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• Anatomy of a serialization killer

  - by Brian Donahue

  As I had mentioned last month, I have been working on a project to create an easy-to-use managed debugger. It's still an internal tool that we use at Red Gate as part of product support to analyze application errors on customer's computers, and as such, should be easy to use and not require installation. Since the project has got rather large and important, I had decided to use SmartAssembly to protect all of my hard work. This was trivial for the most part, but the loading and saving of results was broken by SA after using the obfuscation, rendering the loading and saving of XML results basically useless, although the merging and error reporting was an absolute godsend and definitely worth the price of admission. (Well, I get my Red Gate licenses for free, but you know what I mean!)My initial reaction was to simply exclude the serializable results class and all of its' members from obfuscation, and that was just dandy, but a few weeks on I decided to look into exactly why serialization had broken and change the code to work with SA so I could write any new code to be compatible with SmartAssembly and save me some additional testing and changes to the SA project.In simple terms, SA does all that it can to prevent serialization problems, for instance, it will not obfuscate public members of a DLL and it will exclude any types with the Serializable attribute from obfuscation. This prevents public members and properties from being made private and having the name changed. If the serialization is done inside the executable, however, public members have the access changed to private and are renamed. That was my first problem, because my types were in the executable assembly and implemented ISerializable, but did not have the Serializable attribute set on them!public class RedFlagResults : ISerializable        {        }The second problem caused by the pruning feature. Although RedFlagResults had public members, they were not truly properties, and used the GetObjectData() method of ISerializable to serialize the members. For that reason, SA could not exclude these members from pruning and further broke the serialization. public class RedFlagResults : ISerializable        {                public List<RedFlag.Exception> Exceptions;                 #region ISerializable Members                 public void GetObjectData(SerializationInfo info, StreamingContext context)                {                                info.AddValue("Exceptions", Exceptions);                }                 #endregionSo to fix this, it was necessary to make Exceptions a proper property by implementing get and set on it. Also, I added the Serializable attribute so that I don't have to exclude the class from obfuscation in the SA project any more. The DoNotPrune attribute means I do not need to exclude the class from pruning.[Serializable, SmartAssembly.Attributes.DoNotPrune]        public class RedFlagResults        {                public List<RedFlag.Exception> Exceptions {get;set;}        }Similarly, the Exception class gets the Serializable and DoNotPrune attributes applied so all of its' properties are excluded from obfuscation.Now my project has some protection from prying eyes by scrambling up the code so it's harder to reverse-engineer, without breaking anything. SmartAssembly has also provided the benefit of merging so that the end-user doesn't need to extract all of the DLL files needed by RedFlag into a directory, and can be run directly from the .zip archive. When an error occurs (hey, I'm only human!), an exception report can be sent to me so I can see what went wrong without having to, er, debug the debugger.

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• Diagnosing packet loss / high latency in Ubuntu

  - by Sam Gammon

  We have a Linux box (Ubuntu 12.04) running Nginx (1.5.2), which acts as a reverse proxy/load balancer to some Tornado and Apache hosts. The upstream servers are physically and logically close (same DC, sometimes same-rack) and show sub-millisecond latency between them: PING appserver (10.xx.xx.112) 56(84) bytes of data. 64 bytes from appserver (10.xx.xx.112): icmp_req=1 ttl=64 time=0.180 ms 64 bytes from appserver (10.xx.xx.112): icmp_req=2 ttl=64 time=0.165 ms 64 bytes from appserver (10.xx.xx.112): icmp_req=3 ttl=64 time=0.153 ms We receive a sustained load of about 500 requests per second, and are currently seeing regular packet loss / latency spikes from the Internet, even from basic pings: sam@AM-KEEN ~> ping -c 1000 loadbalancer PING 50.xx.xx.16 (50.xx.xx.16): 56 data bytes 64 bytes from loadbalancer: icmp_seq=0 ttl=56 time=11.624 ms 64 bytes from loadbalancer: icmp_seq=1 ttl=56 time=10.494 ms ... many packets later ... Request timeout for icmp_seq 2 64 bytes from loadbalancer: icmp_seq=2 ttl=56 time=1536.516 ms 64 bytes from loadbalancer: icmp_seq=3 ttl=56 time=536.907 ms 64 bytes from loadbalancer: icmp_seq=4 ttl=56 time=9.389 ms ... many packets later ... Request timeout for icmp_seq 919 64 bytes from loadbalancer: icmp_seq=918 ttl=56 time=2932.571 ms 64 bytes from loadbalancer: icmp_seq=919 ttl=56 time=1932.174 ms 64 bytes from loadbalancer: icmp_seq=920 ttl=56 time=932.018 ms 64 bytes from loadbalancer: icmp_seq=921 ttl=56 time=6.157 ms --- 50.xx.xx.16 ping statistics --- 1000 packets transmitted, 997 packets received, 0.3% packet loss round-trip min/avg/max/stddev = 5.119/52.712/2932.571/224.629 ms The pattern is always the same: things operate fine for a while (<20ms), then a ping drops completely, then three or four high-latency pings (1000ms), then it settles down again. Traffic comes in through a bonded public interface (we will call it bond0) configured as such: bond0 Link encap:Ethernet HWaddr 00:xx:xx:xx:xx:5d inet addr:50.xx.xx.16 Bcast:50.xx.xx.31 Mask:255.255.255.224 inet6 addr: <ipv6 address> Scope:Global inet6 addr: <ipv6 address> Scope:Link UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 RX packets:527181270 errors:1 dropped:4 overruns:0 frame:1 TX packets:413335045 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:240016223540 (240.0 GB) TX bytes:104301759647 (104.3 GB) Requests are then submitted via HTTP to upstream servers on the private network (we can call it bond1), which is configured like so: bond1 Link encap:Ethernet HWaddr 00:xx:xx:xx:xx:5c inet addr:10.xx.xx.70 Bcast:10.xx.xx.127 Mask:255.255.255.192 inet6 addr: <ipv6 address> Scope:Link UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 RX packets:430293342 errors:1 dropped:2 overruns:0 frame:1 TX packets:466983986 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:77714410892 (77.7 GB) TX bytes:227349392334 (227.3 GB) Output of uname -a: Linux <hostname> 3.5.0-42-generic #65~precise1-Ubuntu SMP Wed Oct 2 20:57:18 UTC 2013 x86_64 GNU/Linux We have customized sysctl.conf in an attempt to fix the problem, with no success. Output of /etc/sysctl.conf (with irrelevant configs omitted): # net: core net.core.netdev_max_backlog = 10000 # net: ipv4 stack net.ipv4.tcp_ecn = 2 net.ipv4.tcp_sack = 1 net.ipv4.tcp_fack = 1 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_tw_recycle = 0 net.ipv4.tcp_timestamps = 1 net.ipv4.tcp_window_scaling = 1 net.ipv4.tcp_no_metrics_save = 1 net.ipv4.tcp_max_syn_backlog = 10000 net.ipv4.tcp_congestion_control = cubic net.ipv4.ip_local_port_range = 8000 65535 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_synack_retries = 2 net.ipv4.tcp_thin_dupack = 1 net.ipv4.tcp_thin_linear_timeouts = 1 net.netfilter.nf_conntrack_max = 99999999 net.netfilter.nf_conntrack_tcp_timeout_established = 300 Output of dmesg -d, with non-ICMP UFW messages suppressed: [508315.349295 < 19.852453>] [UFW BLOCK] IN=bond1 OUT= MAC=<mac addresses> SRC=118.xx.xx.143 DST=50.xx.xx.16 LEN=68 TOS=0x00 PREC=0x00 TTL=51 ID=43221 PROTO=ICMP TYPE=3 CODE=1 [SRC=50.xx.xx.16 DST=118.xx.xx.143 LEN=40 TOS=0x00 PREC=0x00 TTL=249 ID=10220 DF PROTO=TCP SPT=80 DPT=53817 WINDOW=8190 RES=0x00 ACK FIN URGP=0 ] [517787.732242 < 0.443127>] Peer 190.xx.xx.131:59705/80 unexpectedly shrunk window 1155488866:1155489425 (repaired) How can I go about diagnosing the cause of this problem, on a Debian-family Linux box?

