KVM Performance Limits for virtual CPU cores

When using open-source network simulators that use KVM as a virtualization tool, each node in the network simulation is actually a KVM virtual machine so the maximum supported number of nodes in a network simulation is the same as the maximum number of KVM virtual machines that can run on the host computer.

Unfortunately, there seems to be no single authoritative statement about the maximum number of KVM virtual machines that can run on a host computer. Most information I could find about KVM limits does not publish absolute limits but, instead, recommends best practices.

In this post, I will synthesize the information available from many different sources into a single recommendation for the maximum number of KVM-based nodes that can run in an open-source network simulator running on a single host computer.

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Collecting MAC and IP Adresses of Hosts Connected to Cisco Switches Using SNMP

The goal of this article is to introduce a script that automates a process of collecting MAC and IP address of hosts connected to Cisco switches using Simple Network Management Protocol (SNMP). We will configure SNMP version 2c and 3 on Cisco switches and create a BASH script that collects required data for us. For this purpose I have created a test network lab using GNS3. The topology consists of three Cisco virtual switch appliances running vIOS-L2 and one network management station (NMS) based on Kali Linux. Network hosts are simulated by Core Linux appliances connected to Cisco vIOS-l2 switches.

1. GNS3 Lab

1.1 List of software used for creating GNS3 lab

  • Host OS
    x86-64 Linux Fedora with installed GNS3 1.3.11 and Qemu1.4.0
  • Network Management Station
    Linux Kali 3.18.0-kali3-amd64
  • Swiches
    Cisco vIOS l2 Software (vios_l2-ADVENTERPRISEK9-M), Version 15.2
    Cisco Catalyst 3550 (C3550-IPSERVICESK9-M), Version 12.2(55)SE9
  • Network Host (End device)
    Linux Core 3.16.6-tinycore64

1.2 Network Topology Description

All virtual network and host devices are running inside GNS3 project and they are emulated by Qemu emulator and virtualizer. The only exception is a Cisco Catalyst 3550 switch that is connected to topology via GNS3 network Continue reading

Walmart hired Lockheed Martin for employee surveillance, allegedly got help from FBI

It’s not unusual for companies to monitor social media in order to ‘protect’ their brands; Microsoft, for example, makes dossiers on journalists who write about the company. Yet Walmart allegedly “is always watching” and went the extra distance to spy on employees by hiring defense contractor Lockheed Martin and allegedly even received help from the FBI.Walmart was most interested in gathering surveillance of employees involved with the group OUR Walmart which planned Black Friday protests in 2012. OUR Walmart was advocating for higher wages, predictable schedules, better healthcare coverage, and the right to unionize. Walmart’s surveillance efforts were described in over 1,000 pages of “emails, reports, playbooks, charts, and graphs as well as testimony,” according to Bloomberg Businessweek which reviewed the documents. The testimony, which was given earlier this year to the National Labor Relations Board, claims Walmart hired Lockheed Martin and received help from the FBI Joint Terrorism Task Force.To read this article in full or to leave a comment, please click here

How I made my custom keyboard layout on Linux and Windows

This post explains how to set up a keyboard layout the way I like it. It may not fit you at all, but it may give you ideas that would work for you.

In short: I remap Caps Lock to add some extra keys.

First a description of what my preferred keyboard layout is: I type Dvorak, but also want to occasionally use Swedish letters. There are a couple of Dvorak versions for Swedish, but since most of my typing is in English or programming I think they compromise too much on the accessibility of other keys to add these three Swedish characters.

Picture of my keyboard

So for decade or so I’ve been remapping Caps Lock to AltGr and holding down AltGr to add new keys. Typing “ö” quickly became fluent and easy, since it involves holding down one key with my left hand and pressing a key with another.

I used this method even before I switched to Dvorak, because if you’ve ever coded on a Swedish keyboard you should know how terrible it is. I know several Swedish programmers who use US keyboard layout all the time because of this, and simply live without being able to type proper Swedish.

