it is directly attached to a local network. The network

Tunneling everything with SSH... or how to make VPNs...

2011-11-11T08:25:00.001+01:00

In the previous three posts I described how to use OpenSSH to tunnel traffic for different applications. What all those three techniques had in common was that they tunneled only TCP traffic and that every time the connection was initiated from the local machine, i.e. in a way it was not possible for the machine on the other side to transfer data to us (actually, it is possible to circumwent some

More about Steve Jobs...

2011-11-09T17:48:00.001+01:00

A lot has been written about Steve Jobs many of which were simply to idealistic. I just found this article that, it seems to me, better explains Jobs' character, virtues, but also deficiencies. This article actually cites a lot from Steve Jobs' biography written by Isaacson. Anyway, the truth is that Jobs, no matter what we think about him, did achieve something special and interesting thing is

Using multiple instances of Firefox...

2011-11-03T10:02:00.001+01:00

Firefox has a great feature called Profiles. You can use them to have multiple instances of a browser. If you wonder why would you use something like that, here are few reasons: you might want to separate professional from private browsing, or to have development or hacking environment distinctive from "usual" environment. you might want to try out some new plugin without messing up your

20 years of vim

2011-11-02T19:53:00.001+01:00

Wow, I just stumbled on this article on Ars technica (via Hacker News). This article celebrates 20 years of Vim, an vi clone. I have to say I exclusively use vi (Vim actually, but in compatibility mode) for all my editing, or almost all, this post wasn't written in vi. ;) The first time I used vi was in 1990, or something like that, but it was only for a short period of time when I had an

New developments in CentOS world...

2011-11-02T14:30:00.001+01:00

Suddenly, there is a flurry of news about CentOS. First, there was some lengthy discussion on CentOS user's mailing list about the current state of the 6.1 release and about the RedHat versus CentOS. Also, on a development mailing list there is discussion about moving CR repository back to main repository. Finally, there was a question on Slashdot about why would someone use RedHat when there is

Examples of ovaldi checks: sysctl variables

2011-10-31T12:25:00.000+01:00

After I described how to compile ovaldi on CentOS and a simple test to verify it is working, in this post I'm going to describe how to use ovaldi to check the values of sysctl variables. More precisely, I'm going to check that IPv4 forwarding is turned off. The general idea behind this example is to give you a starting example on which you can build more complicated checks. Note that there is

Testing ovaldi on CentOS 6...

2011-10-31T00:22:00.003+01:00

In the previous post I described how to compile ovaldi for CentOS. In the mean time I tested that installation and found few more bugs in rpm handling code: query format was wrong, i.e. the tag used was %{SIGGPG:pgpsig} but actually it should be %{SIGPGP:pgpsig}. I tested this on CentOS 6 and Fedora 15 and on both the second form is right. The first form returns (none). After obtaining signature

Compiling OVALDI for CentOS 6

2011-10-30T20:29:00.000+01:00

I described in one earlier post the purpose of OVAL and the benefits it gives to a user. Here I'm going to describe how to setup OVAL interpreter on CentOS 6. The problem is that there is no prepackaged Oval interpreter for CentOS 6. Actually, there is but it's only for 32 bit version of CentOS 4 and 5, an it is an older version, not the latest one. So, here I'm going to describe how to build it

The rise and fall of the great companies...

2011-10-30T18:46:00.001+01:00

It is very interesting to read news about Apple's and ARM's successes on the market on the one hand, and the fall and strugle of some of the undisputed rulers of computing and consumer markets of the not so distant past. Actually, I first think about computing markets, but since it seems that computing market penetrated consumer market and it's hard to distinguish the two, I'll treat them

Installing minimal CentOS 6.0 distribution

2011-10-28T17:31:00.000+02:00

This post starts a three part series in which I'll describe in detail how to install Zimbra mail server on 64-bit CentOS distribution. The first part deals with CentOS installation itself. The second part will talk about setting up split DNS server, and finally, the third part will talk about setting up Zimbra server itself. Before describing installation, I'm going to define the environment,

Installing and testing ovaldi on Windows 7...