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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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• SOLVED Install MythTV & 11.10 on Lenovo S12 (Intel atom) with wireless

  - by keepitsimpleengineer

  This is how I installed Ubuntu 11.10 and MythTV client on my Lenovo S12 (Intel Atom) laptop and use it using WiFi (see additional notes at end). I did this because the upgrade from 11.04 bricked the laptop. Note that the partitions on the Lenovo standard disk were already in place for this installation. Also note that my LAN is setup for fixed IP addresses. Downloaded and burned 11.10 x86 Desktop Ubuntu CD Connected the power supply cord, LAN wire and the external DVD USB drive. Ran Windows XP and made sure performance level "Performance" was set and "Wireless" was enabled. Booted S12 from CD Disabled Networking from icon on upper left panel icon Edited Connections… "Wired connection 1" ? Set IP address, accepted default netmask and set gateway. Also set DNS server. Good idea to check "Connection Information" here to verify everything's O.K. Selected Install Ubuntu from the initial "Install" window Verified the three items were checked (required disk space available, plugged into a power source, & connected to the Internet) Selected Download updates while installing and third party software. Hit Continue… At wireless selected don't want to connect…WiFi…now. Continue… At Installation type, selected Something else. Continue… At partition tale, selected the ext4 Linux partition, set the mount point as "/", and marked for formatting. Here I selected the main disk (/sda) for installing the boot manager. Continue… Selected or verified my Time zone. Continue… Selected my keyboard layout. Continue… Filled in the who are you fields. Make sure password is required to sign in is checked. Continue… Chose a picture. Continue… I selected import no accounts. Continue… Wait as the Install creeps along. If your screen goes blank, tap the space bar ? apparently the screen saver/power plan does this. There are several progress bars. The longest was "Installing system", and it was the next to the last one. Installation Complete window appears, Restart Now… Wait as it stops, The screen blanks then the message "…remove…media…close tray…press enter" I just unplugged the USB DVD and hit enter… It was disheartening but the screen turned Ubuntu Purple-beige and nothing happened, so I help down the power key until it shut down, the pressed it again and the Grub Boot screen appeared. Select Ubuntu… 25.The screen went blank with the little flashing underscore cursor on it and the disk light would occasionally flash. I hit the enter key and eventuality Ubuntu started. After a somewhat long time the unity desktop appeared. 11.10, unlike earlier versions, retains the connection information. Check this by checking the network icon on the upper left applet panel. Here the touch-pad·mouse quit working and I had to reboot. It takes and extremely long time to boot, sometimes requiring several power off/ power on (cold boot). You can try to get the default network manager to work, but it might not, it didn't on mine for WiFi. Thanks to: Chris at URL here's what to do… disconnect your wired Internet connection. input your wireless information into network manager open a terminal (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "terminal". Might be a good idea to drag and drop the terminal icon to the terminal, it's easy to get rid of later. click to open a terminal, and type in: sudo rmmod acer_wmi && echo "blacklist acer_wmi" >> /etc/modprobe.d/blacklist.conf and hit enter. type in your password as asked. if you have correctly entered your WiFi information and you are near your AP, you should connect immediately if not, see the URL above ? you might need to replace "network manager" with "wicd" ? I did with 11.04. Update the new 11.10, in the upper left panel applet weird·gear icon is menu with a line about updating. It's the new way to invoke Update Manager. Your lenovo S12 (intel atom) should now run the new unity Ubuntu. Point your elbow at the ceiling and pat yourself on the back. Installing Mythbuntu Client 24.1 Open mythbuntu.org/repos (I urge you not to directly use Ubuntu Software Center for this) Install Mythbuntu Repos Save the file (in ~/Downloads, the default) Run the file ? it will update your repositories so that you will get the proper installation sources ? it will start Ubuntu Software Center to do this ? Click Install… You will need your password. Debconf window will open, select by making sure check mark is in the little box "Would you like to activate…". Forward… Which version? At the time of writing the current "Stable" version was 24.1, select 0.24.x… Forward… Read the message, then forward… Delete the downloaded file. Install synaptic (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "synaptic". Click on the synaptic icon. Ubuntu Software Center will open and allow you to install synaptic package manager. Open Synaptic (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "Synaptic". Might be a good idea to drag and drop the terminal icon to the terminal, it's easy to get rid of later. Run synaptic, read the intro, and close the intro window. Type in mythbuntu-control-centre in the Quick filter text box, and then select it "Mark for installation" by clicking on the box next to it's name. Marvel at the additional to be installed items, then select "?Mark"… At the top of the synaptic window click on the "? Apply" button. Marvel at the amount of stuff to be installed, the click on "Apply". When finished, close finished window and synaptic. Open mythbuntu-control-centre (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "mythbuntu". Might be a good idea to drag and drop the mythbuntu-control-centre icon to the terminal, it's easy to get rid of later. You can now configure and install the frontend. Go down the icon totem on the right side of the window and click as needed… System roles. ? No Backend, Desktop Frontend, and Ubuntu Desktop. Apply… & Apply changes… & Password… MySQL Configuration ? from backend ? Setup General Alt-N(ext) Alt-N(ext) Stetting Access Setup PIN code: ~~~~ Input Security key and click "Test Connection", if ?, then Apply… & Apply… {note: for some inexplicable reason, control centre hung on this, but when I restarted it, it was set properly} Graphics drivers, When I did this, only the Broadcom wireless driver showed up. I closed without doing anything. Services. I enabled SSH & Samba. Apply… & Apply… Repositories. Asked & Answered. MythExport. Pass, I believe it requires backend on the same system. Proprietary Codec Support. Check to enable, Apply… & Apply… System Updates. No action necessary, will be a part of the Ubuntu update mechanism. Themes and Artwork. For themes, I selected Enable/Update all. Apply… & Apply… Infrared & Startup behavior and Plugins. Defer until you know more. Close software centre. Open mythTV (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "mythTV". Might be a good idea to drag and drop the mythTV icon to the terminal, it's easy to get rid of later. Incorrect Group Membership. Fix this by clicking "Yes"… Log out/end. Do this by clicking "Yes"… For my Lenovo S12, I had to manually restart Ubuntu - and still with the very long restart…/no start/cold boot/reboot/pressing the shift key required Open mythTV (unity dash, top of icon totem, open, and make sure the ruler&pen icon on the bottom is selected, 2nd from left) type in "mythTV". Might be a good idea to drag and drop the mythTV icon to the terminal, it's easy to get rid of later. Will open with Select country & language. Do so. then get message with "No", hit "Ok" and arrive at the data base Configuration 1/2 screen. You will need your brackend password, from backend ? Setup General Database Configuration 1/2 Password:~? Enter this Hit Alt-n to go to the next page. Select "Use custom id…", then enter a custom ID, I use the machine's name. Hit finish, and MythTV should start up with all default settings. For the lenovo S12, the first thing you want to do is to set Playback profiles to "Normal". From Setup TV Settings Playback Alt-N(ext) Alt-N(ext) Playback Profiles (3/8) : Change Current Video Playback Profile to "Normal". You can fiddle with this setting later. For the lenovo S12, the second thing is to get the sound going. From Setup General Alt-N(ext) Alt-N(ext) Alt-N(ext) Audio System: The top of the screen is a button title "Scan for audio devices", move the highlight there and press the Space bar. Then Tab down to Audio Output Device: and left-right arrow until "ALSA:hw:Card=Intel,DEV=0" is selected. Then Alt-N(ext) until "Finish". Now you should have sound. You should now have MythTV working nicely on the Lenovo S12 Notes about wireless: Running Lenovo S12 on wireless is demanding on both power and WiFi connection. Best results will be obtained when running on power and wired connection. I run my S12 on wireless, actually two serial connections with two access points, something that is not easy to achieve. Here Mythbuntu client-server (in den) <? wireless link 1 <?office LAN? wireless link 2 <? Lenovo S12 Ubuntu 11.10 The office LAN is fixed IP behind an Untangle firewall router. There is another MythTV client on Ubuntu 10.10 computer in the office (which has always worked well). ProblemMythbuntu\Win7 client hangs with frozen frames, short segment of audio repeating. Hardware Rosewill RNX-G300EX IEEE 802.11b/g PCI Wireless Card on client-server 2 Linksys WRT54GL wireless broadband routers on LAN for link1 and link 2 WRT54GL FirmwareDD-WRT v24-sp2(07/22/09) voip set up to act as an access point. Note? many people advised this was an unworkable scheme, and in probably most cases it will be. Solution? Set up DD-WRT with the following Wireless settings… Basic Channel: Different fixed channels at least 4 difference, I use 6 & 11 Basic Sensitivity Range (ACK timing): 50 MAC filter use filter: Enable, Selected Permit only clients listed to access… Requires adding MAC addresses in "Edit MAC Filter List" This causes the 54GL's to ignore any but the listed MAC address, down side, no "guest" capability. Advanced Basic rate: All Advanced CTS Protection Mode: Off Advanced Frame Burst: Enable Advanced Max associate clients: 4 for client link 2, 1 for client-server link 1 Advanced AP isolation: Enable Advanced Preamble: Short Advanced Afterburner: On Advanced Wireless GUI access: Off Advanced WMM support: Off Other settings: default for supplied firmware. Why I suspect this worked? The 54GL Access Points's with the firmware's setting are set to handle a multiple client, wide area situation. With these mods I reconfigured them for a small area, few client situation, disabling Advanced WMM probably the most important. In addition, the client mythtv when used all other users of its access point are turned off except for a Skype phone. Also, the client-server is set up to allow other connections though it's LAN connection, and these are used to connect the TV and disc players, not used when client is being used.

