Spanning The Tree : Dr Radia Perlman & Untangling Networks

As computer networks get bigger, it becomes increasingly hard to keep track of the flow of data over this network. How do you route data, making sure that the data is spread to all parts of the network? You use an algorithm called the spanning tree protocol — just one of the contributions to computer science of a remarkable engineer, Dr. Radia Perlman. But before she created this fundamental Internet protocol, she also worked on LOGO, the first programming language for children, creating a dialect for toddlers.

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Becoming Your Own ISP, Just for Fun

When moving into a new house, it’s important to arrange for the connection of basic utilities. Electricity, water, and gas are simple enough, and then it’s generally fairly easy to set up a connection to an ISP for your internet connection. A router plugs into a phone line, or maybe a fiber connection and lovely packets start flowing out of the wall. But if you’re connected to the internet through an ISP, how is the ISP connected? [Kenneth] answers this in the form of an amusing tale.

It was during the purchase of data centre rack space that [Kenneth]’s challenge was laid down by a friend. Rather then simply rely on the connection provided by the data centre, they would instead rely on forging their own connection to the ‘net, essentially becoming their own Internet Service Provider.

This is known as creating an Autonomous System. To do this involves several challenges, the first of which is understanding just how things work at this level of networking. [Kenneth] explains the vagaries of the Border Gateway Protocol, and why its neccessary to secure your own address space. There’s also an amusing discussion on the routing hardware required for such a feat and why [Kenneth]’s setup may fall over within the next two years or so.

It’s not for the faint hearted, and takes a fair bit of paperwork, but [Kenneth] has provided an excellent guide to the process if you really, really just need to own your own corner of the internet. That said, there are other networking tricks to cut your teeth on if you’d like a simpler challenge, like tunneling IP over ICMP.

 

Untether from Your Location With A VPN

By now, most of us know the perks of using a VPN: they make private one’s online activity (at least from your ISP’s point of view, probably), and they can also make it appear as if you are in a different locale than you physically are. This is especially important for trying to watch events such as the Olympics which might air different things at different times in different countries. It’s also starting to be an issue with services like Netflix which allow content in some areas but not others.

While VPNs can help solve this problem, it can be tedious to set them up for specific purposes like this if you have to do it often. Luckily, [clashtherage] has created a router with a Raspberry Pi that takes care of all of the complicated VPN routing automatically. In much the same way that another RPi router we’ve seen eliminates ads from all of your internet traffic, this one takes all of your traffic and sends it to a locale of your choosing. (In theory one could use both at the same time.)

Obviously this creates issues for Netflix as a company, and indeed a number of services (like craigslist, for example) are starting to block access to their sites if they detect that a VPN is being used. Of course, this only leads to an arms race of VPNs being blocked, and them finding ways around the obstacles, and on and on. If only IPv6 was finally implemented, we might have a solution for all of these issues.

Long Range Wireless Internet

While most of you reading this have broadband in your home, there are still vast areas with little access to the Internet. Ham radio operator [emmynet] found himself in just such a situation recently, and needed to get a wireless connection over 1 km from his home. WiFi wouldn’t get the job done, so he turned to a 433 MHz serial link instead. (Alternate link)

[emmynet] used an inexpensive telemetry kit that operates in a frequency that travels long distances much more easily than WiFi can travel. The key here isn’t in the hardware, however, but in the software. He went old-school, implemending peer-to-peer TCP/IP connection using SLIP — serial line Internet protocol. All of the commands to set up the link are available on his project page. With higher gain antennas than came with the telemetry kit, a range much greater than 1 km could be achieved as well.

[Editor’s note: This is how we all got Internet, over phone lines, back in the early Nineties. Also, you kids get off my lawn! But also, seriously, SLIP is a good tool to have in your toolbox, especially for low-power devices where WiFi would burn up your batteries.]

While it didn’t suit [emmynet]’s needs, it is possible to achieve extremely long range with WiFi itself. However this generally requires directional antennas with very high gain and might not be as reliable as a lower-frequency connection. On the other hand, a WiFi link will (in theory) get a greater throughput, so it all depends on what your needs are. Also, be aware that using these frequencies outside of their intended use might require an amateur radio license.

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This Quick Hack Will Keep You Online During Your Next Power Outage

The modern human’s worst nightmare: a power outage. Left without cat memes, Netflix, and — of course — Hackaday, there’s little to do except participate in the temporary anarchy that occurs when left without internet access. Lamenting over expensive and bulky uninterruptible power supplies, Youtube user [Gadget Addict] hacked together a UPS power bank that might just stave off the collapse of order in your household.

This simple and functional hack really amounts to snipping the end off of a USB  power cable. The cable is then attached to a screw terminal to barrel connector adapter and plugged it into a pass-through power USB power bank. No, really — that’s all there is to it. [Gadget Addict] notes that while most modems and routers are designed to run off a 12V power supply, they still operate at 5V. He goes on to connect several router and router/modem combination units to the power bank. In each case the system appears to boot up and perform normally.

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K.I.S.S. Pi Sprinkler – Just Keep the Plants Alive

A good first step in a project is knowing what you want to do. [Ben Fino] made it clear that his Raspberry Pi Sprinkler control system for his wife’s garden had one goal: keep the plants alive. The resulting project is doing just that and no more.

The circuitry, and plumbing, is straightforward and explained well in the Instructable. All the electronics consists of is the Pi and a MOSFET to take the 3.3v GPIO to 5v to control a relay. The valve controlling the water requires 28v AC which necessitated the relay to control it. There are also three LEDs: one is for power, one to indicate when the valve is opened, and one is an extra for some future purpose.

The intriguing part is the use of weather data from the web to determine if it’s rained recently. Python scripts provided by [Ben’s] friend [Mark Veillette] use a weather site API to get the rainfall data. The main script is set to run once every 24 hours. [Ben] set his system to water unless the previous day had sufficient rain. How much rain and the number of look-back days is programmable.

What a great application of the KISS principle: keep it simple, stupid – except for that third LED without a purpose.

The Long and Bumpy Road to Internet in Serbia

Internet is taken for granted. These days you assume there is Internet and only wonder if there is free WiFi to get onto it. But in the early days, connecting to a network could be tough and this was particularly true in Serbia. The country’s Internet revolution was complicated by both technology and politics, but the vibrance of the tech community always found a way.

The story is a fascinating one shared by Dejan Ristanovic at the Hackaday | Belgrade conference. He is now the Editor-in-Chief of PC Press computer magazine and played an integral part in providing global email access to Serbia. Enjoy the video of his talk below and join me after the break for a few highlights.

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