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  • How to Run Low-Cost Minecraft on a Raspberry Pi for Block Building on the Cheap

    - by Jason Fitzpatrick
    We’ve shown you how to run your own blocktastic personal Minecraft server on a Windows/OSX box, but what if you crave something lighter weight, more energy efficient, and always ready for your friends? Read on as we turn a tiny Raspberry Pi machine into a low-cost Minecraft server you can leave on 24/7 for around a penny a day. Why Do I Want to Do This? There’s two aspects to this tutorial, running your own Minecraft server and specifically running that Minecraft server on a Raspberry Pi. Why would you want to run your own Minecraft server? It’s a really great way to extend and build upon the Minecraft play experience. You can leave the server running when you’re not playing so friends and family can join and continue building your world. You can mess around with game variables and introduce mods in a way that isn’t possible when you’re playing the stand-alone game. It also gives you the kind of control over your multiplayer experience that using public servers doesn’t, without incurring the cost of hosting a private server on a remote host. While running a Minecraft server on its own is appealing enough to a dedicated Minecraft fan, running it on the Raspberry Pi is even more appealing. The tiny little Pi uses so little resources that you can leave your Minecraft server running 24/7 for a couple bucks a year. Aside from the initial cost outlay of the Pi, an SD card, and a little bit of time setting it up, you’ll have an always-on Minecraft server at a monthly cost of around one gumball. What Do I Need? For this tutorial you’ll need a mix of hardware and software tools; aside from the actual Raspberry Pi and SD card, everything is free. 1 Raspberry Pi (preferably a 512MB model) 1 4GB+ SD card This tutorial assumes that you have already familiarized yourself with the Raspberry Pi and have installed a copy of the Debian-derivative Raspbian on the device. If you have not got your Pi up and running yet, don’t worry! Check out our guide, The HTG Guide to Getting Started with Raspberry Pi, to get up to speed. Optimizing Raspbian for the Minecraft Server Unlike other builds we’ve shared where you can layer multiple projects over one another (e.g. the Pi is more than powerful enough to serve as a weather/email indicator and a Google Cloud Print server at the same time) running a Minecraft server is a pretty intense operation for the little Pi and we’d strongly recommend dedicating the entire Pi to the process. Minecraft seems like a simple game, with all its blocky-ness and what not, but it’s actually a pretty complex game beneath the simple skin and required a lot of processing power. As such, we’re going to tweak the configuration file and other settings to optimize Rasbian for the job. The first thing you’ll need to do is dig into the Raspi-Config application to make a few minor changes. If you’re installing Raspbian fresh, wait for the last step (which is the Raspi-Config), if you already installed it, head to the terminal and type in “sudo raspi-config” to launch it again. One of the first and most important things we need to attend to is cranking up the overclock setting. We need all the power we can get to make our Minecraft experience enjoyable. In Raspi-Config, select option number 7 “Overclock”. Be prepared for some stern warnings about overclocking, but rest easy knowing that overclocking is directly supported by the Raspberry Pi foundation and has been included in the configuration options since late 2012. Once you’re in the actual selection screen, select “Turbo 1000MhHz”. Again, you’ll be warned that the degree of overclocking you’ve selected carries risks (specifically, potential corruption of the SD card, but no risk of actual hardware damage). Click OK and wait for the device to reset. Next, make sure you’re set to boot to the command prompt, not the desktop. Select number 3 “Enable Boot to Desktop/Scratch”  and make sure “Console Text console” is selected. Back at the Raspi-Config menu, select number 8 “Advanced Options’. There are two critical changes we need to make in here and one option change. First, the critical changes. Select A3 “Memory Split”: Change the amount of memory available to the GPU to 16MB (down from the default 64MB). Our Minecraft server is going to ruin in a GUI-less environment; there’s no reason to allocate any more than the bare minimum to the GPU. After selecting the GPU memory, you’ll be returned to the main menu. Select “Advanced Options” again and then select A4 “SSH”. Within the sub-menu, enable SSH. There is very little reason to keep this Pi connected to a monitor and keyboard, by enabling SSH we can remotely access the machine from anywhere on the network. Finally (and optionally) return again to the “Advanced Options” menu and select A2 “Hostname”. Here you can change your hostname from “raspberrypi” to a more fitting Minecraft name. We opted for the highly creative hostname “minecraft”, but feel free to spice it up a bit with whatever you feel like: creepertown, minecraft4life, or miner-box are all great minecraft server names. That’s it for the Raspbian configuration tab down to the bottom of the main screen and select “Finish” to reboot. After rebooting you can now SSH into your terminal, or continue working from the keyboard hooked up to your Pi (we strongly recommend switching over to SSH as it allows you to easily cut and paste the commands). If you’ve never used SSH before, check out how to use PuTTY with your Pi here. Installing Java on the Pi The Minecraft server runs on Java, so the first thing we need to do on our freshly configured Pi is install it. Log into your Pi via SSH and then, at the command prompt, enter the following command to make a directory for the installation: sudo mkdir /java/ Now we need to download the newest version of Java. At the time of this publication the newest release is the OCT 2013 update and the link/filename we use will reflect that. Please check for a more current version of the Linux ARMv6/7 Java release on the Java download page and update the link/filename accordingly when following our instructions. At the command prompt, enter the following command: sudo wget --no-check-certificate http://www.java.net/download/jdk8/archive/b111/binaries/jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz Once the download has finished successfully, enter the following command: sudo tar zxvf jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz -C /opt/ Fun fact: the /opt/ directory name scheme is a