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• GRUB 2 problem after Mac OS X update

  - by vallllll

  I have a MacBook Pro in dual boot Mac OS X / Ubuntu 12.04 (Precise Pangolin). When I boot it I have a rEFIt menu, and I can chose between Mac OS X and Linux. A few days ago I have updated Mac OS X from 10.7 (Lion) to 10.8 (Mountain Lion) using a .dmg image provided by my company. Since then when I select Linux in rEFIt it says: No bootable device --insert boot disk and press any key I have tried going to rEFIt partitioning tool. This is what I got: As suggested in Mac OSX Mavericks update rEFIT broken I wanted to fix the issue the same way as AndrewM, but I don't have the option "MBR table must be updated". Then I booted on Ubuntu 12.04 CD, chose repair broken system, chose root patition /dev/sda6 as this is where my Ubuntu file system is. I got a shell, but I don't really know how to repair the poblem since if it was just Windows dual boot. A GRUB update would solve the issue, but here I don't know where the GRUB 2 is installed. Here are results from Parted, and it is a bit confusing for me as the Mac partition is the one with boot: As you can see the entry 1 is an EFI system partition and is the boot partition, so I wonder if I should install GRUB there or in sda6, which is the Ubuntu filesystem. I am not sure should I work on rEFIt shell or Ubuntu. Unfortunately, I don't remember where GRUB was before update. UPDATE: using same link above I have tried RoundSparrow hilltx answer and installed rEFInd, but the result is same.... still no bootable device when I select Linux. UPDATE 2: just used alternate CD again, mounted on /dev/sda6 and the ran update-grub. It seemed to wok and started listing all my kernels. But after rebooting several times still no bootable device when I select Linux in rEFInd. UDATE 3: Have tried to boot from Ubuntu cd and select "boot from first available filesystem. I got error and dropped to grub rescue shell. I even followed the indications on this link but was unable to boot as I tried to use sdb6 but no luck UPDATE 4 as per Rob Smith request here is out put from ls -l $(find /EFI -iname "*.efi") *MACOSX -rw-r--r--@ 1 root admin 55048 29 oct 17:44 /EFI/refind/drivers_x64/btrfs_x64.efi -rw-r--r--@ 1 root admin 38888 29 oct 17:44 /EFI/refind/drivers_x64/ext2_x64.efi -rw-r--r--@ 1 root admin 39304 29 oct 17:44 /EFI/refind/drivers_x64/ext4_x64.efi -rw-r--r--@ 1 root admin 43432 29 oct 17:44 /EFI/refind/drivers_x64/hfs_x64.efi -rw-r--r--@ 1 root admin 38984 29 oct 17:44 /EFI/refind/drivers_x64/iso9660_x64.efi -rw-r--r--@ 1 root admin 43656 29 oct 17:44 /EFI/refind/drivers_x64/reiserfs_x64.efi -rw-r--r--@ 1 root admin 175016 29 oct 17:44 /EFI/refind/refind_x64.efi -rw-rw-r-- 1 root admin 73232 7 mar 2010 /EFI/tools/dbounce.efi -rw-rw-r-- 1 root admin 763248 7 mar 2010 /EFI/tools/dhclient.efi -rw-rw-r-- 1 root admin 67024 7 mar 2010 /EFI/tools/drawbox.efi -rw-rw-r-- 1 root admin 71312 7 mar 2010 /EFI/tools/dumpfv.efi -rw-rw-r-- 1 root admin 84848 7 mar 2010 /EFI/tools/dumpprot.efi -rw-rw-r-- 1 root admin 472912 7 mar 2010 /EFI/tools/ed.efi -rw-rw-r-- 1 root admin 143856 7 mar 2010 /EFI/tools/edit.efi -rw-rw-r-- 1 root admin 1801008 7 mar 2010 /EFI/tools/ftp.efi -rw-r--r--@ 1 root admin 47848 29 oct 17:44 /EFI/tools/gptsync_x64.efi -rw-rw-r-- 1 root admin 320560 7 mar 2010 /EFI/tools/hexdump.efi -rw-rw-r-- 1 root admin 286384 7 mar 2010 /EFI/tools/hostname.efi -rw-rw-r-- 1 root admin 534416 7 mar 2010 /EFI/tools/ifconfig.efi -rw-rw-r-- 1 root admin 395344 7 mar 2010 /EFI/tools/loadarg.efi -rw-rw-r-- 1 root admin 587408 7 mar 2010 /EFI/tools/ping.efi -rw-rw-r-- 1 root admin 730416 7 mar 2010 /EFI/tools/pppd.efi -rw-rw-r-- 1 root admin 561360 7 mar 2010 /EFI/tools/route.efi -rw-rw-r-- 1 root admin 1961712 7 mar 2010 /EFI/tools/shell.efi -rw-rw-r-- 1 root admin 750224 7 mar 2010 /EFI/tools/tcpipv4.efi -rw-rw-r-- 1 root admin 4048 7 mar 2010 /EFI/tools/textmode.efi -rw-rw-r-- 1 root admin 320656 7 mar 2010 /EFI/tools/which.efi *LINUX

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• Strange enduser experience with Liferay, Glassfish and Apache on RedHat

  - by Pete Helgren

  Tried multiple forums to get to the bottom of this. I hope I can get some direction here: Here is the stack I am working with: Red Hat Enterprise Linux Server release 5.6 (Tikanga) Liferay 6.0.6 on Glassfish 3.0.1 MySQL 5.0.77 Apache 2.2.3 The Liferay portal provides a variety of portlets to end users. Static content (web pages), static resources (primarily pdf and mp3 files 1mb - 80mb in size), File upload and download capabilities (primarily 40-60mb mp3 files) and online streaming of those MP3 files. Here is the strange end user experiences: Under normal load: (20-30) users uploading, downloading or streaming files and 20-30 accessing static content (some of it downloads), we see the following: 1) Clicking a link triggers the download of a portion of an MP3 (the portion is a few seconds long). 2) Clicking on a link tiggers the download of the page content rather than rendering. 3) Clicking a link causes the page to dump binary data to the end user rather than the expected content. 4) Clicking a link returns the text of a javascript file rather than rendering the page. Each occurrence is totally random (or appears so). Sometimes it works, sometimes it doesn't. It seems to have no relation to browser or client OS. The strange events seem to occur much more frequently when using an SSL connection rather than regular http. Apache serves as a proxy server only (reverse). It basically passes all the requests through to Glassfish. There isn't any static content proxy served by Apache. We rebuilt the entire stack from scratch and redeployed the portlet wars and still have the same issues. Liferay is running as a single server (not clustered). We disabled mod_cache in Apache. The problems are more frequent as the server load grows. This morning the load is pretty light and we are seeing few problems but the use of the site will grow, particularly tonight around 9pm CST through Wednesday morning. You could try the site (http://preview.bsfinternational.org) during those times and I would expect that you might experience one of the weirdnesses as you randomly click links on the site (https is invoked only when signed in). Again, https seems to exacerbate the issue. This seems very much like a caching issue but I don't know where in the stack to start peeling the onion. Apache? Liferay? Glassfish? MySQL? Maybe even Redhat? We are stumped and most forums we have posted to (LifeRay and Glassfish) have returned very few suggestions. I just need an idea of where to start looking. I understand that we could have a portlet EDIT: Opening the files in a Hex editor that appear to be pages that download rather than render, we see that the first 4000 characters are "junk" and then the "HTTP/1.1 ...." 'normal' header is seen. So something is dumping a jumble of characters up to offset 4000 (when viewing it in a Hex editor). Perhaps a clue? Ideas?

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• Neighbour table overflow on Linux hosts related to bridging and ipv6