2011-10-25T11:18:00.000+02:00

When you are dealing with a single computer with a particular operating system, it is relatively easy to keep it safe. But, as the number of machines grows and becomes more heterogeneous, keeping them safe becomes very donating task. You may have automated updates and such, but they have to be checked from time to time in order to see if they function correctly. Still, if those computers are used

rsync files from cd...

2011-10-21T20:08:00.001+02:00

I just started rsync to copy files from CD ROM. This was a usual form I use: rsync -av source destination But this time I ended up with some error messages and not a single file or a directory was copied. The error messages were like the following ones: rsync: recv_generator: mkdir "/home/user/CD_final/ns-3-dev/bindings" failed: Permission denied (13)*** Skipping any contents from this failed

How to resume download in Firefox...

2011-10-18T09:25:00.001+02:00

I started a large download in Firefox and it turned out to be very slow. Since I was downloading from Oracle, I was probably given "wrong" mirror to download from. So, I was thinking about stopping this particular download and resuming later but I didn't want to lose what I already had. The problem was that it seemd that the Firefox doesn't support that particular scenario, at least not without

Pizzerija Orogoro

2011-10-16T21:30:00.001+02:00

Eto, bio i ja u Orogoro pizzeriji pa da podijelim dojmove sa svekolikim pučanstvom. Ako vas samo zanima konačno mišljenje, to je: osrednje. Ako vas ne zanima mišljenje, to je vaš problem. :) A sada nešto dulje. Kada dođete do same pizzerije, sa ceste izgleda malo, neugledno, ali i zanimljivo. Međutim, onda shvatite da ima cestica koja vodi na parkiralište iza same pizzerije i kada dođete tamo

Dennis Ritchie died...

2011-10-13T08:38:00.000+02:00

Well, another great figure of computing has prematurely left us, according to reports on the Internet. This one isn't so well known like Steve Jobs, but his work certainly matches the one done by Jobs, and in my humble opinion, even exceeds it. His "problem", sort to speak, is that he did everything in the core area of computer science, not in the consumer part, and he did majority of his work

The first use of the term "protocol" in networking...

2011-10-07T12:42:00.002+02:00

I'm just reading the book Where wizards stay up late - The origins of the Internet and in there I found a statement about the first use of the term protocol to denote the rules to be followed in order for computers to be able to exchange information, i.e. to communicate. Everything happened in 1965 when Tom Marill, psychologist by formal education, proposed to ARPA an experiment of connecting

Steve Jobs...

2011-10-06T14:40:00.001+02:00

Internet is full of news about the premature death of Steve Jobs, after all he was only 56 years old! And no matter what we think about Apple, or maybe even Steve Jobs, we have to agree that he, and the company he founded, made a significant mark on many lives, actually even more than that, in a way, he changed our culture. I was reading what others have said about Jobs, most notably Bill Gates,

Otvoreni kod i taktika zauzimanja tržišta...

2011-10-04T20:00:00.000+02:00

Dosta često se nađem u raspravi u kojoj pokušavam objasniti kako je otvoreni kod dobra taktika da se neki proizvod proširi na već ustaljenom tržištu, i to pogotovo kada je taj proizvod napravila mala tvrtka koja nema odgovarajuće (čitati: velike) distribucijske kanale. Naravno da je nužni preduvijet za sve to dovoljno veliko tržište i/ili zanimljiv i koristan proizvod. U ovom postu pokušat ću

Yet more fun with SSH tunnels... accessing forbidden Web pages...