remnant of early Unix design wherein the /opt/ directory was for “optional” software installed after the main operating system; it was the /Program Files/ of the Unix world. After the file has finished extracting, enter: sudo /opt/jdk1.8.0/bin/java -version This command will return the version number of your new Java installation like so: java version "1.8.0-ea" Java(TM) SE Runtime Environment (build 1.8.0-ea-b111) Java HotSpot(TM) Client VM (build 25.0-b53, mixed mode) If you don’t see the above printout (or a variation thereof if you’re using a newer version of Java), try to extract the archive again. If you do see the readout, enter the following command to tidy up after yourself: sudo rm jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz At this point Java is installed and we’re ready to move onto installing our Minecraft server! Installing and Configuring the Minecraft Server Now that we have a foundation for our Minecraft server, it’s time to install the part that matter. We’ll be using SpigotMC a lightweight and stable Minecraft server build that works wonderfully on the Pi. First, grab a copy of the the code with the following command: sudo wget http://ci.md-5.net/job/Spigot/lastSuccessfulBuild/artifact/Spigot-Server/target/spigot.jar This link should remain stable over time, as it points directly to the most current stable release of Spigot, but if you have any issues you can always reference the SpigotMC download page here. After the download finishes successfully, enter the following command: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Note: if you’re running the command on a 256MB Pi change the 256 and 496 in the above command to 128 and 256, respectively. Your server will launch and a flurry of on-screen activity will follow. Be prepared to wait around 3-6 minutes or so for the process of setting up the server and generating the map to finish. Future startups will take much less time, around 20-30 seconds. Note: If at any point during the configuration or play process things get really weird (e.g. your new Minecraft server freaks out and starts spawning you in the Nether and killing you instantly), use the “stop” command at the command prompt to gracefully shutdown the server and let you restart and troubleshoot it. After the process has finished, head over to the computer you normally play Minecraft on, fire it up, and click on Multiplayer. You should see your server: If your world doesn’t popup immediately during the network scan, hit the Add button and manually enter the address of your Pi. Once you connect to the server, you’ll see the status change in the server status window: According to the server, we’re in game. According to the actual Minecraft app, we’re also in game but it’s the middle of the night in survival mode: Boo! Spawning in the dead of night, weaponless and without shelter is no way to start things. No worries though, we need to do some more configuration; no time to sit around and get shot at by skeletons. Besides, if you try and play it without some configuration tweaks first, you’ll likely find it quite unstable. We’re just here to confirm the server is up, running, and accepting incoming connections. Once we’ve confirmed the server is running and connectable (albeit not very playable yet), it’s time to shut down the server. Via the server console, enter the command “stop” to shut everything down. When you’re returned to the command prompt, enter the following command: sudo nano server.properties When the configuration file opens up, make the following changes (or just cut and paste our config file minus the first two lines with the name and date stamp): #Minecraft server properties #Thu Oct 17 22:53:51 UTC 2013 generator-settings= #Default is true, toggle to false allow-nether=false level-name=world enable-query=false allow-flight=false server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true texture-pack= snooper-enabled=true hardcore=false online-mode=true pvp=true difficulty=1 player-idle-timeout=0 gamemode=0 #Default 20; you only need to lower this if you're running #a public server and worried about loads. max-players=20 spawn-monsters=true #Default is 10, 3-5 ideal for Pi view-distance=5 generate-structures=true spawn-protection=16 motd=A Minecraft Server In the server status window, seen through your SSH connection to the pi, enter the following command to give yourself operator status on your Minecraft server (so that you can use more powerful commands in game, without always returning to the server status window). op [your minecraft nickname] At this point things are looking better but we still have a little tweaking to do before the server is really enjoyable. To that end, let’s install some plugins. The first plugin, and the one you should install above all others, is NoSpawnChunks. To install the plugin, first visit the NoSpawnChunks webpage and grab the download link for the most current version. As of this writing the current release is v0.3. Back at the command prompt (the command prompt of your Pi, not the server console–if your server is still active shut it down) enter the following commands: cd /home/pi/plugins sudo wget http://dev.bukkit.org/media/files/586/974/NoSpawnChunks.jar Next, visit the ClearLag plugin page, and grab the latest link (as of this tutorial, it’s v2.6.0). Enter the following at the command prompt: sudo wget http://dev.bukkit.org/media/files/743/213/Clearlag.jar Because the files aren’t compressed in a .ZIP or similar container, that’s all there is to it: the plugins are parked in the plugin directory. (Remember this for future plugin downloads, the file needs to be whateverplugin.jar, so if it’s compressed you need to uncompress it in the plugin directory.) Resart the server: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Be prepared for a slightly longer startup time (closer to the 3-6 minutes and much longer than the 30 seconds you just experienced) as the plugins affect the world map and need a minute to massage everything. After the spawn process finishes, type the following at the server console: plugins This lists all the plugins currently active on the server. You should see something like this: If the plugins aren’t loaded, you may need to stop and restart the server. After confirming your plugins are loaded, go ahead and join the game. You should notice significantly snappier play. In addition, you’ll get occasional messages from the plugins indicating they are active, as seen below: At this point Java is installed, the server is installed, and we’ve tweaked our settings for for the Pi.  It’s time to start building with friends!     

