IP subnetting made easy George Ou explains IP subnetting using his own graphical approach. It's a great primer for students and a nice refresher for others. IP subnetting is a fundamental subject that's critical for any IP network engineer to understand, yet students have traditionally had a difficult time grasping it. IP addresses and subnets Although IP stands for Internet Protocol, it's a communications protocol used from the smallest private network to the massive global Internet. ...increment 252 hosts... ...increment 4+ billion hosts... The word subnet is short for sub network--a smaller network within a larger one. Subnets have a beginning and an ending, and the beginning number is always even and the ending number is always odd. The graphical subnet ruler Over the years, as I watched people struggle with the subject of IP subnetting, I wanted a better way to teach the subject. Note that for every bit increase, the size of the subnet doubles in length, along with the number of hosts. IP classes made simple
untitled Page d'accueil NIS (Network Information System) est un service qui permet la centralisation de tous les utilisateurs d'un réseau Unix ou Linux, sur un serveur.Grâce à NIS, on peut créer une bonne fois pour toutes, tous les utilisateurs d'un réseau, sur le seul serveur. On peut ensuite se connecter à l'un des comptes ainsi créés, à partir de n'importe quel poste client, et retrouver son environnement de travail (bureau, messagerie, paramètres personnels...). Pour disposer en même temps du partage d'informations et du partage de fichiers, il faut déployer à la fois NIS et NFS ; et pour davantage de performances et de souplesse, on utilisera aussi l'automonteur autofs. Ce tutoriel a été écrit pour une distribution MandrivaLinux LE 2005 mais il devrait être transposable sur d'autres systèmes GNU/Linux ou même Unix. a) Création des maps et installation du serveur maître : b) configuration du fichier /etc/nsswitch.conf sur les postes clients: Partage des dossiers utilisateurs: Conclusion :
Baking Pi - Operating Systems Development This course has not yet been updated to work with the Raspberry Pi models B+ and A+. Some elements may not work, in particular the first few lessons about the LED. It has also not been updated for Raspberry Pi v2. Welcome to Baking Pi: Operating Systems Development! Course by Alex Chadwick. You can now help contribute to this tutorial on GitHub. This website is here to guide you through the process of developing very basic operating systems on the Raspberry Pi! This course takes you through the basics of operating systems development in assembly code. Rather than leading the reader through the full details of creating an Operating System, these tutorials focus on achieving a few common tasks separately. 1 Requirements 1.1 Hardware In order to complete this course you will need a Raspberry Pi with an SD card and power supply. 1.2 Software In terms of software, you require a GNU compiler toolchain that targets ARMv6 processors. 2 Lessons
What Every Programmer Absolutely, Positively Needs to Know About Encodings and Character Sets to Work With Text If you are dealing with text in a computer, you need to know about encodings. Period. Yes, even if you are just sending emails. Even if you are just receiving emails. You don't need to understand every last detail, but you must at least know what this whole "encoding" thing is about. This article is about encodings and character sets. Getting the basics straight Everybody is aware of this at some level, but somehow this knowledge seems to suddenly disappear in a discussion about text, so let's get it out first: A computer cannot store "letters", "numbers", "pictures" or anything else. To use bits to represent anything at all besides bits, we need rules. 01100010 01101001 01110100 01110011 b i t s In this encoding, 01100010 stands for the letter "b", 01101001 for the letter "i", 01110100 stands for "t" and 01110011 for "s". The above encoding scheme happens to be ASCII. And there you have it, the way to represent human-readable text using only 1s and 0s. Important terms code page string Aha!
57 Simple Sys Admin Mistakes that Someday You’ll Regret When it comes to IT, simple mistakes can cost you big time. Whether that is immediately or not depends on a number of factors, and sometimes, when something has gone incredibly wrong, you won’t even realize that the root cause was a snap decision or simple oversight you made months ago. If you parse this list, you might just avoid a costly mistake sometime in the future; or, you may see something that makes you realize you weren’t the only one who had that happen. Networking There are tons of simple mistakes, oversights, omissions, and bad ideas that can bite you in the networking realm. Here are some of our favourites. 1. 2. 3. 4. 5. 6. 7. Other networking issues 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. User accounts and passwords 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. Speaking of Email… 31. 32. 33. 34. 35. 36. Active Directory 37. 38. 39. 40. Antivirus 41. 42. 43. Teach your Users well 44. 45. Other 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57.