  - by tim

  Note: I already have a workaround for this problem (as described below) so this is only a "want-to-know" question. I have a productive setup with around 50 hosts including blades running xen 4 and equallogics providing iscsi. All xen dom0s are almost plain Debian 5. The setup includes several bridges on every dom0 to support xen bridged networking. In total there are between 5 and 12 bridges on each dom0 servicing one vlan each. None of the hosts has routing enabled. At one point in time we moved one of the machines to a new hardware including a raid controller and so we installed an upstream 3.0.22/x86_64 kernel with xen patches. All other machines run debian xen-dom0-kernel. Since then we noticed on all hosts in the setup the following errors every ~2 minutes: [55888.881994] __ratelimit: 908 callbacks suppressed [55888.882221] Neighbour table overflow. [55888.882476] Neighbour table overflow. [55888.882732] Neighbour table overflow. [55888.883050] Neighbour table overflow. [55888.883307] Neighbour table overflow. [55888.883562] Neighbour table overflow. [55888.883859] Neighbour table overflow. [55888.884118] Neighbour table overflow. [55888.884373] Neighbour table overflow. [55888.884666] Neighbour table overflow. The arp table (arp -n) never showed more than around 20 entries on every machine. We tried the obvious tweaks and raised the /proc/sys/net/ipv4/neigh/default/gc_thresh* values. FInally to 16384 entries but no effect. Not even the interval of ~2 minutes changed which lead me to the conclusion that this is totally unrelated. tcpdump showed no uncommon ipv4 traffic on any interface. The only interesting finding from tcpdump were ipv6 packets bursting in like: 14:33:13.137668 IP6 fe80::216:3eff:fe1d:9d01 > ff02::1:ff1d:9d01: HBH ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:ff1d:9d01, length 24 14:33:13.138061 IP6 fe80::216:3eff:fe1d:a8c1 > ff02::1:ff1d:a8c1: HBH ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:ff1d:a8c1, length 24 14:33:13.138619 IP6 fe80::216:3eff:fe1d:bf81 > ff02::1:ff1d:bf81: HBH ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:ff1d:bf81, length 24 14:33:13.138974 IP6 fe80::216:3eff:fe1d:eb41 > ff02::1:ff1d:eb41: HBH ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:ff1d:eb41, length 24 which placed the idea in my mind that the problem maybe related to ipv6, since we have no ipv6 services in this setup. The only other hint was the coincidence of the host upgrade with the beginning of the problems. I powered down the host in question and the errors were gone. Then I subsequently took down the bridges on the host and when i took down (ifconfig down) one particularly bridge: br-vlan2159 Link encap:Ethernet HWaddr 00:26:b9:fb:16:2c inet6 addr: fe80::226:b9ff:fefb:162c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:120 errors:0 dropped:0 overruns:0 frame:0 TX packets:9 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:5286 (5.1 KiB) TX bytes:726 (726.0 B) eth0.2159 Link encap:Ethernet HWaddr 00:26:b9:fb:16:2c inet6 addr: fe80::226:b9ff:fefb:162c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1801 errors:0 dropped:0 overruns:0 frame:0 TX packets:20 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:126228 (123.2 KiB) TX bytes:1464 (1.4 KiB) bridge name bridge id STP enabled interfaces ... br-vlan2158 8000.0026b9fb162c no eth0.2158 br-vlan2159 8000.0026b9fb162c no eth0.2159 The errors went away again. As you can see the bridge holds no ipv4 address and it's only member is eth0.2159 so no traffic should cross it. Bridge and interface .2159 / .2157 / .2158 which are in all aspects identical apart from the vlan they are connected to had no effect when taken down. Now I disabled ipv6 on the entire host via sysctl net.ipv6.conf.all.disable_ipv6 and rebooted. After this even with bridge br-vlan2159 enabled no errors occur. Any ideas are welcome.

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• Sweet and Sour Source Control

  - by Tony Davis

  Most database developers don't use Source Control. A recent anonymous poll on SQL Server Central asked its readers "Which Version Control system do you currently use to store you database scripts?" The winner, with almost 30% of the vote was...none: "We don't use source control for database scripts". In second place with almost 28% of the vote was Microsoft's VSS. VSS? Given its reputation for being buggy, unstable and lacking most of the basic features required of a proper source control system, answering VSS is really just another way of saying "I don't use Source Control". At first glance, it's a surprising thought. You wonder how database developers can work in a team and find out what changed, when the system worked before but is now broken; to work out what happened to their changes that now seem to have vanished; to roll-back a mistake quickly so that the rest of the team have a functioning build; to find instantly whether a suspect change has been deployed to production. Unfortunately, the survey didn't ask about the scale of the database development, and correlate the two questions. If there is only one database developer within a schema, who has an automated approach to regular generation of build scripts, then the need for a formal source control system is questionable. After all, a database stores far more about its metadata than a traditional compiled application. However, what is meat for a small development is poison for a team-based development. Here, we need a form of Source Control that can reconcile simultaneous changes, store the history of changes, derive versions and builds and that can cope with forks and merges. The problem comes when one borrows a solution that was designed for conventional programming. A database is not thought of as a "file", but a vast, interdependent and intricate matrix of tables, indexes, constraints, triggers, enumerations, static data and so on, all subtly interconnected. It is an awkward fit. Subversion with its support for merges and forks, and the tolerance of different work practices, can be made to work well, if used carefully. It has a standards-based architecture that allows it to be used on all platforms such as Windows Mac, and Linux. In the words of Erland Sommerskog, developers should "just do it". What's in a database is akin to a "binary file", and the developer must work only from the file. You check out the file, edit it, and save it to disk to compile it. Dependencies are validated at this point and if you've broken anything (e.g. you renamed a column and broke all the objects that reference the column), you'll find out about it right away, and you'll be forced to fix it. Nevertheless, for many this is an alien way of working with SQL Server. Subversion is the powerhouse, not the GUI. It doesn't work seamlessly with your existing IDE, and that usually means SSMS. So the question then becomes more subtle. Would developers be less reluctant to use a fully-featured source (revision) control system for a team database development if they had a turn-key, reliable system that fitted in with their existing work-practices? I'd love to hear what you think. Cheers, Tony.

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• Diving into OpenStack Network Architecture - Part 2 - Basic Use Cases

