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• No Wireless Networks, BCM4313 [duplicate]

  - by TalonPlz

  This question already has an answer here: How to Install Broadcom Wireless Drivers (BCM43xx) 38 answers Just bought this little Asus 10 inch laptop that came with Ubuntu 12.04. Everything at my home was fine: Wireless identified and connected. As soon as I went to my girlfriend's house the trouble started. I couldn't connect to wireless (authentication... times out and asks for authentication) I started doing internet searching, tried a few solutions posted on line using terminal commands. No solutions. I decided to upgraded to 12.10-13.04 and that left me with a worse problem: I can no longer see ANY networks what so ever. Wireless card is ON, with out a doubt. Wired connection works. I have been fumbling with driver versions to no .avail, and have no idea which driver I am currently running I have a vague idea of what terminal lines to run: lshw: resources: irq:17 memory:f7d00000-f7dfffff *-network description: Wireless interface product: BCM4313 802.11b/g/n Wireless LAN Controller vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:02:00.0 logical name: eth2 version: 01 serial: dc:85:de:56:c4:ea width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=wl0 driverversion=6.20.155.1 (r326264) latency=0 multicast=yes wireless=IEEE 802.11abg resources: irq:17 memory:f7d00000-f7d03fff iwconfig: eth1 no wireless extensions. eth2 IEEE 802.11abg ESSID:off/any Mode:Managed Access Point: Not-Associated Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off lo no wireless extensions. I am new and excited to start my Ubuntu and Linux life and this is only the first of my few hic cups i am sure! :) Thanks all UPDATE: Report from 2nd answer talon@Black1015E:~$ sudo apt-get remove --purge bcmwl-kernel-source [sudo] password for talon: Reading package lists... Done Building dependency tree Reading state information... Done Package 'bcmwl-kernel-source' is not installed, so not removed 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. talon@Black1015E:~$ wget http://us.archive.ubuntu.com/ubuntu/pool/restricted/b/bcmwl/bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb --2013-10-22 18:50:32-- http://us.archive.ubuntu.com/ubuntu/pool/restricted/b/bcmwl/bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb Resolving us.archive.ubuntu.com (us.archive.ubuntu.com)... 2001:67c:1562::15, 2001:67c:1562::13, 2001:67c:1562::14, ... Connecting to us.archive.ubuntu.com (us.archive.ubuntu.com)|2001:67c:1562::15|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 1181334 (1.1M) [application/x-debian-package] Saving to: ‘bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb’ 100%[======================================>] 1,181,334 3.37MB/s in 0.3s 2013-10-22 18:50:33 (3.37 MB/s) - ‘bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb’ saved [1181334/1181334] talon@Black1015E:~$ arvh No command 'arvh' found, did you mean: Command 'arch' from package 'coreutils' (main) arvh: command not found talon@Black1015E:~$ arch x86_64 talon@Black1015E:~$ sudo dpkg -i bcmwl*.deb Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 171895 files and directories currently installed.) Unpacking bcmwl-kernel-source (from bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb) ... Setting up bcmwl-kernel-source (5.100.82.112+bdcom-0ubuntu3) ... Loading new bcmwl-5.100.82.112+bdcom DKMS files... First Installation: checking all kernels... Building only for 3.8.0-32-generic Building for architecture x86_64 Building initial module for 3.8.0-32-generic Done. wl: Running module version sanity check. - Original module - No original module exists within this kernel - Installation - Installing to /lib/modules/3.8.0-32-generic/updates/dkms/ depmod........ DKMS: install completed. Error: Module b43 is not currently loaded Error: Module b43legacy is not currently loaded Error: Module ssb is not currently loaded Error: Module bcm43xx is not currently loaded Error: Module brcm80211 is not currently loaded Error: Module brcmfmac is not currently loaded update-initramfs: deferring update (trigger activated) Processing triggers for initramfs-tools ... update-initramfs: Generating /boot/initrd.img-3.8.0-32-generic rebooting now

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• Intermittent internet connectivity

