Disconnecting wireless clients from access points The problem The nature of wireless networking is quite problematic because transmission goes over air and can be intercepted by anyone. Of course there is data packet stream encryption. But deauthentication frames are not encrypted and can be forged. It’s applicable to IEEE 802.11 standard. However if your device is capable of 802.11w standard amendment then the management frames are protected from forging, however in various devices this option is disabled by default even if they support it. In case of your device check manual for default settings. It’s worth enabling this option. Not
Detecting and preventing threats Introduction To provide security in a network you can deploy IDS or IPS systems. The difference is on the second letter, D stands for detection and P for prevention. First you start a system in IDS mode and only then you configure it to become IPS system. Enabling Suricata in IPS mode from the start could be confusing. It is advisable to see what’s going on first on a network to be sure not to generate too many false-positive alerts and blocks. Why IDS/IPS? You may ask why do I need intrusion detection or prevention system.
Display geo location map for NGINX traffic logs in Kibana Summary There are 3 things to remember and configure in order to have geo location map working: Use “forwardfor” option on pfSense HAProxy TLS frontend Enable filebeat NGINX module and point particular log files Define custom NGINX log format This guide relates to Ubuntu Linux setup. Elasticsearch 7 First install Elasticsearch 7 as follows. Note: for more resilent setup install more than one Elasticsearch server node and enable basic security. For sake of clarity I will skip these two aspects which will be covered by another article. Kibana Then install
Among 3 million public IP address ranges for the whole world, 68k belongs to the Russian Federation. This translates into 45 million addresses. Scanning the HTTP port on this population took 20 hours. I obtained 630k IP addresses with listening on port 80. Of which 530k gives the correct answer of the HTTP type. Only 340k gives an HTTP 200 response. Over 200k run on NGINX servers, and 100k run on Apache. When analyzing the content, you will find GitLab, Kibana, Zabbix or Grafana installations open for registration and use, but also copies of databases, video surveillance systems, etc. My
The basis for the construction of diodes and transistors A semiconductor is a material whose electrical conductivity is between the conductors and insulators. Their resistance and conductivity depends on temperature and admixtures. [W] The most commercially used semiconductors are those based on silicon, and in the past also on germanium. In addition to these two elements (in crystalline form), a whole spectrum of other substances from groups 13-15 is used, which can form two, three or four-element compounds. P-n junction The basic element of a semiconductor system [003] Additions of atoms of other elements are used to obtain the increased
Energy in a magnetic field [209] Just as a capacitor works by storing energy as an electric field, an inductor stores energy as a magnetic field. The energy stored in the coil is calculated in terms of current. The capacitor acts as an insulator of the circuit while the inductor acts as its conductor. The coils have inductance expressed in henry [H]. The coils are plugged into the circuit in series with the powered device. The coils are characterized by a maximum current, as their windings have a certain resistance, therefore the flow of current causes a voltage to accumulate
I will start with the werid experience with one of WP themes – Polite and Polite Grid. I was wondering why my website make double requests on every page. One for the document and other for content. This was annoying as I was unable to measure traffic properly. It turned out that it was because of the theme I’ve been using for some time. Changing it to different one fixed it. Second of all to make NGINX logs easier to handle I’ve created separate location entry for all the WP things, so the “real” traffic goes only to particular log
Lowering the voltage value [202] The next example I want to present in practice is a popular voltage divider. It allows the output voltage to be reduced to the desired value due to the properties described a little earlier. Bearing in mind the above formula, we can assume that we want to reduce the input voltage of 5V to the expected 2.5V at the output. So we use two 1K resistors connected in series. Examples available at https://github.com/michalasobczak/simple_hpc/tree/master/SeriesPartOne
Theory and practice [W] One of the basic principles of current flow is the first law of Kirchhoff, which says that for the electric circuit node, the algebraic sum of flow rates is zero. The sum of currents flowing into the node is equal to the sum of currents flowing out of this node. This law results from the principle of keeping the load. Kirchhoff’s second law says that the sum of voltage drops in a closed circuit is zero, assuming that the voltage drop is its negative increase. [202] For the purposes of illustrating the law of Kirchhoff, I