  - by Ronen Kofman

    rkofman Normal rkofman 4 138 2014-06-05T03:38:00Z 2014-06-05T05:04:00Z 3 2735 15596 Oracle Corporation 129 36 18295 12.00 Clean Clean false false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} In the previous post we reviewed several network components including Open vSwitch, Network Namespaces, Linux Bridges and veth pairs. In this post we will take three simple use cases and see how those basic components come together to create a complete SDN solution in OpenStack. With those three use cases we will review almost the entire network setup and see how all the pieces work together. The use cases we will use are: 1.       Create network – what happens when we create network and how can we create multiple isolated networks 2.       Launch a VM – once we have networks we can launch VMs and connect them to networks. 3.       DHCP request from a VM – OpenStack can automatically assign IP addresses to VMs. This is done through local DHCP service controlled by OpenStack Neutron. We will see how this service runs and how does a DHCP request and response look like. In this post we will show connectivity, we will see how packets get from point A to point B. We first focus on how a configured deployment looks like and only later we will discuss how and when the configuration is created. Personally I found it very valuable to see the actual interfaces and how they connect to each other through examples and hands on experiments. After the end game is clear and we know how the connectivity works, in a later post, we will take a step back and explain how Neutron configures the components to be able to provide such connectivity.  We are going to get pretty technical shortly and I recommend trying these examples on your own deployment or using the Oracle OpenStack Tech Preview. Understanding these three use cases thoroughly and how to look at them will be very helpful when trying to debug a deployment in case something does not work. Use case #1: Create Network Create network is a simple operation it can be performed from the GUI or command line. When we create a network in OpenStack the network is only available to the tenant who created it or it could be defined as “shared” and then it can be used by all tenants. A network can have multiple subnets but for this demonstration purpose and for simplicity we will assume that each network has exactly one subnet. Creating a network from the command line will look like this: # neutron net-create net1 Created a new network: +---------------------------+--------------------------------------+ | Field                     | Value                                | +---------------------------+--------------------------------------+ | admin_state_up            | True                                 | | id                        | 5f833617-6179-4797-b7c0-7d420d84040c | | name                      | net1                                 | | provider:network_type     | vlan                                 | | provider:physical_network | default                              | | provider:segmentation_id  | 1000                                 | | shared                    | False                                | | status                    | ACTIVE                               | | subnets                   |                                      | | tenant_id                 | 9796e5145ee546508939cd49ad59d51f     | +---------------------------+--------------------------------------+ Creating a subnet for this network will look like this: # neutron subnet-create net1 10.10.10.0/24 Created a new subnet: +------------------+------------------------------------------------+ | Field            | Value                                          | +------------------+------------------------------------------------+ | allocation_pools | {"start": "10.10.10.2", "end": "10.10.10.254"} | | cidr             | 10.10.10.0/24                                  | | dns_nameservers  |                                                | | enable_dhcp      | True                                           | | gateway_ip       | 10.10.10.1                                     | | host_routes      |                                                | | id               | 2d7a0a58-0674-439a-ad23-d6471aaae9bc           | | ip_version       | 4                                              | | name             |                                                | | network_id       | 5f833617-6179-4797-b7c0-7d420d84040c           | | tenant_id        | 9796e5145ee546508939cd49ad59d51f               | +------------------+------------------------------------------------+ We now have a network and a subnet, on the network topology view this looks like this: Now let’s dive in and see what happened under the hood. Looking at the control node we will discover that a new namespace was created: # ip netns list qdhcp-5f833617-6179-4797-b7c0-7d420d84040c   The name of the namespace is qdhcp-<network id> (see above), let’s look into the namespace and see what’s in it: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 12: tap26c9b807-7c: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN     link/ether fa:16:3e:1d:5c:81 brd ff:ff:ff:ff:ff:ff     inet 10.10.10.3/24 brd 10.10.10.255 scope global tap26c9b807-7c     inet6 fe80::f816:3eff:fe1d:5c81/64 scope link        valid_lft forever preferred_lft forever   We see two interfaces in the namespace, one is the loopback and the other one is an interface called “tap26c9b807-7c”. This interface has the IP address of 10.10.10.3 and it will also serve dhcp requests in a way we will see later. Let’s trace the connectivity of the “tap26c9b807-7c” interface from the namespace.  First stop is OVS, we see that the interface connects to bridge  “br-int” on OVS: # ovs-vsctl show 8a069c7c-ea05-4375-93e2-b9fc9e4b3ca1     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-ex         Port br-ex             Interface br-ex                 type: internal     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port "tap26c9b807-7c"             tag: 1             Interface "tap26c9b807-7c"                 type: internal         Port br-int             Interface br-int                 type: internal     ovs_version: "1.11.0"   In the picture above we have a veth pair which has two ends called “int-br-eth2” and "phy-br-eth2", this veth pair is used to connect two bridge in OVS "br-eth2" and "br-int". In the previous post we explained how to check the veth connectivity using the ethtool command. It shows that the two are indeed a pair: # ethtool -S int-br-eth2 NIC statistics:      peer_ifindex: 10 . .   #ip link . . 10: phy-br-eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 . . Note that “phy-br-eth2” is connected to a bridge called "br-eth2" and one of this bridge's interfaces is the physical link eth2. This means that the network which we have just created has created a namespace which is connected to the physical interface eth2. eth2 is the “VM network” the physical interface where all the virtual machines connect to where all the VMs are connected. About network isolation: OpenStack supports creation of multiple isolated networks and can use several mechanisms to isolate the networks from one another. The isolation mechanism can be VLANs, VxLANs or GRE tunnels, this is configured as part of the initial setup in our deployment we use VLANs. When using VLAN tagging as an isolation mechanism a VLAN tag is allocated by Neutron from a pre-defined VLAN tags pool and assigned to the newly created network. By provisioning VLAN tags to the networks Neutron allows creation of multiple isolated networks on the same physical link.  The big difference between this and other platforms is that the user does not have to deal with allocating and managing VLANs to networks. The VLAN allocation and provisioning is handled by Neutron which keeps track of the VLAN tags, and responsible for allocating and reclaiming VLAN tags. In the example above net1 has the VLAN tag 1000, this means that whenever a VM is created and connected to this network the packets from that VM will have to be tagged with VLAN tag 1000 to go on this particular network. This is true for namespace as well, if we would like to connect a namespace to a particular network we have to make sure that the packets to and from the namespace are correctly tagged when they reach the VM network. In the example above we see that the namespace interface “tap26c9b807-7c” has vlan tag 1 assigned to it, if we examine OVS we see that it has flows which modify VLAN tag 1 to VLAN tag 1000 when a packet goes to the VM network on eth2 and vice versa. We can see this using the dump-flows command on OVS for packets going to the VM network we see the modification done on br-eth2: #  ovs-ofctl dump-flows br-eth2 NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18669.401s, table=0, n_packets=857, n_bytes=163350, idle_age=25, priority=4,in_port=2,dl_vlan=1 actions=mod_vlan_vid:1000,NORMAL  cookie=0x0, duration=165108.226s, table=0, n_packets=14, n_bytes=1000, idle_age=5343, hard_age=65534, priority=2,in_port=2 actions=drop  cookie=0x0, duration=165109.813s, table=0, n_packets=1671, n_bytes=213304, idle_age=25, hard_age=65534, priority=1 actions=NORMAL   For packets coming from the interface to the namespace we see the following modification: #  ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18690.876s, table=0, n_packets=1610, n_bytes=210752, idle_age=1, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL  cookie=0x0, duration=165130.01s, table=0, n_packets=75, n_bytes=3686, idle_age=4212, hard_age=65534, priority=2,in_port=1 actions=drop  cookie=0x0, duration=165131.96s, table=0, n_packets=863, n_bytes=160727, idle_age=1, hard_age=65534, priority=1 actions=NORMAL   To summarize we can see that when a user creates a network Neutron creates a namespace and this namespace is connected through OVS to the “VM network”. OVS also takes care of tagging the packets from the namespace to the VM network with the correct VLAN tag and knows to modify the VLAN for packets coming from VM network to the namespace. Now let’s see what happens when a VM is launched and how it is connected to the “VM network”. Use case #2: Launch a VM Launching a VM can be done from Horizon or from the command line this is how we do it from Horizon: Attach the network: And Launch Once the virtual machine is up and running we can see the associated IP using the nova list command : # nova list +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | ID                                   | Name         | Status | Task State | Power State | Networks        | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | 3707ac87-4f5d-4349-b7ed-3a673f55e5e1 | Oracle Linux | ACTIVE | None       | Running     | net1=10.10.10.2 | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ The nova list command shows us that the VM is running and that the IP 10.10.10.2 is assigned to this VM. Let’s trace the connectivity from the VM to VM network on eth2 starting with the VM definition file. The configuration files of the VM including the virtual disk(s), in case of ephemeral storage, are stored on the compute node at/var/lib/nova/instances/<instance-id>/. Looking into the VM definition file ,libvirt.xml,  we see that the VM is connected to an interface called “tap53903a95-82” which is connected to a Linux bridge called “qbr53903a95-82”: <interface type="bridge">       <mac address="fa:16:3e:fe:c7:87"/>       <source bridge="qbr53903a95-82"/>       <target dev="tap53903a95-82"/>     </interface>   Looking at the bridge using the brctl show command we see this: # brctl show bridge name     bridge id               STP enabled     interfaces qbr53903a95-82          8000.7e7f3282b836       no              qvb53903a95-82                                                         tap53903a95-82    The bridge has two interfaces, one connected to the VM (“tap53903a95-82 “) and another one ( “qvb53903a95-82”) connected to “br-int” bridge on OVS: # ovs-vsctl show 83c42f80-77e9-46c8-8560-7697d76de51c     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-int         Port br-int             Interface br-int                 type: internal         Port "int-br-eth2"             Interface "int-br-eth2"         Port "qvo53903a95-82"             tag: 3             Interface "qvo53903a95-82"     ovs_version: "1.11.0"   As we showed earlier “br-int” is connected to “br-eth2” on OVS using the veth pair int-br-eth2,phy-br-eth2 and br-eth2 is connected to the physical interface eth2. The whole flow end to end looks like this: VM è tap53903a95-82 (virtual interface)è qbr53903a95-82 (Linux bridge) è qvb53903a95-82 (interface connected from Linux bridge to OVS bridge br-int) è int-br-eth2 (veth one end) è phy-br-eth2 (veth the other end) è eth2 physical interface. The purpose of the Linux Bridge connecting to the VM is to allow security group enforcement with iptables. Security groups are enforced at the edge point which are the interface of the VM, since iptables nnot be applied to OVS bridges we use Linux bridge to apply them. In the future we hope to see this Linux Bridge going away rules.  VLAN tags: As we discussed in the first use case net1 is using VLAN tag 1000, looking at OVS above we see that qvo41f1ebcf-7c is tagged with VLAN tag 3. The modification from VLAN tag 3 to 1000 as we go to the physical network is done by OVS  as part of the packet flow of br-eth2 in the same way we showed before. To summarize, when a VM is launched it is connected to the VM network through a chain of elements as described here. During the packet from VM to the network and back the VLAN tag is modified. Use case #3: Serving a DHCP request coming from the virtual machine In the previous use cases we have shown that both the namespace called dhcp-<some id> and the VM end up connecting to the physical interface eth2  on their respective nodes, both will tag their packets with VLAN tag 1000.We saw that the namespace has an interface with IP of 10.10.10.3. Since the VM and the namespace are connected to each other and have interfaces on the same subnet they can ping each other, in this picture we see a ping from the VM which was assigned 10.10.10.2 to the namespace: The fact that they are connected and can ping each other can become very handy when something doesn’t work right and we need to isolate the problem. In such case knowing that we should be able to ping from the VM to the namespace and back can be used to trace the disconnect using tcpdump or other monitoring tools. To serve DHCP requests coming from VMs on the network Neutron uses a Linux tool called “dnsmasq”,this is a lightweight DNS and DHCP service you can read more about it here. If we look at the dnsmasq on the control node with the ps command we see this: dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap26c9b807-7c --except-interface=lo --pid-file=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host --dhcp-optsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/opts --leasefile-ro --dhcp-range=tag0,10.10.10.0,static,120s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal The service connects to the tap interface in the namespace (“--interface=tap26c9b807-7c”), If we look at the hosts file we see this: # cat  /var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host fa:16:3e:fe:c7:87,host-10-10-10-2.openstacklocal,10.10.10.2   If you look at the console output above you can see the MAC address fa:16:3e:fe:c7:87 which is the VM MAC. This MAC address is mapped to IP 10.10.10.2 and so when a DHCP request comes with this MAC dnsmasq will return the 10.10.10.2.If we look into the namespace at the time we initiate a DHCP request from the VM (this can be done by simply restarting the network service in the VM) we see the following: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c tcpdump -n 19:27:12.191280 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from fa:16:3e:fe:c7:87, length 310 19:27:12.191666 IP 10.10.10.3.bootps > 10.10.10.2.bootpc: BOOTP/DHCP, Reply, length 325   To summarize, the DHCP service is handled by dnsmasq which is configured by Neutron to listen to the interface in the DHCP namespace. Neutron also configures dnsmasq with the combination of MAC and IP so when a DHCP request comes along it will receive the assigned IP. Summary In this post we relied on the components described in the previous post and saw how network connectivity is achieved using three simple use cases. These use cases gave a good view of the entire network stack and helped understand how an end to end connection is being made between a VM on a compute node and the DHCP namespace on the control node. One conclusion we can draw from what we saw here is that if we launch a VM and it is able to perform a DHCP request and receive a correct IP then there is reason to believe that the network is working as expected. We saw that a packet has to travel through a long list of components before reaching its destination and if it has done so successfully this means that many components are functioning properly. In the next post we will look at some more sophisticated services Neutron supports and see how they work. We will see that while there are some more components involved for the most part the concepts are the same. @RonenKofman