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  • OpenVPN: ifup tap0 drops all connections

    - by raspi
    I'm trying to create star shaped "virtual" LAN with OpenVPN which is not connected to physical network. ie. tap0 packets should not go to eth0. Packet should only go through OpenVPN to connected clients. This setup works with my OpenVPN testing machine which runs Virtual Box but not on my actual server which is running on top of Xen. Both servers are running Ubuntu Intrepid. /etc/network/interfaces: iface tap0 inet manual address 10.10.10.1 netmask 255.255.255.0 gateway 10.10.10.1 /etc/openvpn/server.conf mode server tls-server port 1194 proto udp dev tap client-to-client ca /etc/openvpn/easy-rsa/keys/ca.crt cert /etc/openvpn/easy-rsa/keys/servername.crt key /etc/openvpn/easy-rsa/keys/servername.key dh /etc/openvpn/easy-rsa/keys/dh384.pem ifconfig-pool-persist ipp.txt server-bridge 10.10.10.1 255.255.255.0 10.10.10.128 10.10.10.250 push .route 10.10.10.1 255.255.255.0 keepalive 5 60 comp-lzo persist-key persist-tun status /var/log/openvpn-status.log log-append /var/log/openvpn.log verb 3 user nobody group nogroup ifup tap0 on Virtual Box: everything ok, SSH keeps running. But on Xen SSH connection drops and I have to reboot whole machine. What I'm missing?