2011-10-04T15:04:00.000+02:00

This is very interesting and simple hack, and analogous to SMTP one. or inverse version of Web access. Suppose that you want to access some Web site that is blocked by a firewall in your local network where you reside. In case you have some machine outside the local network (and of course, SSH isn't disabled) that you can access blocked Web site. I'll assume that the IP address of that outside

More fun with ssh tunnels... accessing Web

2011-10-04T09:32:00.000+02:00

Suppose that you have some Web application and you can access it only from local network, either because firewall on the host itself protects access or there is firewall at the network perimeter. Either way, you are currently somewhere on the Internet and you have to access this application, e.g. some administrative interface. In my case, I have Zimbra Web administrative console access confined

Installing Snort 2.9.1 on 64-bit CentOS 6...

2011-10-01T13:08:00.000+02:00

I just installed Snort 2.9.1 on CentOS 6, and since that wasn't straightforward process, I decided to document all the steps I did for a later reference. Also, maybe someone will find this useful so I placed it here. The process of setting up Snort is divided into three phases, compilation, installation and configuration. Compilation phase is done entirely on auxiliary host, while installation

Captcha and few variants...

2011-09-30T12:35:00.000+02:00

I'm downloading some stuff from the Internet, and as a part of that process I had to solve captcha in order to prove that I'm a human. Captcha can be thought of as a puzzle that have to be solved and, by assumption, only a human can solve it. But, the reality is that there are automated ways that can solve capthcas, particularly badly designed ones. So, I was thinking a bit about captcha and

Why I think it is in RedHat's interest to help CentOS...

2011-09-29T10:34:00.000+02:00

Today I was asked if there are any security implications in selecting particular licensing model from Microsoft. Basically, I know nothing about that particular subject, and as far as I can remember from some previous experiences, this is something that requires specialization in itself. To cut the story short, I don't intend to waste my time in studying Microsoft's licensing models! So, in the

CentOS... something is happening!

2011-09-27T15:45:00.001+02:00

I just noticed that RPM packages from RHEL 6.1 appeared on mirrors. Actually, they announced it few days earlier but that was sooner that I was expecting. :) There is a small catch. In order for yum to be able to catch those packages you'll have to add new repository. Namely, CentOS team decided to go with a mechanism they call Continuous updates. In that way they'll try to be faster, but, time

Privatnost na Internetu - Uvod i osnove

2011-09-25T19:37:00.002+02:00

Ponukan postovima ovakvog tipa odlučio sam početi pisati malo i o zaštiti privatnosti na Internetu i to na hrvatskom jeziku te što je moguće razumljivije ljudima kojima Internet nije struka. Naime postova na engleskom jeziku ima mnoštvo, ali mislim da ih je na hrvatskom puno manje, ako ih uopće i ima. Prvenstveno namjera mi je objasniti načine na koje se ljude može pratiti dok surfaju, iako ću se

Faster than light?!

2011-09-23T18:45:00.001+02:00

This is really hot! For a past few days there are news about neutrinos going faster than a light. I spent past few hours on this, i.e. watching webcast, searching the Net and reading blogs. I wanted to read/hear opinions from all the possible sides, not just the one, and especially not from some half-informed journalists. I also wanted to understand as much as possible, which is unfortunately not

Komercijalna podrška otvorenom kodu u Hrvatskoj

2011-09-23T13:38:00.001+02:00

Već dulje vremena me kopka jedna misao. Naime, čini mi se kako je problem s otvorenim kodom u Hrvatskoj kako nema odgovarajuće podrške. Pod odgovarajućom podrškom mislim na dovoljno veliku tvrtku koja je sposobna pružiti usluge na cijelom teritoriju Republike Hrvatske i to s prilično striktnim SLA. Potencijalni korisnici, a to su prvenstveno velike tvrtke (pod tim mislim na velike tvrtke za

Implementing IF, AND, OR, etc. in iptables...