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How I made my custom keyboard layout on Linux and Windows

This post explains how to set up a keyboard layout the way I like it. It may not fit you at all, but it may give you ideas that would work for you.

In short: I remap Caps Lock to add some extra keys.

First a description of what my preferred keyboard layout is: I type Dvorak, but also want to occasionally use Swedish letters. There are a couple of Dvorak versions for Swedish, but since most of my typing is in English or programming I think they compromise too much on the accessibility of other keys to add these three Swedish characters.

Picture of my keyboard

So for decade or so I’ve been remapping Caps Lock to AltGr and holding down AltGr to add new keys. Typing “ö” quickly became fluent and easy, since it involves holding down one key with my left hand and pressing a key with another.

I used this method even before I switched to Dvorak, because if you’ve ever coded on a Swedish keyboard you should know how terrible it is. I know several Swedish programmers who use US keyboard layout all the time because of this, and simply live without being able to type proper Swedish.

Continue reading

Building pov-ray on raspberry pi

This is just notes in case I need to do this again. It’s for my QPov project.

sudo apt-get install autoconf libboost-all-dev libjpeg-dev libtiff-dev libpng-dev
git clone https://github.com/POV-Ray/povray.git
cd povray
git checkout --track -b 3.7-stable origin/3.7-stable
cd unix
./prebuild.sh
cd ..
./configure --prefix=$HOME/opt/povray COMPILED_BY="My_Name on RPi"
make
make install

Building pov-ray on raspberry pi

This is just notes in case I need to do this again. It’s for my QPov project.

sudo apt-get install autoconf libboost-all-dev libjpeg-dev libtiff-dev libpng-dev
git clone https://github.com/POV-Ray/povray.git
cd povray
git checkout --track -b 3.7-stable origin/3.7-stable
cd unix
./prebuild.sh
cd ..
./configure --prefix=$HOME/opt/povray COMPILED_BY="My_Name on RPi"
make
make install

Black Friday, Technology Glitches and Revenue Lost

This morning my wife was trying to purchase something from BELK.com. She ran into an issue at the point of transaction. The error that was being returned looked like the credit card number was invalid. Since the first attempt was on a mobile device, she attempted the transaction again from a computer. This was met with the same challenge. Ultimately, three different credit cards were attempted and none seemed to work. After reviewing the card account activity, I could see a total of about 5 authorizations against the 3 cards.

My wife contacted BELK by phone and they asked us to call our cc company (which I begrudgingly did). Finally they were able to process the cart transaction manually and admitted that we weren’t the only people experiencing the problem. They went on to say that their systems were very slow and that they were having issues with transactions internally too.
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Stuff The Internet Says On Scalability For November 27th, 2015

Hey, it's HighScalability time:


The most detailed picture of the Internet ever as compiled by an illegal 420,000-node botnet.
  • $40 billion: P2P lending in China; 20%: amount of all US margin expansion accounted for by Apple since 2010; 11: years of Saturn photos; 117: number of different steering wheels offered for a VW Golf; 1Gbps: speed of a network using a lightbulb.

  • Quotable Quotes:
    • @jaksprats: If we could compile a subset of JavaScript to Lua, JS could run on Server(Node,js), Browser, Desktop, iOS, & Android.JS could run EVERYWHERE
    • @wilkieii: Tech: "Don't roll your own crypto if you aren't an expert" *replaces nutrition with Soylent, currency with bitcoin* *puts wifi in lightbulb*
    • @brianpeddle: The architecture of one human brain would require a zettabyte of capacity. Full simulation of a human brain by 2023.
    • MarshalBanana: That can still easily be the right choice. Complex algorithms trade asymptotic performance for setup cost and maintenance cost. Sometimes the tradeoff isn't worth it.
    • kevindeasi: There are so many things to know nowadays. Backend: Sql, NoSql, NewSql, etc. Middlware: Django, NodeJs, Spring, Groovy, RoR, Symfony, etc. Client: Angular, Ember, React, Jquery, etc. I haven't even mentioned hardware, security, Continue reading