  - by Rob Oplawar

  UPDATED: I recently built a new computer and set it up to dual-boot Windows 7 and Ubuntu 11.10. In Windows, using the same hardware, my LAN connectivity is solid. In Ubuntu, however, my network interface periodically dies and resets itself; I'll have a solid connection for 30 seconds, and then it will go out for 30 seconds. When I tail the log: tail -f /var/log/kern.log I see "eth0 link up" messages appear periodically, corresponding with the return of connectivity. I posted the original question months ago, and misinterpreted what was going on. With a working Internet connection in Windows, I ignored the problem for some months. See my answer below for the solution (drivers). ORIGINAL POST In Ubuntu, although I maintain a solid connection to my LAN (pinging the router IP address consistently returns a good result), my internet connectivity drops in and out. When I continuously ping 74.125.227.18 (a google.com server), I get responses for a while, then I start getting "Destination Host Unreachable" for a while, then I get responses again. This happens consistently, dropping the connection for about 30 seconds out of every minute or two. Whether I configure my network via the network manager or via /etc/network/interfaces seems to make no difference. I configure with the following settings: address 192.168.1.101 network 192.168.1.0 gateway 192.168.1.99 (my router's IP address) netmask 255.255.255.0 (confirmed as the right netmask for the router) broadcast 192.168.1.255 (also confirmed with the router). ifconfig confirms that these settings are working: eth0 Link encap:Ethernet HWaddr 50:e5:49:40:da:a6 inet addr:192.168.1.101 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::52e5:49ff:fe40:daa6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:11557 errors:0 dropped:11557 overruns:0 frame:11557 TX packets:13117 errors:0 dropped:211 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:9551488 (9.5 MB) TX bytes:1930952 (1.9 MB) Interrupt:41 Base address:0xa000 I get the same issue when I use automatic DHCP address settings, although I did confirm that there is no other machine on the network with the static IP address I want to use. As I said, the connection to the local network stays solid - I never have any trouble pinging 192.168.1.* - it's internet addresses that I intermittently cannot reach. It's not a DNS issue because pinging known IP addresses directly shows the same behavior. Also, I don't think it's a hardware issue, as I never have any internet connectivity problems on the same machine in Windows. The network hardware is built into the motherboard: Gigabyte Z68XP-UD3P. I managed to bring the OS fully up to date, according to the update manager, but it didn't fix the issue, and with my limited understanding of network architecture I'm at my wit's end. The only clue I can see is that ifconfig is reporting a lot of dropped packets, but I'm not sure what to do about it. UPDATE: It seems my problem is a little more generic than I described; now when I try pinging my router and google simultaneously, they both go unreachable at the same time. Running ifdown eth0 and then ifup eth0 brings it back temporarily; if I just wait it comes back after a couple of minutes. I'll broaden my search through intermittent network connectivity problems.

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• Errors when switching to specific static IP

  - by michaelc

  I had a Fedora box running using my static IP 69.169.136.6, etc, all configured according to what the ISP required. Just recently the hard drive failed (and I should have been keeping better backups) - while it is being recovered I would like to put up a webpage on my Archlinux PC explaining the problem - I presently do not have sufficient access to change the DNS record assigned to the domain. When I change my ip address while my system is running to 69.169.136.6, ifconfig reports the new ip address, but http://whatismyip.com/ does not. When I change it and reboot, I can't ping - the message I recieve is "connect: Network is unreachable" (when given one of google.com 's IP addresses - hostnames give me ping: unknown host xxx). Until I have access to the DNS system, what can I do to make this work? Edit: With new IP address, same problem, IP is now 69.169.136.29. Some commands might be useful: #ping 69.169.136.1 PING 69.169.136.1 (69.169.136.1) 56(84) bytes of data. 64 bytes from 69.169.136.1: icmp_seq=1 ttl=64 time=0.377 ms #ping 69.169.190.211 connect: Network is unreachable #ping 208.72.160.67 connect: Network is unreachable #ifconfig eth0 Link encap:Ethernet HWaddr 00:E0:4D:97:23:9B inet addr:69.169.136.29 Bcast:69.169.137.255 Mask:255.255.254.0 inet6 addr: fe80::2e0:4dff:fe97:239b/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:132091 errors:0 dropped:0 overruns:0 frame:0 TX packets:17 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:9635179 (9.1 Mb) TX bytes:1322 (1.2 Kb) Interrupt:29 Base address:0x6000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:48 errors:0 dropped:0 overruns:0 frame:0 TX packets:48 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2480 (2.4 Kb) TX bytes:2480 (2.4 Kb) #ip route 69.169.136.0/23 dev eth0 proto kernel scope link src 69.169.136.29 #cat /etc/resolv.conf # Generated by dhcpcd #nameserver 208.67.222.222 #nameserver 208.67.220.220 nameserver 69.169.190.211 nameserver 208.72.160.67 # /etc/resolv.conf.tail can replace this line Update: have new static IP addresses, verified to work in Windows... Relevant portions of /etc/rc.conf below: #Static IP example #eth0="eth0 69.169.136.6 netmask 255.255.254.0 broadcast 69.169.136.1" #eth0="eth0 69.169.136.29 netmask 255.255.254.0 broadcast 69.169.137.255" eth0="eth0 69.169.136.32 netmask 255.255.254.0 broadcast 69.169.137.255" #eth0="dhcp" INTERFACES=(eth0) # Routes to start at boot-up (in this order) # Declare each route then list in ROUTES # - prefix an entry in ROUTES with a ! to disable it # #gateway="default gw 192.168.0.1" gateway="default gw 69.169.136.1" #gateway="69.169.136.1" ROUTES=(!gateway) #ROUTES=()