2011-09-22T09:54:00.000+02:00

I saw that some people accessed my blog while searching for OR, AND, IF and similar operators in iptables. These operators are indeed implemented within the subsystem but not in the usual sense, that is, they are not so obvious. In other words, they are implicit in the way you are writing rules. But, if you understand how that works, writing iptables rules becomes much easier. Before continuing

OpenSSH and how to get around port 25 filters on local networks...

2011-09-20T16:01:00.000+02:00

OpenSSH is a very capable tool and I'm using it for years. And even though I don't consider myself a beginner user, but rather an advanced one, every now and then I learn something new about this great tool. Here are two links to such sites that I found to be very interesting: SSH Can Do That? Productivity Tips for Working with Remote Servers 9 Awesome SSH Tricks Be sure to also read comments

CentOS 6.1...

2011-09-15T10:02:00.001+02:00

... or not! Ok, before I continue, first a disclaimer. This is my personal view of the whole situation around CentOS. If you disagree, that's ok. If you wish you can argue via comments, but please, keep to the point and give arguments for you statements. Don't troll. Oh, and if you spot grammatical and similar errors, please email me corrections. So, this whole situation is frustrating, a lot!

iOS versus Android...

2011-09-13T08:35:00.001+02:00

Well, there are two approaches to develop smart phone OS. The first one is Apple's way and that is to control everything. The other one is Google's way and that is to control (almost) nothing. My personal opinion is that Apple's way is better for people that don't know anything about computers and thus someone else has to make choices for them. Of course, Google's way is better for those that

Implementing Turing machine using iptables...

2011-09-10T17:02:00.000+02:00

Ok, today I decided that I'm going to try to implement Turing machine using iptables. From the start it was obvious to me that I'll use stream of IP packets as a tape. So, after reading a bit and thinking, I decided to implement this Turing machine. The reason I selected that particular one is because tape always moves to the right, and that simplifies things a lot. More precisely, I decided to

Nastanak novca i dug...

2011-09-10T12:56:00.002+02:00

Danas sam naletio na jedn zanimljiv intervju. Mislio sam da se radi o razjašnjavanju pojma duga države o kojemu se stalno priča, ali je na kraju ispalo da se radi o nečemu širemu, a uključuje između ostalog i pitanje kako je nastao novac. U školi su nas učili kako je prvotni način trgovanja bila trampa te da je novac izmišljen kao posljedica neadekvatnosti trampe (Imaš kravu i trebaš moje

CAs are broken... but... there may be a fix...

2011-09-01T12:57:00.001+02:00

Everyone by now heard of security breach of DigiNotar. The Internet is full of stories about it! I won't go into details what happened. Instead, I'll try to pinpoint what actual problem is, and, based on that, I'll try to outline possible solution. Let us start with the problem. The problem is that every single CA is actually single point of failure of the whole distributed system. Do you need

Implementing if statement in iptables

2011-03-18T15:08:00.002+01:00

It just occurred to me that user defined chains in iptables are actually equivalent of an if statement. Namely, if you need to do something like the following: if (packet meets certain criteria) { ... } then you'll actually do it so that anything between curly braces will be placed in user defined chain, while test if packet meets certain criteria would be iptables command that uses -j

Search for complexity measure and where it took me...

2011-03-10T21:47:00.003+01:00

Well, I got very interested in complex systems lately. So, I decided to write a paper for a local conference in which I tried to join information security with complexity. A part of this endeavor made me to Google for a paper that describes complexity measure. Well, I found many interesting things, but not what I was looking for, at least not yet. Still, I wanted to preserve some of those

Logging: Do they think?

2010-11-02T12:44:00.001+01:00

Last week I had to discover the reason for some obscure log entry in ESXi vmkernel log. It looks something like this: Nov 2 11:34:36 vmkernel: 16:21:06:29.145 cpu2:2446675)WARNING: UserObj: 569: Failed to crossdup fd 6, fs: def5 oid: 19000000030000003 type CHAR: Busy Do I need to say that I found nothing? This is very nice entry, on which, if you try to use your best google-fu, you'll end up

Software patching strategy...