Microsoft enables potential unwanted software detection for enterprise customers

It’s time to throw adware, browser hijackers and other potentially unwanted applications (PUAs) off corporate networks, Microsoft has decided. The company has started offering PUA protection in its anti-malware products for enterprise customers.The new feature is available in Microsoft's System Center Endpoint Protection (SCEP) and Forefront Endpoint Protection (FEP) as an option that can be turned on by system administrators.PUA signatures are included in the anti-malware definition updates and cloud protection, so no additional configuration is needed.Potentially unwanted applications are those programs that, once installed, also deploy other programs without users' knowledge, inject advertisements into Web traffic locally, hijack browser search settings, or solicit payment for various services based on false claims.To read this article in full or to leave a comment, please click here

Kalinin nuclear power plant’s new neighbor will be a data center

Kalinin nuclear power plant's new neighbor will be a data center.The plant, near the city of Tver, is close to fiber-optic lines between Moscow and St Petersburg, providing the future data center with the double advantage of reliable power and fast communications links.When completed, the data center will be the largest in Russia, with a capacity of up to 10,000 racks, the company claims.Construction work will begin shortly, plant director Mikhail Kanyshev said Monday. The first phase is due to enter service in March 2017, and the second a year later, he said.Nuclear reactors need to run continuously, and so are a good match for loads that, like many data centers, run 24 hours a day. RosEnergoAtom expects the Kalinin data center to consume about 80 megawatts. That's just 2 percent of the neighboring power plant's generating capacity: Its four reactors are rated at 1 gigawatt each.To read this article in full or to leave a comment, please click here

Fibbing: OSPF-Based Traffic Engineering with Laurent Vanbever

You might be familiar with the idea of using BGP as an SDN tool that pushes forwarding entries into routing and forwarding tables of individual devices, allowing you to build hop-by-hop path across the network (more details in Packet Pushers podcast with Petr Lapukhov).

Researchers from University of Louvain, ETH Zürich and Princeton figured out how to use OSPF to get the same job done and called their approach Fibbing. For more details, listen to Episode 45 of Software Gone Wild podcast with Laurent Vanbever (one of the authors), visit the project web site, or download the source code.

Listen to the podcast

Network Simulation – Cisco Releases VIRL 1.0

Just in time for thanksgiving, Cisco has released version 1.0 of the popular network simulation tool VIRL. This is a major new release moving from Openstack Icehouse to Openstack Kilo. This means that your previous release of VIRL will NOT be upgradeable, only a fresh install is available. Cisco has started mailing out a link to the new release and I received my download link yesterday. It is also possible to download the image from the Salt server to the VM itself and then SCP it out from the VM, this is described in the release notes here.

The following platform reference VMs are included in this release:

  • IOSv – 15.5(3)M image
  • IOSvL2 – 15.2.4055 DSGS image
  • IOSXRv – 5.3.2 image
  • CSR1000v – 3.16 XE-based image
  • NX-OSv 7.2.0.D1.1(121)
  • ASAv 9.5.1
  • Ubuntu 14.4.2 Cloud-init

There are also Linux container images included. These are the following:

  • Ubuntu 14.4.2 LXC
  • iPerf LXC
  • Routem LXC
  • Ostinato LXC

This means that it will be a lot easier to do traffic generation, bandwidth testing and simulating a WAN by inserting delay, packet loss and jitter. It’s great to see Continue reading

Microsoft zaps dodgy Dell digital certificates

Microsoft has updated several of its security tools to remove two digital certificates installed on some Dell computers that could compromise data. The updates apply to Windows Defender for Windows 10 and 8.1; Microsoft Security Essentials for Windows 7 and Vista; and its Safety Scanner and Malicious Software Removal tool, according to postings here and here.To read this article in full or to leave a comment, please click here

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