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• Linux Mint Wireless doesn't connect

  - by guisantogui

  I'm having a great problem, I've installed Linux mint debian edition (LMDE), and following this tutorial http://community.linuxmint.com/tutorial/view/161 I did installed the network driver. The available connections appears to me, but when i try to connect to my connection at first time, I got this message: "(4) Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken." And the following tries, I got this another message: "(32) Insufficient privileges." I'm accepting ideas. Thanks. EDIT: The last piece of the logs: Oct 5 00:22:38 gsouza-host ntpd[2116]: peers refreshed Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> (wlan0): bringing up device. Oct 5 00:22:42 gsouza-host wpa_supplicant[2055]: nl80211: 'nl80211' generic netlink not found Oct 5 00:22:42 gsouza-host wpa_supplicant[2055]: Failed to initialize driver 'nl80211' Oct 5 00:22:42 gsouza-host wpa_supplicant[2055]: rfkill: WLAN soft blocked Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> WiFi hardware radio set enabled Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> WiFi now enabled by radio killswitch Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> (wlan0): supplicant interface state: starting -> ready Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> (wlan0): device state change: unavailable -> disconnected (reason 'supplicant-available') [20 30 42] Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <info> (wlan0): supplicant interface state: ready -> inactive Oct 5 00:22:42 gsouza-host NetworkManager[2019]: <warn> Trying to remove a non-existant call id. Oct 5 00:22:42 gsouza-host wpa_supplicant[2055]: rfkill: WLAN unblocked Oct 5 00:22:44 gsouza-host avahi-daemon[1827]: Joining mDNS multicast group on interface wlan0.IPv6 with address fe80::7ae4:ff:fe4a:13a9. Oct 5 00:22:44 gsouza-host avahi-daemon[1827]: New relevant interface wlan0.IPv6 for mDNS. Oct 5 00:22:44 gsouza-host avahi-daemon[1827]: Registering new address record for fe80::7ae4:ff:fe4a:13a9 on wlan0.*. Oct 5 00:22:46 gsouza-host ntpd[2116]: Listen normally on 7 wlan0 fe80::7ae4:ff:fe4a:13a9 UDP 123 Oct 5 00:22:46 gsouza-host ntpd[2116]: peers refreshed

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• Gateway on a virtual network interface used by LXC guests