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  • Linux VLAN Bridge

    - by raspi
    I have home network with VLANs, one for LAN, one for WLAN and one for internet. I'd like to use bridging so that instead of configuring these same VLANs to every machine, they had own VLAN ID and bridges were LAN, WLAN and internet. I've tried it but for some reason keep-alive/ttl seems to get broken because SSH sessions etc suddenly disconnects. We have this same setup working in workplace for 4+ years with 100+ customers but it's custom firewall/router hardware so accessing it is impossible. I know that it runs Linux. So what is Debian/Ubuntu default network settings doing wrong or is it just NIC driver/hw problem? I've tried to mess araund with ttl etc settings without any luck. The bad stuff is happening in the bridge because current VLAN-only setup works fine. interfaces: auto lo iface lo inet loopback # The primary network interface allow-hotplug eth0 allow-hotplug eth1 iface eth0 inet static iface eth1 inet static auto vlan111 auto vlan222 auto vlan333 auto vlan444 auto br0 auto br1 auto br2 # LAN iface vlan111 inet static vlan_raw_device eth0 # WLAN iface vlan222 inet static vlan_raw_device eth0 # ADSL Modem iface vlan333 inet static vlan_raw_device eth1 # Internet iface vlan444 inet static vlan_raw_device eth0 # LAN bridge iface br0 inet static address 192.168.0.1 netmask 255.255.255.0 bridge_ports eth0.111 bridge_stp on # Internet bridge iface br1 inet static address x.x.x.x netmask x.x.x.x gateway x.x.x.x bridge_ports eth1.333 eth0.444 bridge_stp on post-up iptables -t nat -A POSTROUTING -o br1 -j MASQUERADE pre-down iptables -t nat -D POSTROUTING -o br1 -j MASQUERADE # WLAN bridge iface br2 inet static address 192.168.1.1 netmask 255.255.255.0 bridge_ports eth0.222 bridge_stp on Sysctl: net.ipv4.conf.default.forwarding=1

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  • What you'd need to setup BBS?

    - by raspi
    What I need to setup BBS nowadays? I'm thinking of BBBS or PCBoard (no telnet! too new technology). What I've thinked so far, I'd need: virtual machine which runs DOS and hook that virtual COM-port to somekind of virtual VoIP modem software somehow (is there any?). How you can call to it across internet? Can you use HyperTerminal straight with that virtual/real modem? Or will VoIP just garble the modem data and nothing will work?

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  • Integrating NetBeans for Raspberry Pi Java Development