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• Hell and Diplomacy: Notes on Software Integration

  - by ericajanine

  Well, I'm getting cabin fever and short-timer's ADD all at the same time. I haven't been anywhere outside of my greater city area in FOREVER and I'm only days away from my vacation. I have brainlock because the last few days have been non-stop diffusing amazingly hostile conversations. I think I'll write about that. So then, I "do" software. At the end of the day, software is pretty straightforward. Software is that thing we love and try to make do things not currently in play, in existence. If a process around getting software to do something is broken (like most actually are), then we should acknowledge it and move on. We are professional. We are helpful beyond the normal call of duty. We live and breathe making the lives better for those apps being active in the world. But above all--the shocker: We are SERVICE. In a service frame of mind, all perspectives shift to what is best overall for system stabilization vs. what must be in production to meet business objectives. It doesn't matter how much you like or dislike the creator of said software. It doesn't matter what time you went to bed last night or if your mate appreciates your Death March attitude. Getting a product in and when is an age-old dilemma in a software environment where more than, say, 3 people are involved. We know this. Taking a servant's perspective eliminates the drama surrounding what a group of half-baked developers forgot to tell each other in the 11th hour about their trampling changes before check-in. We, my counterparts in society, get paid to deal with that drama. I get paid to diffuse that drama and make everything integrate as smoothly as possible. At the end of the day, attacking someone over a minor detail not only makes things worse, it's against the whole point of our real existence. Being in support or software integration means you are to keep your eyes on the end game. That end game? It's making a solution work for all stakeholders, not just you or your immediate superior. Development and technology groups exist because business groups need them to exist and solve their issues. The end game? Doing what is best for those business groups ultimately. Period. Note: That does not mean you let your business users solely dictate when and if something gets changed in an environment you ultimately own. That's just crazy. Software and its environments are legitimately owned by those who manage it directly, no matter how important a business group believes it is to the existence of mankind. So, you both negotiate the terms of changing that environment and only do so upon that negotiation. Diplomacy is in order. So, to finish my thoughts: If you have no ability to keep your mouth shut in a situation where a business or development group truly need your help to make something work even beyond a deadline, find another profession. Beating up someone verbally because they screw up means a service attitude is not at the forefront of your motivation for doing what is ultimately their work and their product. Software, especially integration, requires a strong will and a soft touch to keep it on track. Not a hammer covered in broken glass.

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• KVM with one host IP and a different subnet for machines

  - by Jguy

  I've already setup a KVM host with proper IP configurations, but my host had me create DHCP and use that to assign the IP's to the machines. I want to see if there's an easier way to do it (or better). Upon my first setting out on this, I didn't find anything that pointed me in the right direction. I'm coming off a fresh install of Debian 6.0 x64, so I have nothing installed. I've logged in, queried for the below information and changed the password from my host set one. I have a Debian 6.0 x64 system with the following initial network configuration (substituted 255 in place of my real first octave): # tail /etc/network/interfaces auto eth0 iface eth0 inet static address 255.9.24.80 broadcast 255.9.24.95 netmask 255.255.255.224 gateway 255.9.24.65 # default route to access subnet up route add -net 255.9.24.64 netmask 255.255.255.224 gw 255.9.24.65 eth0 I have a /29 subnet that I want the virtual machines to use from my host: IP: 255.46.187.152 /29 Mask: 255.255.255.248 Broadcast: 255.46.187.159 Usable IP addresses: 255.46.187.153 to 255.46.187.158 I like the interface of Cloudmin, so I want to try and use that if I can to administrate my guests. So, my questions: How do I set this up on the host system the best so that I can use the additional Subnet IP's on the guests and have them accessible from the internet? I also need to host a DNS server, which means one of these VM's has to have two IP's assigned to it and accessable from the outside world. How can I do that using Cloudmin? I had a question about this here: Multiple IP addresses assigned to one KVM VM But I just reformatted the entire server and am trying to figure out a better way of doing this. Machine information: # ip route show 255.9.24.64/27 via 255.9.24.65 dev eth0 255.9.24.64/27 dev eth0 proto kernel scope link src 255.9.24.80 default via 255.9.24.65 dev eth0 brctl is empty # ip addr list 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether c8:60:00:54:b5:d8 brd ff:ff:ff:ff:ff:ff inet 255.9.24.80/27 brd 255.9.24.95 scope global eth0 inet6 fe80::ca60:ff:fe54:b5d8/64 scope link valid_lft forever preferred_lft forever Thank you for any help you can provide me. EDIT: I've installed kvm and cloudmin: aptitude install qemu-kvm libvirt-bin wget http://cloudmin.virtualmin.com/gpl/scripts/cloudmin-kvm-debian-install.sh ./cloudmin-kvm-debian-install.sh Rebooted and now my network configuration looks like this: # device: eth0 iface eth0 inet manual # default route to access subnet iface br0 inet static address 255.9.24.80 netmask 255.255.255.224 broadcast 255.9.24.95 network 255.9.24.64 bridge_ports eth0 gateway 255.9.24.65 I setup in Cloudmin the Start IP as 255.46.187.153 and End IP as 255.46.187.158. The CIDR is 29 and the gateway is 255.46.187.152. I've installed a guest with ubuntuserver 12.04 x64, which was able to get and retrieve internet resources during installation, but now cannot reach anything nor can it be reached from anything. Its network configuration is: iface eth0 inet static address 255.46.187.153 netmask 255.255.255.224 broadcast 255.46.187.159 gateway 255.46.187.152 dns-nameservers <host provided nameservers> And is not able to ping google.com through DNS or direct IP, I can't ping the VM from the outside or the host. any ideas now?

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• Forcing UIInterfaceOrientation changes on iPhone

  - by Andiih

  I'm strugging with getting an iPhone application which requires just about every push or pop in the Nav Controller Stack to change orientation. Basically the first view is portrait, the second landscape the third portrait again (Yes I know this is less than ideal, but that's the design and I've got to implement it). I've been through various advice on here.... http://stackoverflow.com/questions/995723/how-do-i-detect-a-rotation-on-the-iphone-without-the-device-autorotating http://stackoverflow.com/questions/1824682/force-portrait-orientation-on-pushing-new-view-to-uinavigationviewcontroller http://stackoverflow.com/questions/181780/is-there-a-documented-way-to-set-the-iphone-orientation But without total success. Setting to link against 3.1.2 my reading of the linked articles above seems to indicate that if my portrait view pushes a view with - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return ((interfaceOrientation == UIInterfaceOrientationLandscapeRight) ); } Then then that view should appear rotated to landscape. What happens is it appears in its "broken" portrait form, then rotates correctly as the device is turned. If I pop the controller back to my portrait view (which has an appropriate shouldAutoRotate...) then that remains in broken landscape view until the device is returned to portrait orientation. I've also tried removing all the shouldautorotate messages, and instead forcing rotation by transforming the view. This kind of works, and I've figured out that by moving the status bar (which is actually hidden in my application) [UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationLandscapeRight; the keyboard will appear with the correct orientation when desired. The problem with this approach is that the status bar transform is weird and ugly when you don't have a status bar - a shadow looms over the page with each change. So. What am I missing. 1) Am I wrong in thinking that in 3.1.2 (or possibly earlier) shouldAutorotateToInterfaceOrientation should provide the desired orientation simply by pushing controllers ? 2) Is there another way of getting keyboards to appear in the correct orientation. 3) Are the undocumented API calls the way to go (please no!)