  - by linkdd

  I'm currently having some problems with configuring a gateway for a virtual network interface. Here is what I've done : I created a virtual network interface : # brctl addbr lxc0 # brctl setfd lxc0 0 # ifconfig lxc0 192.168.0.1 promisc up # route add -net default gw 192.168.0.1 lxc0 The output of ifconfig gave me what I wanted : lxc0 Link encap:Ethernet HWaddr 22:4f:e4:40:89:bb inet adr:192.168.0.1 Bcast:192.168.0.255 Masque:255.255.255.0 adr inet6: fe80::88cf:d4ff:fe47:3b6b/64 Scope:Lien UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:623 errors:0 dropped:0 overruns:0 frame:0 TX packets:7412 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:50329 (49.1 KiB) TX bytes:335738 (327.8 KiB) I configured dnsmasq to provide a DNS server (using the default : 192.168.1.1) and a DHCP server. Then, my LXC guest is configured like this : lxc.network.type=veth lxc.network.link=lxc0 lxc.network.flags=up Every thing is working perfectly, my containers have an IP (192.168.0.57 and 192.168.0.98). I can ping the host and the containers from the containers and from the host : (host)# ping -c 3 192.168.0.114 PING 192.168.0.114 (192.168.0.114) 56(84) bytes of data. 64 bytes from 192.168.0.114: icmp_req=1 ttl=64 time=0.044 ms 64 bytes from 192.168.0.114: icmp_req=2 ttl=64 time=0.038 ms 64 bytes from 192.168.0.114: icmp_req=3 ttl=64 time=0.043 ms --- 192.168.0.114 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 1998ms rtt min/avg/max/mdev = 0.038/0.041/0.044/0.007 ms (guest)# ping -c 3 192.168.0.1 PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data. 64 bytes from 192.168.0.1: icmp_req=1 ttl=64 time=0.048 ms 64 bytes from 192.168.0.1: icmp_req=2 ttl=64 time=0.042 ms 64 bytes from 192.168.0.1: icmp_req=3 ttl=64 time=0.042 ms --- 192.168.0.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 1999ms rtt min/avg/max/mdev = 0.042/0.044/0.048/0.003 ms Now, it's time to configure the host as a gateway for the network 192.168.0.0/24 : #!/bin/sh # Clear rules iptables -F iptables -t nat -F iptables -t mangle -F iptables -X iptables -A FORWARD -i lxc0 -o eth0 -j ACCEPT iptables -A FORWARD -i eth0 -o lxc0 -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE echo 1 > /proc/sys/net/ipv4/ip_forward The final test failed completely, ping the outside : (guest)# ping -c 3 google.fr PING google.fr (173.194.67.94) 56(84) bytes of data. From 192.168.0.1: icmp_seq=3 Redirect Host(New nexthop: wi-in-f94.1e100.net (173.194.67.94)) From 192.168.0.1 icmp_seq=1 Destination Host Unreachable From 192.168.0.1 icmp_seq=2 Destination Host Unreachable From 192.168.0.1 icmp_seq=3 Destination Host Unreachable --- google.fr ping statistics --- 3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2017ms Did I missed something ?

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• Cliq Wireless questions

  - by Nathan Adams

  Heres the deal: I am by no means a Linux expert, even less when it comes to the Android OS but lets see if we can't solve this problem. The problem I am having is that on the Cliq we have a broadcom chip. In order to use the wireless card you must first insert the module into the kernel. Fine: # insmod /system/lib/dhd.ko insmod /system/lib/dhd.ko # lsmod lsmod dhd 164936 0 - Live 0xbf000000 # BUT netcfg (or ifconfig in busybox) does not recognize that there is a wireless adapter there: # netcfg netcfg lo UP 127.0.0.1 255.0.0.0 0x00000049 dummy0 DOWN 0.0.0.0 0.0.0.0 0x00000082 rmnet0 UP 14.67.164.2 255.255.255.252 0x00001043 rmnet1 DOWN 0.0.0.0 0.0.0.0 0x00001002 rmnet2 DOWN 0.0.0.0 0.0.0.0 0x00001002 usb0 DOWN 0.0.0.0 0.0.0.0 0x00001002 # busybox ifconfig busybox ifconfig lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:282 errors:0 dropped:0 overruns:0 frame:0 TX packets:282 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:18754 (18.3 KiB) TX bytes:18754 (18.3 KiB) rmnet0 Link encap:Ethernet HWaddr EE:83:E8:B4:4A:ED inet addr:14.x.x.x Bcast:14.67.164.3 Mask:255.255.255.252 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:7148 errors:0 dropped:0 overruns:0 frame:0 TX packets:7659 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2609236 (2.4 MiB) TX bytes:908575 (887.2 KiB) # For giggles if we attempt to launch wpa_supplicant anyways we get this: # wpa_supplicant -Dwext -ieth0 -c/data/misc/wifi/wpa_supplicant.conf wpa_supplicant -Dwext -ieth0 -c/data/misc/wifi/wpa_supplicant.conf ioctl[SIOCSIWPMKSA]: No such device ioctl[SIOCSIWMODE]: No such device Could not configure driver to use managed mode ioctl[SIOCGIFFLAGS]: No such device Could not set interface 'eth0' UP ioctl[SIOCGIWRANGE]: No such device ioctl[SIOCGIFINDEX]: No such device CTRL-EVENT-STATE-CHANGE id=-1 state=0 ioctl[SIOCSIWENCODEEXT]: No such device ioctl[SIOCSIWENCODE]: No such device ioctl[SIOCSIWENCODEEXT]: No such device ioctl[SIOCSIWENCODE]: No such device ioctl[SIOCSIWENCODEEXT]: No such device ioctl[SIOCSIWENCODE]: No such device ioctl[SIOCSIWENCODEEXT]: No such device ioctl[SIOCSIWENCODE]: No such device ioctl[SIOCSIWAUTH]: No such device WEXT auth param 7 value 0x0 - Failed to disable WPA in the driver. ioctl[SIOCSIWAUTH]: No such device WEXT auth param 5 value 0x0 - ioctl[SIOCSIWAUTH]: No such device WEXT auth param 4 value 0x0 - ioctl[SIOCSIWAP]: No such device ioctl[SIOCGIFFLAGS]: No such device # In dmesg we get: <4>[18300.494065] dhd_oob_enable_intr : enable <4>[18305.019976] dhd_net_start failed bus is not ready <4>[18305.020278] dhdsdio_probe: dhd_net_start failed! Do I need to specify the firmware with insmod? Why are we trying to control the interface manually instead of through the Android API? The Android API doesn't support ad-hoc connections as far as I can tell. The card, I am sure, most certainly can.