    - by speakjava
    Raspberry Pi IDE Java Development The Raspberry Pi is an incredible device for building embedded Java applications but, despite being able to run an IDE on the Pi it really pushes things to the limit.  It's much better to use a PC or laptop to develop the code and then deploy and test on the Pi.  What I thought I'd do in this blog entry was to run through the steps necessary to set up NetBeans on a PC for Java code development, with automatic deployment to the Raspberry Pi as part of the build process. I will assume that your starting point is a Raspberry Pi with an SD card that has one of the latest Raspbian images on it.  This is good because this now includes the JDK 7 as part of the distro, so no need to download and install a separate JDK.  I will also assume that you have installed the JDK and NetBeans on your PC.  These can be downloaded here. There are numerous approaches you can take to this including mounting the file system from the Raspberry Pi remotely on your development machine.  I tried this and I found that NetBeans got rather upset if the file system disappeared either through network interruption or the Raspberry Pi being turned off.  The following method uses copying over SSH, which will fail more gracefully if the Pi is not responding. Step 1: Enable SSH on the Raspberry Pi To run the Java applications you create you will need to start Java on the Raspberry Pi with the appropriate class name, classpath and parameters.  For non-JavaFX applications you can either do this from the Raspberry Pi desktop or, if you do not have a monitor connected through a remote command line.  To execute the remote command line you need to enable SSH (a secure shell login over the network) and connect using an application like PuTTY. You can enable SSH when you first boot the Raspberry Pi, as the raspi-config program runs automatically.  You can also run it at any time afterwards by running the command: sudo raspi-config This will bring up a menu of options.  Select '8 Advanced Options' and on the next screen select 'A$ SSH'.  Select 'Enable' and the task is complete. Step 2: Configure Raspberry Pi Networking By default, the Raspbian distribution configures the ethernet connection to use DHCP rather than a static IP address.  You can continue to use DHCP if you want, but to avoid having to potentially change settings whenever you reboot the Pi using a static IP address is simpler. To configure this on the Pi you need to edit the /etc/network/interfaces file.  You will need to do this as root using the sudo command, so something like sudo vi /etc/network/interfaces.  In this file you will see this line: iface eth0 inet dhcp This needs to be changed to the following: iface eth0 inet static     address 10.0.0.2     gateway 10.0.0.254     netmask 255.255.255.0 You will need to change the values in red to an appropriate IP address and to match the address of your gateway. Step 3: Create a Public-Private Key Pair On Your Development Machine How you do this will depend on which Operating system you are using: Mac OSX or Linux Run the command: ssh-keygen -t rsa Press ENTER/RETURN to accept the default destination for saving the key.  We do not need a passphrase so simply press ENTER/RETURN for an empty one and once more to confirm. The key will be created in the file .ssh/id_rsa.pub in your home directory.  Display the contents of this file using the cat command: cat ~/.ssh/id_rsa.pub Open a window, SSH to the Raspberry Pi and login.  Change directory to .ssh and edit the authorized_keys file (don't worry if the file does not exist).  Copy and paste the contents of the id_rsa.pub file to the authorized_keys file and save it. Windows Since Windows is not a UNIX derivative operating system it does not include the necessary key generating software by default.  To generate the key I used puttygen.exe which is available from the same site that provides the PuTTY application, here. Download this and run it on your Windows machine.  Follow the instructions to generate a key.  I remove the key comment, but you can leave that if you want. Click "Save private key", confirm that you don't want to use a passphrase and select a filename and location for the key. Copy the public key from the part of the window marked, "Public key for pasting into OpenSSH authorized_keys file".  Use PuTTY to connect to the Raspberry Pi and login.  Change directory to .ssh and edit the authorized_keys file (don't worry if this does not exist).  Paste the key information at the end of this file and save it. Logout and then start PuTTY again.  This time we need to create a saved session using the private key.  Type in the IP address of the Raspberry Pi in the "Hostname (or IP address)" field and expand "SSH" under the "Connection" category.  Select "Auth" (see the screen shot below). Click the "Browse" button under "Private key file for authentication" and select the file you saved from puttygen. Go back to the "Session" category and enter a short name in the saved sessions field, as shown below.  Click "Save" to save the session. Step 4: Test The Configuration You should now have the ability to use scp (Mac/Linux) or pscp.exe (Windows) to copy files from your development machine to the Raspberry Pi without needing to authenticate by typing in a password (so we can automate the process in NetBeans).  It's a good idea to test this using something like: scp /tmp/foo [email protected]:/tmp on Linux or Mac or pscp.exe foo pi@raspi:/tmp on Windows (Note that we use the saved configuration name instead of the IP address or hostname so the public key is picked up). pscp.exe is another tool available from the creators of PuTTY. Step 5: Configure the NetBeans Build Script Start NetBeans and create a new project (or open an existing one that you want to deploy automatically to the Raspberry Pi). Select the Files tab in the explorer window and expand your project.  You will see a build.xml file.  Double click this to edit it. This file will mostly be comments.  At the end (but within the </project> tag) add the XML for <target name="-post-jar">, shown below Here's the code again in case you want to use cut-and-paste: <target name="-post-jar">   <echo level="info" message="Copying dist directory to remote Pi"/>   <exec executable="scp" dir="${basedir}">     <arg line="-r"/>     <arg value="dist"/>     <arg value="[email protected]:NetBeans/CopyTest"/>   </exec>  </target> For Windows it will be slightly different: <target name="-post-jar">   <echo level="info" message="Copying dist directory to remote Pi"/>   <exec executable="C:\pi\putty\pscp.exe" dir="${basedir}">     <arg line="-r"/>     <arg value="dist"/>     <arg value="pi@raspi:NetBeans/CopyTest"/>   </exec> </target> You will also need to ensure that pscp.exe is in your PATH (or specify a fully qualified pathname). From now on when you clean and build the project the dist directory will automatically be copied to the Raspberry Pi ready for testing.