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• MySQL Connection Timeout Issue - Grails Application on Tomcat using Hibernate and ORM

  - by gav

  Hi Guys I have a small grails application running on Tomcat in Ubuntu on a VPS. I use MySql as my datastore and everything works fine unless I leave the application for more than half a day (8 hours?). I did some searching and apparently this is the default wait_timeout in mysql.cnf so after 8 hours the connection will die but Tomcat won't know so when the next user tries to view the site they will see the connection failure error. Refreshing the page will fix this but I want to get rid of the error altogether. For my version of MySql (5.0.75) I have only my.cnf and it doesn't contain such a parameter, In any case changing this parameter doesn't solve the problem. This Blog Post seems to be reporting a similar error but I still don't fully understand what I need to configure to get this fixed and also I am hoping that there is a simpler solution than another third party library. The machine I'm running on has 256MB ram and I'm trying to keep the number of programs/services running to a minimum. Is there something I can configure in Grails / Tomcat / MySql to get this to go away? Thanks in advance, Gav From my Catalina.out; 2010-04-29 21:26:25,946 [http-8080-2] ERROR util.JDBCExceptionReporter - The last packet successfully received from the server was 102,906,722 milliseconds$ 2010-04-29 21:26:25,994 [http-8080-2] ERROR errors.GrailsExceptionResolver - Broken pipe java.net.SocketException: Broken pipe at java.net.SocketOutputStream.socketWrite0(Native Method) ... 2010-04-29 21:26:26,016 [http-8080-2] ERROR util.JDBCExceptionReporter - Already closed. 2010-04-29 21:26:26,016 [http-8080-2] ERROR util.JDBCExceptionReporter - Already closed. 2010-04-29 21:26:26,017 [http-8080-2] ERROR servlet.GrailsDispatcherServlet - HandlerInterceptor.afterCompletion threw exception org.hibernate.exception.GenericJDBCException: Cannot release connection at java.lang.Thread.run(Thread.java:619) Caused by: java.sql.SQLException: Already closed. at org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:84) at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.close(PoolingDataSource.java:181) ... 1 more

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• Android RestTemplate Ok on emulator but fails on real device

  - by Hossein

  I'm using spring RestTemplate and it works perfect on emulator but if I run my app on real device I get HttpMessageNotWritableException ............ nested exception is java.net.SocketException: Broken pipe Here is some lines of my code(keep in mind my app works perfect on emulator) ............ LoggerUtil.logToFile(TAG, "url is [" + url + "]"); LoggerUtil.logToFile(TAG, "NetworkInfo - " + connectivityManager.getActiveNetworkInfo()); ResponseEntity<T> responseEntity = restTemplate.exchange(url, HttpMethod.POST, requestEntity, clazz); ............. I know my device's network works perfect because all other applications on my device are working and also using device browser I'm able to connect to my server so my server is available. My server is up and running and my device is able to connect to my server so why I get java.net.SocketException: Broken pipe ?!!!!!!! Before I call restTemplate.exchange() I log NetworkInfo and it looks ok -type: WIFI -status: CONNECTED/CONNECTED -isAvailable: true Thanks in advance. Update: It is really weird Even if I use HttpURLConnection, it works perfectly on emulator but on real device I get 400 Bad Request Here is my code HttpURLConnection con = null; try { String url = ....; LoggerUtil.logToFile(TAG, "url [" + url + "]" ); con = (HttpURLConnection) new URL(url).openConnection(); con.setRequestMethod("POST"); con.setRequestProperty("Connection", "Keep-Alive"); con.setDoInput(true); con.setDoOutput(true); con.setUseCaches(false); con.connect(); LoggerUtil.logToFile(TAG, "con.getResponseCode is " + con.getResponseCode()); LoggerUtil.logToFile(TAG, "con.getResponseMessage is " + con.getResponseMessage()); } catch(Throwable t){ LoggerUtil.logToFile(TAG, "*** failed [" + t + "]" ); } in log file I see con.getResponseCode is 400 con.getResponseMessage is Bad Request

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• split video (avi/h264) on keyframe

  - by m.sr

  Hallo. I have a big video file. ffmpeg, tcprobe and other tool say, it is an h264-stream in an AVI-container. Now i'd like to cut out small chunks form the video. Problem: The index of the video seam corrupted/destroyed. I kind of fixed this via mplayer -forceidx -saveidx <IndexFile> <BigVideoFile>. The Problem here is, that I'm now stuck with mplayer/mencoder which can use this index file via -loadidx <IndexFile>. I have tried correcting the index like described in man aviindex (mplayer -frames 0 -saveidx mpidx broken.avi ; aviindex -i mpidx -o tcindex ; avimerge -x tcindex -i broken.avi -o fixed.avi), but this didn't fix my video - meaning that most tools i've tested couldn't search in the video file. Problem: I sut out parts of the video via following command: mencoder -loadidx in.idx -ss 8578 -endpos 20 -oac faac -ovc x264 -sws 9 -lavfopts format=mp4 -x264encopts <LotsOfOpts> -of lavf -vf scale=800:-10,harddup in.avi -o out.mp4. Now here the problem is, that some videos are corrupted at the beginning. I think this is because the fact, that i do not necessarily cut at keyframe. Questions: What is the best way to fix the index of an avi "inline" so that every tool can again work as expected with it? How can i split at the keyframes? Is there an mencoder-option for this? Are Keyframes coming in a frequency? How to find out this frequency? (So with a bit of math it should be possible to calculate the next keyframe and cut there) Is ther perhaps some completely other way to split this movie? Doing it by hand is no option, i've to cut out 1000+ chunks ... Thanks a lot!

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• Custom SSL handling stopped working on Android 2.2 FroYo

  - by Eric

  For my app, Transdroid, I am connecting to remote servers via HTTP and optionally securely via HTTPS. For these HTTPS connections with the HttpClient I am using a custom SSL socket factory implementation to make sure self-signed certificates are working. Basically, I accept everything and ignore every checking of any certificate. This has been working fine for some time now, but it no longer work for Android 2.2 FroYo. When trying to connect, it will return an exception: java.io.IOException: SSL handshake failure: I/O error during system call, Broken pipe Here is how I initialize the HttpClient: SchemeRegistry registry = new SchemeRegistry(); registry.register(new Scheme("http", new PlainSocketFactory(), 80)); registry.register(new Scheme("https", (trustAll ? new FakeSocketFactory() : SSLSocketFactory.getSocketFactory()), 443)); client = new DefaultHttpClient(new ThreadSafeClientConnManager(httpParams, registry), httpParams); I make use of a FakeSocketFactory and FakeTrustManager, of which the source can be found here: http://code.google.com/p/transdroid/source/browse/#svn/trunk/src/org/transdroid/util Again, I don't understand why it suddenly stopped work, or even what the error 'Broken pipe' means. I have seen messages on Twitter that Seesmic and Twidroid fail with SSL enabled on FroYo as well, but am unsure if it's related. Thanks for any directions/help!

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• HELP!!! Upgrading to windows 2008 R2 server has caused major issue with screen scraping remote serve

  - by bobsov534

  I have three servers. One is Windows 2003(A) and another is Windows 2008(B) and third one is also Windows 2008 (C). All of them are web servers. A and B contains classic asp pages and they are 32 bit servers and C contains asp.net pages and is 64 bit server. The asp pages of A and B use the screen scraping technology to render the asp.net pages from C. When A is ran, the asp.net page is rendered fine, meaning there are no broken images or file not found error. When B is ran, the images appears to be broken because its looking for those images in Server B instead of Server C itself. I believe this issue is caused by IIS 7 or 7.5 since IIS 6 has no problem scraping the remote server pages. Can you please help me with solution to this problem? This is sort of urgent since upgrading to windows server 2008 R2 now has been a major show stopper for us at the moment. Thanks in advance.

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• [Perl] Testing for EAGAIN / EWOULDBLOCK on a recv

  - by Robert S. Barnes

  I'm testing a socket to see if it's still open: my $dummy = ''; my $ret = recv($sock, $dummy, 1, MSG_DONTWAIT | MSG_PEEK); if (!defined $ret || (length($dummy) == 0 && $! != EAGAIN && $! != EWOULDBLOCK )) { logerr("Broken pipe? ".__LINE__." $!"); } else { # socket still connected, reuse logerr(__LINE__.": $!"); return $sock; } I'm passing this code a socket I know for certain is open and it's always going through the first branch and logging "Broken pipe? 149 Resource temporarily unavailable". I don't understand how this is happening since "Resource temporarily unavailable" is supposed to correspond to EAGAIN as far as I know. I'm sure there must be something simple I'm missing. And yes, I know this is not a full proof way to test and I account for that.

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• EPIPE blocks server

  - by timn

  I have written a single-threaded asynchronous server in C running on Linux: The socket is non-blocking and as for polling, I am using epoll. Benchmarks show that the server performs fine and according to Valgrind, there are no memory leaks or other problems. The only problem is that when a write() command is interrupted (because the client closed the connection), the server will encounter a SIGPIPE. I am doing the interrupted artifically by running the benchmarking utility "siege" with the parameter -b. It does lots of requests in a row which all work perfectly. Now I press CTRL-C and restart the "siege". Sometimes I am lucky and the server does not manage to send the full response because the client's fd is invalid. As expected errno is set to EPIPE. I handle this situation, execute close() on the fd and then free the memory related to the connection. Now the problem is that the server blocks and does not answer properly anymore. Here is the strace output: accept(3, {sa_family=AF_INET, sin_port=htons(50611), sin_addr=inet_addr("127.0.0.1")}, [16]) = 5 fcntl64(5, F_GETFD) = 0 fcntl64(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 epoll_ctl(4, EPOLL_CTL_ADD, 5, {EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLET, {u32=158310248, u64=158310248}}) = 0 epoll_wait(4, {{EPOLLIN, {u32=158310248, u64=158310248}}}, 128, -1) = 1 read(5, "GET /user/register HTTP/1.1\r\nHos"..., 4096) = 161 write(5, "HTTP/1.1 200 OK\r\nContent-Type: t"..., 106) = 106 <<<<< write(5, "00001000\r\n", 10) = -1 EPIPE (Broken pipe) <<<<< Why did the previous write() work fine but not this one? --- SIGPIPE (Broken pipe) @ 0 (0) --- As you can see, the client establishes a new connection which consequently is accepted. Then, it's added to the EPOLL queue. epoll_wait() signalises that the client sent data (EPOLLIN). The request is parsed and and a response is composed. Sending the headers works fine but when it comes to the body, write() results in an EPIPE. It is not a bug in "siege" because it blocks any incoming connections, no matter from which client.