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• Mysql server fails to start

  - by Nicolas Thery

  Googling since two hours, I require your assistance. I'm on a Debian virtual machine and I cloned it. The only change is the new IP adress it has. Mysql doesn't start any more: Starting MySQL database server: mysqld . . . . . . . . . . . . . . failed! There is no process called mysql. All the mysql log files in /var/log are empty. here is my.cnf file : [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking bind-address = 127.0.0.1 key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam-recover = BACKUP query_cache_limit = 1M query_cache_size = 16M general_log_file = /var/log/mysql/mysql.log log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] [isamchk] key_buffer = 16M [mysqld_safe] syslog Here is the result of ifconfig : eth0 Link encap:Ethernet HWaddr 00:0c:29:12:98:9a inet adr:192.168.1.138 Bcast:192.168.1.255 Masque:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:754 errors:0 dropped:0 overruns:0 frame:0 TX packets:106 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:1000 RX bytes:101177 (98.8 KiB) TX bytes:17719 (17.3 KiB) lo Link encap:Boucle locale inet adr:127.0.0.1 Masque:255.0.0.0 adr inet6: ::1/128 Scope:Hôte UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:560 (560.0 B) TX bytes:560 (560.0 B) As requested, here is the result of : sudo -u mysql mysqld, here is the result : root@debian:/home/nicolas/Bureau# sudo -u mysql mysqld 121004 14:26:57 [Note] Plugin 'FEDERATED' is disabled. mysqld: Can't find file: './mysql/plugin.frm' (errno: 13) 121004 14:26:57 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. 121004 14:26:57 InnoDB: Initializing buffer pool, size = 8.0M 121004 14:26:57 InnoDB: Completed initialization of buffer pool 121004 14:26:57 InnoDB: Started; log sequence number 0 70822697 121004 14:26:57 [Note] Recovering after a crash using /var/log/mysql/mysql-bin 121004 14:26:57 [Note] Starting crash recovery... 121004 14:26:57 [Note] Crash recovery finished. 121004 14:26:57 [ERROR] mysqld: Can't find file: './mysql/host.frm' (errno: 13) 121004 14:26:57 [ERROR] Fatal error: Can't open and lock privilege tables: Can't find file: './mysql/host.frm' (errno: 13)

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• Connecting to localhost resolves 127.0.0.1 but connects with external IP [Linux, Debian]