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  • Prepping the Raspberry Pi for Java Excellence (part 1)

    - by HecklerMark
    I've only recently been able to begin working seriously with my first Raspberry Pi, received months ago but hastily shelved in preparation for JavaOne. The Raspberry Pi and other diminutive computing platforms offer a glimpse of the potential of what is often referred to as the embedded space, the "Internet of Things" (IoT), or Machine to Machine (M2M) computing. I have a few different configurations I want to use for multiple Raspberry Pis, but for each of them, I'll need to perform the following common steps to prepare them for their various tasks: Load an OS onto an SD card Get the Pi connected to the network Load a JDK I've been very happy to see good friend and JFXtras teammate Gerrit Grunwald document how to do these things on his blog (link to article here - check it out!), but I ran into some issues configuring wi-fi that caused me some needless grief. Not knowing if any of the pitfalls were caused by my slightly-older version of the Pi and not being able to find anything specific online to help me get past it, I kept chipping away at it until I broke through. The purpose of this post is to (hopefully) help someone else recognize the same issues if/when they encounter them and work past them quickly. There is a great resource page here that covers several ways to get the OS on an SD card, but here is what I did (on a Mac): Plug SD card into reader on/in Mac Format it (FAT32) Unmount it (diskutil unmountDisk diskn, where n is the disk number representing the SD card) Transfer the disk image for Debian to the SD card (dd if=2012-08-08-wheezy-armel.img of=/dev/diskn bs=1m) Eject the card from the Mac (diskutil eject diskn) There are other ways, but this is fairly quick and painless, especially after you do it several times. Yes, I had to do that dance repeatedly (minus formatting) due to the wi-fi issues, as it kept killing the ability of the Pi to boot. You should be able to dramatically reduce the number of OS loads you do, though, if you do a few things with regard to your wi-fi. Firstly, I strongly recommend you purchase the Edimax EW-7811Un wi-fi adapter. This adapter/chipset has been proven with the Raspberry Pi, it's tiny, and it's cheap. Avoid unnecessary aggravation and buy this one! Secondly, visit this page for a script and instructions regarding how to configure your new wi-fi adapter with your Pi. Here is the rub, though: there is a missing step. At least for my combination of Pi version, OS version, and uncanny gift of timing and luck there was. :-) Here is the sequence of steps I used to make the magic happen: Plug your newly-minted SD card (with OS) into your Pi and connect a network cable (for internet connectivity) Boot your Pi. On the first boot, do the following things: Opt to have it use all space on the SD card (will require a reboot eventually) Disable overscan Set your timezone Enable the ssh server Update raspi-config Reboot your Pi. This will reconfigure the SD to use all space (see above). After you log in (UID: pi, password: raspberry), upgrade your OS. This was the missing step for me that put a merciful end to the repeated SD card re-imaging and made the wi-fi configuration trivial. To do so, just type sudo apt-get upgrade and give it several minutes to complete. Pour yourself a cup of coffee and congratulate yourself on the time you've just saved.  ;-) With the OS upgrade finished, now you can follow Mr. Engman's directions (to the letter, please see link above), download his script, and let it work its magic. One aside: I plugged the little power-sipping Edimax directly into the Pi and it worked perfectly. No powered hub needed, at least in my configuration. To recap, that OS upgrade (at least at this point, with this combination of OS/drivers/Pi version) is absolutely essential for a smooth experience. Miss that step, and you're in for hours of "fun". Save yourself! I'll pick up next time with more of the Java side of the RasPi configuration, but as they say, you have to cross the moat to get into the castle. Hopefully, this will help you do just that. Until next time! All the best, Mark 

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  • The Power to Control Power

