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Availability is one pillar of the Information Security; it defines itself as the capability of being accessed by legit users when needed. On the other hand, we have DoS attacks which attack an asset availability. A successful DoS attack is the one that will not let a user access an asset when needed.

Exposures to DoS attacks are not the easiest to discover; a vulnerability scan will not report them. A successful DoS attack does not always exploit a vulnerability. DoS attacks are discovered easily by seasoned security practitioners. For example, an attacker could send millions of HTTP request to a valid URL in a given website. The HTTP request could be totally valid and legit, but what it makes it an attack is the excess of it. The HTTP server cannot handle it, therefore when a legit user tries to access it, he will fail; the HTTP server is too busy.

There could be many kinds of DoS attacks. This article will prevent the following:

  • When an attacker requests too many times the same URL
  • When an attacker request too many times different URL's; each individual type of request may no be considered an attack, but the sum of them it is.

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SIA Coin is the cryptocurrency that allows you to do some earnings by renting your spare hard disk space. In order to be able to rent your space, you must configure some parameters (some of them technical, some others economical). These parameters help the SIA environment to assign a score; the way the score is assigned is complex. I have spent some code reading and I have found the following:

  1. Select the node that is in the n = total_active_hosts * 3 / 5 place. Instead of using the median that uses the element in the middle (1 / 2), SIA uses the 3 / 5.
  2. a correction factor is calculated using the estimated score of the host selected from the first step. c = 1 / estimated_score. The estimated score is given by the SIA API.
  3. All other active hosts' estimated score is multiplied by the correction factor in order to get a score.

Please note that I am not a golang coder. I may have some misreadings. What it is not really clear to me is how the estimated score is calculated (es(X) = n). SIA Coin documentation says it is a combination of prices, uptime, free space, and other things. But they haven't documented (yet) exactly the math behind that number. Again, I am not a golang coder.

When a renter looks for space, the renter will select those hosts with the highest score. So the big question, what parameters can I adjust in order to have a higher score and start doing some profits?

Well, thank god the genetic algorithms exist.

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If you are a CentOS fan as I am, you will find in the need to get some updates on some software as Node.JS. After spending around 400 hrs, I have finally published NodeJS 10.13 RPM for CentOS 7 in the OKay's RPM repository. Node.JS is a JavaScript runtime built on Chrome's V8 JavaScript engine.

Because of the lack of time, and that I really don't use CentOS 6, I did not spend the time to make this available in the sixth release of CentOS. If someone needs it, I would gladly do it if sponsored.