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• Why is it assumed that send may return with less than requested data transmitted on a blocking socke

  - by Ernelli

  The standard method to send data on a stream socket has always been to call send with a chunk of data to write, check the return value to see if all data was sent and then keep calling send again until the whole message has been accepted. For example this is a simple example of a common scheme: int send_all(int sock, unsigned char *buffer, int len) { int nsent; while(len 0) { nsent = send(sock, buffer, len, 0); if(nsent == -1) // error return -1; buffer += nsent; len -= nsent; } return 0; // ok, all data sent } Even the BSD manpage mentions that ...If no messages space is available at the socket to hold the message to be transmitted, then send() normally blocks... Which indicates that we should assume that send may return without sending all data. Now I find this rather broken but even W. Richard Stevens assumes this in his standard reference book about network programming, not in the beginning chapters, but the more advanced examples uses his own writen (write all data) function instead of calling write. Now I consider this still to be more or less broken, since if send is not able to transmit all data or accept the data in the underlying buffer and the socket is blocking, then send should block and return when the whole send request has been accepted. I mean, in the code example above, what will happen if send returns with less data sent is that it will be called right again with a new request. What has changed since last call? At max a few hundred CPU cycles have passed so the buffer is still full. If send now accepts the data why could'nt it accept it before? Otherwise we will end upp with an inefficient loop where we are trying to send data on a socket that cannot accept data and keep trying, or else? So it seems like the workaround, if needed, results in heavily inefficient code and in those circumstances blocking sockets should be avoided at all an non blocking sockets together with select should be used instead.

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• Google maps not showing satellite background - streets on white background.

  - by WooYek

  Custom map is broken on satellite view, does not show satellite imagery. Any ideas, what's wrong? Overlays are also broken - they're not transparent. Code: <div id="map_canvas" class="grid_8 omega" style="width:460px; height: 420px"></div> <script src="http://maps.google.com/maps?file=api&amp;v=3&amp;sensor=true&amp;key=my-key-is-here" type="text/javascript"></script> <script type="text/javascript"> function initialize() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map_canvas")); map.setCenter(new GLatLng(52.229676, 21.012229), 13); map.setMapType(G_HYBRID_MAP); map.setUIToDefault(); } var geocoder = new GClientGeocoder(); function showAddress(address) { geocoder.getLatLng(address, function(point) { if (!point) { alert('Nie mozna znalezc adresu: '+address); } else { map.setCenter(point, 13); var marker = new GMarker(point); map.addOverlay(marker); marker.openInfoWindowHtml(address); } } ); } showAddress('some address goes here') } $('body').ready(initialize); $('body').unload(GUnload); </script>

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• SQL Server Blocking Issue

  - by Robin Weston

  We currently have an issue that occurs roughly once a day on SQL 2005 database server, although the time it happens is not consistent. Basically, the database grinds to a halt, and starts refusing connections with the following error message. This includes logging into SSMS: A connection was successfully established with the server, but then an error occurred during the login process. (provider: TCP Provider, error: 0 - The specified network name is no longer available.) Our CPU usage for SQL is usually around 15%, but when the DB is in it's broken state it's around 70%, so it's clearly doing something, even if no-one can connect. Even if I disable the web app that uses the database the CPU still doesn't go down. I am unable to restart the SQLSERVER process as it is unresponsive, so I have to end up killing the process manually, which then puts the DB into Suspect/Recovery mode (which I can fix but it's a pain). Below are some PerfMon stats I gathered when the DB was in it's broken state which might help. I have a bunch more if people want to request them: Active Transactions: 2 (Never Changes) Logical Connections: 34 (NC) Process Blocked: 16 (NC) User Connections: 30 (NC) Batch Request: 0 (NC) Active Jobs: 2 (NC) Log Truncations: 596 (NC) Log Shrinks: 24 (NC) Longest Running Transaction Time: 99 (NC) I guess they key is finding out what the DB is using it's CPU on, but as I can't even log into SSMS this isn't possible with the standard methods. Disturbingly, I can't even use the dedicated admin connection to get into SSMS. I get the same timout as with all other requests. Any advice, reccomendations, or even sympathy, is much appreciated!

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• TFS 2010 Build gives WorkItemStore error when Create Work Item on Failure is enabled

  - by Derek Morrison

  I'm using TFS 2010 Build. I have a build definition that uses the DefaultTemplate.xaml template that's stock in TFS 2010, and the Create Work Item on Failure property is set to True in the build definition. I deliberately made a change in my project that breaks the build. When the build runs, I see the compilation error reflected in the TFS Build log within Visual Studio, but I get the error "Value cannot be null. Parameter name: WorkItemStore" when TFS Build next tries to generate a Work Item for the broken build. I tracked down the activity in DefaultTemplate.xaml (see the rather lengthy path to it below) where the Work Item is created for a broken build, and I see it uses the Microsoft.TeamFoundation.Build.Workflow.Activities.OpenWorkItem class to create the Work Item. The appropriate values seemed to be filled out in the Properties window for the Create Work Item activity, so I don't see where I can pass WorkItemStore to it and I don't even know appropriate values for this setting. Path to the Create Work Item activity: Process Sequence Run On Agent Try Compile, Test, and Associate Changesets and Work Items Sequence Compile, Test, and Associate Changesets and Work Items Try Compile and Test Compile and Test For Each Configuration in BuildSettings.PlatformConfigurations Compile and Test for Configuration If BuildSettings.HasProjectsToBuild For Each Project in BuildSettings.ProjectsToBuild Try to Compile the Project Handle Exception If CreateWorkItem Create Work Item for non-Shelveset Builds Create Work Item

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• HTTP: can GET and POST requests from a same machine come from different IPs?

  - by NoozNooz42

  I'm pretty sure I remember reading --but cannot find back the links anymore-- about this: on some ISP (including at least one big ISP in the U.S.) it is possible to have a user's GET and POST request appearing to come from different IPs. (note that this is totally programming related, and I'll give an example below) I'm not talking about having your IP adress dynamically change between two requests. I'm talking about this: IP 1: 123.45.67.89 IP 2: 101.22.33.44 The same user makes a GET, then a POST, then a GET again, then a POST again and the servers see this: - GET from IP 1 - POST from IP 2 - GET from IP 1 - POST from IP 2 So altough it's the same user, the webserver sees different IPs for the GET and the POSTs. Surely seen that HTTP is a stateless protocol this is perfectly legit right? I'd like to find back the explanation as to how/why certain ISP have their networks configured such that this may happen. I'm asking because someone asked me to implement the following IP filter and I'm pretty sure it is fundamentally broken code (breaking havoc for at least one major american ISP users). Here's a Java servlet filter that is supposed to protect against some attacks. The reasoning is that: "For any session filter checks that IP address in the request is the same that was used when session was created. So in this case session ID could not be stolen for forming fake sessions." http://www.servletsuite.com/servlets/protectsessionsflt.htm However I'm pretty sure this is inherently broken because there are ISPs where you may see GET and POST coming from different IPs. Any info on this subject is very welcome.

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• Problem with Restlet on GAE

  - by Leaf

  I'm trying to implement a calculator web service on GAE using Java Restlets... it works perfectly fine on localhost but when I upload my project to the Google App Engine everytime I try the web service link it says the link is broken. Here's the code I used: public Restlet createInboundRoot() { // Create a router Restlet that routes each call to a // new instance of HelloWorldResource. Router router = new Router(getContext()); Restlet restlet = new Restlet() { public void handle(Request request, Response response) { // Print the requested URI path String parameters = request.getResourceRef().getRemainingPart(); String message; if(parameters.charAt(0)=='?'){ message = "" + Calculator.calculate(parameters.substring(1)); } else { message = ""; } response.setEntity(message, MediaType.TEXT_PLAIN); } }; // Defines only one route router.attachDefault(restlet); return router; } The Application it's on is mapped to the /calcservice but as I said when I upload to GAE it comes back with a broken link error. I'm developing on Eclipse 3.4 and I'm wondering if there are any parameters I have to change to include the Restlet classes.

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