    - by speakjava
    I'm currently working on a number of projects using embedded Java on the Raspberry Pi and Beagle Board.  These are nice and small, so don't take up much room on my desk as you can see in this picture. As you can also see I have power and network connections emerging from under my desk.  One of the (admittedly very minor) drawbacks of these systems is that they have no on/off switch.  Instead you insert or remove the power connector (USB for the RasPi, a barrel connector for the Beagle).  For the Beagle Board this can potentially be an issue; with the micro-SD card located right next to the connector it has been known for people to eject the card when trying to power off the board, which can be quite serious for the hardware. The alternative is obviously to leave the boards plugged in and then disconnect the power from the outlet.  Simple enough, but a picture of underneath my desk shows that this is not the ideal situation either. This made me think that it would be great if I could have some way of controlling a mains voltage outlet using a remote switch or, even better, from software via a USB connector.  A search revealed not much that fit my requirements, and anything that was close seemed very expensive.  Obviously the only way to solve this was to build my own.Here's my solution.  I decided my system would support both control mechanisms (remote physical switch and USB computer control) and be modular in its design for optimum flexibility.  I did a bit of searching and found a company in Hong Kong that were offering solid state relays for 99p plus shipping (£2.99, but still made the total price very reasonable).  These would handle up to 380V AC on the output side so more than capable of coping with the UK 240V supply.  The other great thing was that being solid state, the input would work with a range of 3-32V and required a very low current of 7.5mA at 12V.  For the USB control an Arduino board seemed the obvious low-cost and simple choice.  Given the current requirments of the relay, the Arduino would not require the additional power supply and could be powered just from the USB.Having secured the relays I popped down to Homebase for a couple of 13A sockets, RS for a box and an Arduino and Maplin for a toggle switch.  The circuit is pretty straightforward, as shown in the diagram (only one output is shown to make it as simple as possible).  Originally I used a 2 pole toggle switch to select the remote switch or USB control by switching the negative connections of the low voltage side.  Unfortunately, the resistance between the digital pins of the Arduino board was not high enough, so when using one of the remote switches it would turn on both of the outlets.  I changed to a 4 pole switch and isolated both positive and negative connections. IMPORTANT NOTE: If you want to follow my design, please be aware that it requires working with mains voltages.  If you are at all concerned with your ability to do this please consult a qualified electrician to help you.It was a tight fit, especially getting the Arduino in, but in the end it all worked.  The completed box is shown in the photos. The remote switch was pretty simple just requiring the squeezing of two rocker switches and a 9V battery into the small RS supplied box.  I repurposed a standard stereo cable with phono plugs to connect the switch box to the mains outlets.  I chopped off one set of plugs and wired it to the rocker switches.  The photo shows the RasPi and the Beagle board now controllable from the switch box on the desk. I've tested the Arduino side of things and this works fine.  Next I need to write some software to provide an interface for control of the outlets.  I'm thinking a JavaFX GUI would be in keeping with the total overkill style of this project.

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  • Can I autoregister my clients/servers in local DNS?

    - by Christian Wattengård
    Right now I have a W2k12 server at home that I run as a domain controller. This has the extra benefit of registering every "subordinate" computers name in it's DNS so that I don't have to go around remembering IP's all the time. (And it let's me easily run dhcp also on my servers). I need to rework my home network for several odd reasons, and in this new scenario there is no place for a big honking W2k12 server box. I have a RasPI, and I have other smallish linux boxen I can use. (In a worst case scenario I'll use my NUC, but then I'll be forced to use my home cinema's UPnP-client for media... The HORROR!!) Is it possible to set up a DNS-server-"appliance" that somehow autoregisters it's own hostname.. Scenario: Router (N66u) on 172.20.20.1. Runs DHCP on 172.20.20.100-200 range. Server [verdant] of a *nix flavor on 172.20.20.2 Laptop [speedy] of W8 flavor on DHCP assigned Laptop [canary] of W8 flavor on DHCP assigned Desktop [lianyu] of Ubunto flavor on DHCP assigned What I would like is that all of the above servers (except possibly the router) would be available on verdant.starling.lan and canary.starling.lan and so on. This is how it works right now (except the Ubuntu box... I haven't cracked that one yet) because Windows just does this for you.. I would also be able to do this without any manual labor on the server. When I tell my box it's name is smoak it should "immediately" be available as smoak.starling.lan without any extra configuration on my part. How can I do this in a Linux (Ubuntu) environment? (Bonus comment upvote for naming the naming scheme :P )