2010-06-11T21:26:00.000+02:00

There's much controversy about security flaw found in Windows XP and published by Google's researcher. You can read about it across the Internet, but here's one story. Short version is this: after the researcher found the flaw he gave Microsoft five days to react. But, Microsoft has something called 'patch Tuesday' which means it is delivering patches every Tuesday. I agree that this brings

Kako izabrati Web stranice za tvrtku?

2009-11-01T13:51:00.002+01:00

Već neko vrijeme si razmišljam kako bi mogao započeti pisati nekakvu vrstu konzultantske miniserije, tj. upute što napraviti u određenim nabavkama i modernizacijama IT infrastrukture. Ideja ne nedostaje, primjerice VoIP, Web stranice, VPN, DMS, poslužiteljska infrastruktura, itd. Kod svih ovih nabavki karakteristika je da tvrtka dobavljač/izvođač u općem slučaju ima kao svoj cilj maksimizirati

Malo filozofije...

2009-08-19T22:51:00.003+02:00

Tu i tamo uhvati me minuta razmišljanja o "smislu života" i ponekad mi na pamet padne pitanje koje mi se čini toliko očitim, a s tim i vrlo vjerojatnimda se pitam kako se toga nisam ranije sjetio. No ipak, ne mogu tvrditi kako sam se sam dosjetio tih pitanja, lako je moguće da sam ih negdje vidio u nekom obliku i potom potisnuo u podsvjest. No, sigurno je da bez obzira vidio ih ili ne, nisam prvi

ESXi 4

2009-06-02T09:27:00.003+02:00

VMware released free version of it's supervisor ESXi 4 somewhere around the previous weekend. I managed to install it into VMware Workstation and to give it a quick try. Until I have more to say, here are a few differences that I noted during and immediatelly after installation process finished:Minimum of 2GB RAM in order to be installed and used. I tried to lower memory size after installation

Security through obscurity - is it useless?

2008-07-31T09:13:00.004+02:00

For a few weeks now I've been thinking about security through obscurity (STO). It is a common wisdom that it's a bad way to build security of anything. But, this doesn't have to be necessarily true, as I'll explain in the moment. What made me write this post is that a similar comment about usefulness of STO was given in a Matt Bishop's artice in IEEE Security & Privacy journal (About Penetration

The critique of dshield, honeypots, network telescopes and such...

2008-07-13T19:31:00.005+02:00

To start, it's not that those mechanisms are bad, but what they present is only a part of the whole picture. Namely, they give a picture of the opportunistic attacks. In other words, they monitor behavior of automated tools, script kiddies and similar attackers, those that do not target specific victims. The result is that not much sophistication is necessary in such cases. If you can not

Reputations for ISP protection

2008-07-06T01:25:00.005+02:00

Several serious problems this year made me think about security of the Internet as a whole. Those particular problems were caused by misconfigurations in BGP routers of different Internet providers. The real problem is that there are too many players on the Internet that are treated equally even though they are not equal. This causes all sorts of the problems and it is hard to expect that those

Studentska posla...

2008-02-19T08:30:00.003+01:00

Uvijek mi je drago pročitati koju studentsku raspravu o smislu života. Može se tu doista čuti svega i svačega, nađe se ponešto istine, al' kao i kod naših novinara, nađe se i podosta izvrnutih, ili bolje rečeno "prilagođenih" izjava za potrebe tekuće rasprave. Nije nam bez veze novinarstvo u takvom stanju kakvom je...No, da se vratim raspravi o smislu života. Dakle, baš kao i u svakoj drugoj

New Internet architecture, my take at it no. 1

2008-02-08T16:57:00.000+01:00

Reading all those papers about new Internet architecture simply doesn't give me peace. What is the solution? Probably it is a simple one in a concept, though , as always, the devil is in the details. Look at the Internet now. When it was first proposed to use packet switching it looked like lunatics' idea and now it's so normal we don't even think about it and take it for granted. So, it's

DDoS attacks, Internet, new Internet and POTS...

