Developers Club geek daily blog

How to calculate range of communication on the equipment Ubiquiti. New version of the AirLink calculator

2 years ago


At the choice of the wireless equipment Ubiquiti each user asks standard questions: What speed can be received at this distance? What model of the equipment it is better to select? Whether it is possible to organize wireless link in general?

For the answer to these questions Ubiquiti Networks offers visual and intuitively clear online service – AirLink |outdoor wireless link calculator.

Read more »


As WiFi breaks loose, or Without wires and leads

2 years ago


It is necessary to write about really important news shortly and clearly: now for small (to 25 points) WiFi-networks based on Ruckus it is not necessary to buy either the controller, or licenses. In general. If it is interesting, how exactly to build the network managed by WiFi without controller – welcome under kat.

Read more »


Two providers at the same time or Dual ISP with VRF on Cisco

2 years ago
image

Hello.
There is a universal solution for connection of several providers, ip sla + track. A solution easy for understanding and simple in management. But when business reaches simultaneous use of two and more communication channels, this technology in pure form does not approach.

I want will share the experience. On nodes with several providers I use the configuration containing virtual routers – VRF. This configuration is taken from my practice and well proved.

Read more »


Virtual network interface

2 years ago
It is well-known that Linux drivers are modules of a kernel. All drivers are modules, but not all modules — drivers. An example of one of such groups of the modules which are not drivers, and much more rare appearing in discussions, surge filters at the different levels of a network stack Linux are.

Sometimes, and it is even rather frequent, it would be desirable to have the network interface which could operate with a traffic of any other interface, but somehow in addition "color" this traffic. It can it is required for the additional analysis, either traffic observation, or its enciphering, …

The idea is extremely simple: to canalize a traffic of already existing network interface in the newly created interface with absolutely other characteristics (a name, IP, a mask, a subnet, …). We will also discuss one of methods of execution of such actions in the form of Linux kernel module (it not only, but we will discuss other methods separately another time).

Read more »


The counterfeit base station for $1400 allows to define precisely location of phone in 4G/LTE of a network

2 years ago


Researchers developed an inexpensive method of detection of exact location of the smartphone working in LTE/4G of a cellular network. This development lets know that mobile networks of new generations are also vulnerable to some types of attacks, as well as the networks working on former, already outdated, to standards of communication and specifications.

New attack uses vulnerability in the LTE protocol. This standard will provide by the end of the year communication for 1,37 billion subscribers. For carrying out attack it is required to bring together system from elements which total cost makes about $1400. As software Open Source software is used. The system, the NodeB node, allows to define location of phones compatible to the LTE standard, with an accuracy of 10-20 meters. In certain cases this equipment allows to learn also GPS coordinates of devices though attack of this kind can be found by the user of the smartphone. Also one more method of determination of coordinates of smartphones is developed, at the same time attack cannot almost be found. This method allows to define location of the set device within couple of square kilometers.

Read more »


Immersion cooling comes to new heights: 250 kW on a rack from BitFury

2 years ago


The BitFury company brings cooling with immersion to a new round of development: the manual declared intention to construct a new farm for a mining of cryptocurrency which power will make about 40 MW. At the same time about 250 kW will fall on one rack. For achievement of the specified purposes of BitFury is going to use the equipment from 3M.

The new object will be the world's largest where immersion cooling is used. A main objective — increase in density of placement of the equipment. The farm will be optimized for work with technology of submersible cooling, there will be no many elements of infrastructure characteristic of traditional data-centers. The very high density of placement of the equipment and high performance of work of this equipment — are critical for kriptomayningovy farms.

Trying to find new methods of increase of overall performance of the equipment, the BitFury company purchased Allied Control specializing in two-phase immersion cooling (2PIC) with use of coolant from 3M.

Read more »


As we looked for a bug in search Balansere, and found in Chromium

2 years ago
Some time ago colleagues began to receive from users complaints that sometimes when using Search and Yandex. The browser they see the error SSL connection error. Investigation of why it occurred, in my opinion, turned out interesting therefore I want to share it with you. In the course of analysis of a situation we several times changed the "suspected" software, studied a set of dump, remembered the device of the machine of statuses of TLS and as a result even understood Hromium's code. I hope, it will be interesting to you to read it not less, than to us was to investigate. So.



After a while we had records of logs of errors and pcap-files with similar contents:



All look like the server answered incorrectly and the client stopped handshake. Having analyzed "correct" (accepted by the client) and "incorrect" answers of the server, we understood that they are identical.

Read more »


Stekirovaniye of Cisco switches. Part 2

2 years ago

I welcome all!
In the first part of this article we considered rather old technologies of a stekirovaniye for family of Cisco switches 3750, namely StackWise and StackWise Plus. Today I suggest to continue consideration of other technologies. I will remind, we had StackWise-160, StackWise-480, FlexStack and FlexStack Plus.

Read more »


MikroTik — MTCNA

2 years ago
The Latvian company making the equipment under the MikroTik brand in recent years forced to fall in love with the equipment and in particular the RouterOS operating system. Times go, the company grows and develops, and every year expands the range including in the direction of sector Enterprise. Of course, to such giants as Cisco, Juniper, HP to it is still far, but MikroTik enters masses in our country more and more actively, and now "where spit", surely somewhere yes costs MikroTik.

The company won to itself love, for two reasons — the democratic price and functionality. Selection process of the equipment is reduced to the choice of a hardware component, and for all the rest there is RouterOS with huge functionality. It is natural how the good and proved vendor of network equipment, MikroTik has own system of certification of engineers and IT of specialists.

There are several levels of trainings:

1 level – initial basic.
  • MTCNA — MikroTik Certified Network Associate

2 level – engineering certificates in the directions.
  • MTCRE — MikroTik Certified Routing Engineer
  • MTCWE — MikroTik Certified Wireless Engineer
  • MTCTCE — MikroTik Certified Traffic Control Engineer
  • MTCUME — MikroTik Certified User Management Engineer

3 level — the highest, will suit those who work with networks of an operator class, or similar.
  • MTCINE — MikroTik Certified Inter-networking Engineer


Today we will talk about initial certified training of MikroTik, namely about an introduction course of MTCNA.


Read more »


The MikroTik setup as the OVPN server with use of kliyensky certificates and the list of a response

2 years ago
Before me there was a task to configure MikroTik as the OVPN server with use of client certificates and a possibility of their response. On this subject of accurate How-To I did not find in the Internet therefore decided to invent the own bicycle. In this article I will describe the scheme of setup of this miracle which turned out and working for me.

Read more »