What Is a Packet Sniffer? (with pictures) A packet sniffer is a device or program that allows the user to eavesdrop on traffic traveling between networked computers. The program will capture data that is addressed to other machines, saving it for later analysis. All information that travels across a network is sent in "packets." For example, when an email is sent from one computer to another, it is first broken up into smaller segments. In the example of the simplest network where computers share an Ethernet wire, all packets that travel between the computers are "seen" by every computer on the network. A slightly safer environment is a switched Ethernet network. There are ways to hack the switch protocol, however. These programs can also be used on the Internet to capture data traveling between computers. A packet sniffer is not just a hacker's tool. The best defense against eavesdropping is a good offense: encryption.
Unité réseaux du CNRS Actualités 1er avril 2014 Présentation de Docker, outil de gestion de conteneur LXC sous Linux. Lire l’article sur Docker 19 mars 2014 Article présentent l’utilisation de fichiers de propriétés en Groovy, ainsi que l’utilisation de l’annotation @ListenerList pour avoir facilement un bus d’événement à moindre coût. Lire l’article sur Groovy, les propriétés et @ListenerList 11 février 2014 Documentation d’installation du logiciel de messagerie instantanée Prosody et son intégration dans la fédération. Lire l’article Prosody 16 janvier 2014 Documentation d’installation de Proxmox 3.1 HA avec 2 nœuds. Lire l’article Proxmox 20 septembre 2013 Une fiche ressource sur Plume à propos des outils de monitoring en Java. Lire la fiche ressource 3 septembre 2013 Documentation d’installation de Smokeping 2.6. Lire l’article Smokeping 29 août 2013 Documentation d’installation du logiciel OpenVPN. Lire l’article OpenVPN 20 juin 2013 Lire l’article OwnCloud5 | Lire l’article SP Shibboleth 11 février 2013 Lire l’article
45 Free Online Computer Science Courses Missed lectures or hate teachers? Or want to study computer science courses without going to university? … You can study anytime anywhere because there are number of free online computer science courses available on internet that are very interactive. Here is the list of 45 free online computer science courses that are designed by teaching experts from best universities of the world (almost the whole graduation!). 1. Complete set of course materials. 2. This course is the natural successor to Programming Methodology and covers such advanced programming topics as recursion, algorithmic analysis, and data abstraction using the C++ programming language, which is similar to both C and Java. 3. Advanced memory management features of C and C++; the differences between imperative and object-oriented paradigms. 4. The purpose of this course is to introduce you to basics of modeling, design, planning, and control of robot systems. 5. 6. 7. 8. 9. 10. Continuation of Convex Optimization I. 11. 12.
The AIRHAWK A5 Mobile (Pocket) Hard Drives - with 2x FireWire 400 and USB Ports The AIRHAWK A5 Mobile (Pocket) Hard Drives - with 2x FireWire 400 and USB Ports The AIRHAWK pocket drives deliver exceptional performance and reliability. Designed and engineered to meet the needs of a demanding mobile data storage market, the AIRHAWK 2.5” external hard drives are compatible with both Windows® and Macintosh® environments. AIRHAWK A5 - “These drives are both bus-powered and bootable.” The new AIRHAWK pocket drives contain a fast, high capacity 2.5” SATA drive mechanism, with up to 480 Mbit/sec transfer speed and multiple interfaces in a stylish case for thermal efficiency and silent operation. Groundbreaking Design The first design of its kind, the AIRHAWK sets a new standard for unprecedented design, quality, versatility and capability that will satisfy the most sophisticated audience. Despite its diminutive size and shock-absorbent chamber, the AIRHAWK’s wide array of ports ensures maximum compatibility regardless of the type of computer or operating system in use.
Bluesnarfing Bluesnarfing is the unauthorized access of information from a wireless device through a Bluetooth connection, often between phones, desktops, laptops, and PDAs (personal digital assistant.). This allows access to a calendar, contact list, emails and text messages, and on some phones, users can copy pictures and private videos. Both Bluesnarfing and Bluejacking exploit others' Bluetooth connections without their knowledge. While Bluejacking is essentially harmless as it only transmits data to the target device, Bluesnarfing is the theft of information from the target device. Current mobile software generally must allow a connection using a temporary state initiated by the user in order to be 'paired' with another device to copy content. Any device with its Bluetooth connection turned on and set to "discoverable" (able to be found by other Bluetooth devices in range) may be susceptible to Bluejacking and possibly to Bluesnarfing if there is a vulnerability in the vendor's software.