2008-02-05T21:53:00.000+01:00

I was just thinking about many initiatives (e.g. GENI) to design Internet from scratch! It certainly requires us to break out from the current way of thinking, that's with us for about 40 years now, and to find and propose something new. The good example of this break through was the Internet itself, i.e. the concept of packet switched network. As a side note, Van Jacobson has an idea of how

Amerika... zemlja daleka...

2007-10-08T18:21:00.000+02:00

Naslov baš i nije nešto originalan, stalno mi zvoni u glavi, al' se nikako ne mogu sjetiti odakle. (Da, sad će vjerojatno neko preporučiti da odem psihijatru zbog zvonjave u glavi, al' to je pod kontrolom :)). Svejedno, bijah u Americi nekih desetak dana i pun sam dojmova. U ovom postu skoncentrirat ću se na neke stvari koje su drastično različite od nas. Da li su one pozitivne ili ne,

Biseri...

2007-10-08T17:44:00.000+02:00

Dugo već nisam ništa pisao, al' to je čisto posljedica nedostatka vremena. Nije da ga je i sad u izobilju al' moram opisati jedan događaj koji se zbio prije nekih mjesec dana. Jednostavno, takve gluposti se ne zaboravljaju lako. Još sam se u međuvremenu i smirio koliko sam bio nervozan kad se sve to odigralo.Dakle, sve je krenulo od neke reportaže (ili nečeg u tom stilu) na nekoj od domaćih TV

Buying on eBay in Croatia...

2007-06-08T12:54:00.000+02:00

I wrote a page about my buying experiences on eBay. Because I intend to expand this page I thought it's better to place it on my homepage. Furthermore, because this is specific to Croatia I wrote it in Croatian and not in English. This blog entry is to announce this page, and also to create place for comments!So, post your thoughts, questions, ... I think we can comment on Croatian since this is

OSS support for Croatian language

2007-01-28T12:49:00.000+01:00

I was just looking at the Asterisk open source PBX and one of the features of that software is possibility of integration with Festival. Festival is a text to speech synthesis software, freely available on the Internet! And it's quite good piece of software. Using only Festival, or Festival in combination with some other application, like Asterisk, interesting services could emerge.Now, we come

VIP UMTS/EDGE/whatever...

2007-01-27T22:12:00.000+01:00

Ok, I prepared this post while I was trying to connect to the Internet and I was very angry! For the problems I have I blame VIP and this post summarizes my experiences with them. I doubt that the others are different. And yes, for those that don't know, VIP is Internet provider in Croatia.To buy the card and subscription was the least problem and it was quick. Although, I heard that now they

“You will work on the newest technologies”

2007-01-14T15:58:00.000+01:00

The title of this entry is actually taken from one ad searching for prospective students to work in a Croatian telecom after graduating. Actually, ad itself is very cleverly thought out and I have to give credit to the one who thought of it. But, there is always doubt that it was actually “taken” from someone else...What's important about this sentence is how little it actually says and how

BGPlay and whois...

2007-01-04T15:51:00.000+01:00

And here comes first "serious" post. :) It's about handy tool called BGPlay.The purpose of this tool is to visualize AS connectivity in time from some point in the Internet to the given network/AS. Actually, it's Java applet, and you can find it here. I didn't saw link where source, or application, can be downloaded.First of all, let me try to explain briefly what AS is. Internet consists of

My first entry, something about design...

2007-01-04T15:33:00.000+01:00

So, I just managed to chose template. The simpler the better. The other problem is that currently I'm using UMTS/GPRS to access Internet and it's sloooooooooow! And that's enough to make me very nervous. So, no fancy features for now. Anyway, in time I hope I'll customize these pages better.And I'm still figuring out what can I do with this blog system.