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  • Can only ssh when not using wifi

    - by AChrapko
    So I have 3 machines, a windows 7 desktop that is always wired to my router, osX laptop, and raspberry pi running debian linux. My router is a Linksys e1000 wireless N. My goal is to be able to ssh the raspi from any machine, while it is connected via wifi. My problem is that when trying to ssh from either the win7 or osX to the Pi it either times out, or gives an error: "ssh: connect to host 192.168.1.### port 22: No route to host" The only times that I have managed to connect to the pi from any machine were when it connected to the router via an Ethernet cable. Currently with win7 desktop wired, macbook wireless, and pi wireless tests give the following: win7 ping macbook: Destination host unreachable. macbook ping win7: Request timeout. win7 ping pi: Destination host unreachable. macbook ping pi: Request timeout. blah blah blah Plugging the macbook into the router with an Ethernet cable all communication between win7 and macbook works. Pings, ssh, ftp, smb ect... No changes to the pi, still no connections possible to or from any of the other 2 machines. Note All machines, are able to connect to the internet and ssh to the same machine on a completely different network, wired or over wifi. Plugging the Pi in with Ethernet (and macbook still wired) I can ssh to the pi from both win7 and macbook. I can ssh from the pi to macbook. All machines still able to connect the the off network machine. Also another little side note- I was playing warcraft 3 with my roommates the other day, and the only time they were able to see my LAN game was when they were plugged into the router with an Ethernet cable. Once or twice one of the laptops was able to connect over wifi, but not without another computer connecting first via Ethernet. So basically does anyone have any info as to why my router seems to completely ignore local wireless traffic?

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  • Wrapping a point-to-point link

    - by user3712955
    I'm using a pair of IP radios (non-WiFi) to bridge my office engineering LAN (172.0.0.0/8) to a lab in another building. The radios work fine, but they expose a web management interface I'd like to hide, and they also generate traffic (ARP, STP, and more) that I need to keep off my (very, very clean) LAN segments. I have some ARM-Linux boards (similar to Beagle/Panda/RasPi) running Ubuntu, and I've put one at each end of the link, between the radio and the LAN. Each of the boards has 2 wired Ethernet interfaces, eth0 and eth1. The LAN segments are connected to eth0, and the radios are connected to eth1. I'd like to accomplish the following: Keep radio-originated traffic off my LAN segments! Hide all services provided by the radio (web, ssh, etc.) Transparently pass all traffic between the LAN segments (including things like ARP). The above also applies to the ARM-Linux boards: No stray traffic my LAN from them either! I'd like the system to look like a switch: LAN packets arriving at one eth0 appear at the other. And neither eth0 should have an IP address: The working system should behave like a CAT6 cable with some latency (instead of ARM boards and radios). Unfortunately, I'm confused about how to properly configure the ARM Ubuntu systems. What I'm guessing I need is a bridge on each board (br0?) and a VLAN (vlan0 or eth0.0?) to isolate the LAN traffic from everything else as it passes through the ARM boards and the radios. Then I need some kind of a firewall to block sending anything out eth0 that isn't from the other eth0 (via the VLAN). I've looked at the ip and ebtables commands (especially -t broute). While the concepts sorta-kinda make sense, I'm completely lost in the details. Edit: In the perverse case that a system on one of my LAN segments has the same IP address as one of the radios, or as eth1 on the ARM-Ubuntu boards, a VLAN won't work. Which I believe means I need to tunnel all traffic between the two eth0 interfaces to get that "like a wire" behavior. Help? Finally, I'd like to have a way to temporarily expose services on the ARM boards (ssh) and the radios (web) for maintenance purposes. Ideally, it would expose an IP address with ssh available on port 22. Once connected, I figure I'd start an X11 session and run a browser on the ARM board to access the radios. Or something. I could login via the console to enable/disable this, or perhaps could use a GPIO to trigger a script. I feel I've identified most of the pieces needed to make all this happen, but I have no idea how to combine them to make a working system. Thanks!

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