  - by skgsergio

  I'm having a problem with a dedicated server, I don't known if it's the default behavior but this is the problem: If I connect to a service located on the server with localhost the service gets as source IP the external IP. Let me show an example, I use netcat for listening on 127.0.0.1:4444 xxxxxx # nc -vv -l -s 127.0.0.1 -p 4444 listening on [127.0.0.1] 4444 ... Lets check if it's ok: xxxxxx ~ # netstat -atnp | grep 4444 tcp 0 0 127.0.0.1:4444 0.0.0.0:* LISTEN 14038/nc Ok lets connect: xxxxxx ~ # nc -vv 127.0.0.1 4444 localhost [127.0.0.1] 4444 (?) open Return to the tty that have the listening process and I get this: connect to [127.0.0.1] from xxxxxx.net [176.31.xxx.xx] 50354 So that's the problem. I have a server daemon that have to listen on localhost and checks that the ip is 127.0.0.1 when the client connects but for some reason when I connect to localhost it reports the external ip... If I do the same with IPv6 it works as excepted... Detects connection as localhost (::1). Some info that can be useful: "localhost" resolves without problems to 127.0.0.1 xxxxxx ~ # ping -c1 localhost PING localhost (127.0.0.1) 56(84) bytes of data. 64 bytes from localhost (127.0.0.1): icmp_req=1 ttl=64 time=0.086 ms Nothing weird on my hosts file, I think... xxxxxx ~ # grep -v ^# /etc/hosts 127.0.0.1 localhost localhost.localdomain 176.31.xxx.xx xxxxxx.net ns1.xxxxxx.net ::1 ip6-localhost ip6-loopback feo0::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts And ifconfig reports all ok... eth0 Link encap:Ethernet HWaddr e0:69:95:d8:30:a1 inet addr:176.31.xxx.xx Bcast:176.31.108.255 Mask:255.255.255.0 inet6 addr: 2001:41d0:8:xxxx::/64 Scope:Global inet6 addr: 2001:41d0:8:xxxx:x:xx:xx:xx/64 Scope:Global inet6 addr: fe80::e269:95ff:fed8:30a1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:16916 errors:0 dropped:0 overruns:0 frame:0 TX packets:16914 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:8410679 (8.0 MiB) TX bytes:10539881 (10.0 MiB) Interrupt:28 Base address:0xe000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:5570 errors:0 dropped:0 overruns:0 frame:0 TX packets:5570 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:744490 (727.0 KiB) TX bytes:744490 (727.0 KiB)

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• ubuntu eth0 not reconnecting after cable unplugged

  - by Alex

  I'm running kubuntu 9.10 w/ gnome, I have a static IP defined in /etc/network/interfaces When I unplugged my network cable and rebooted, then reconnected the network cable I was not able to connect. I tried using sudo ifup eth0, and then ifconfig and it seemed as though the IP address had been assigned and I was connected, but I wasn't. I then did ifdown eth0, and again ifup eth0. For some reason I'm not able to access the network. Furthermore, I also attempted to connect via wlan, and was able to connect to the wireless network, but cannot "see" the network. I can't transfer data or access the internet or anything on the network including the router. How do I resolve this? topsy@monolyth:~$ ifconfig eth0 Link encap:Ethernet HWaddr 00:1c:25:1c:df:70 inet addr:192.168.1.145 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::21c:25ff:fe1c:df70/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5720 errors:0 dropped:0 overruns:0 frame:0 TX packets:565 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:378035 (378.0 KB) TX bytes:46832 (46.8 KB) Memory:fe000000-fe020000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:4 errors:0 dropped:0 overruns:0 frame:0 TX packets:4 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:240 (240.0 B) TX bytes:240 (240.0 B) By access the network I mean the local network as well as the internet. topsy@monolyth:~$ ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=9.14 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.24 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=1.01 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=1.00 ms [snip... all OK, icmp_seq from 5-30, time between 0.981-1.25ms] ^C --- 192.168.1.1 ping statistics --- 30 packets transmitted, 30 received, 0% packet loss, time 29035ms rtt min/avg/max/mdev = 0.971/1.300/9.140/1.458 ms topsy@monolyth:~$ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 * 255.255.255.0 U 0 0 0 eth0 link-local * 255.255.0.0 U 1000 0 0 eth0 default 192.168.1.1 0.0.0.0 UG 100 0 0 eth0 root@monolyth:~# cat /etc/resolv.conf # Generated by NetworkManager

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• Download - Upload is too slow on Centos

  - by Mehdi

  My download/upload in server and out of server is too slow (around 50 KB/s !) ! Did I miss some configuration ? Some information: CentOS release 6.3 uptime load average: 0.17, 0.32, 0.37 Memory free -m total used free shared buffers cached Mem: 24009 21988 2021 0 806 18098 -/+ buffers/cache: 3083 20926 Swap: 4095 28 4067 lshw -C network *-network description: Ethernet interface product: 82574L Gigabit Network Connection vendor: Intel Corporation physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: 00 serial: 00:25:90:70:17:4a size: 100MB/s capacity: 1GB/s width: 32 bits clock: 33MHz capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=off broadcast=yes driver=e1000e driverversion=1.9.5-k duplex=full firmware=2.1-2 ip=108.175.8.123 latency=0 link=yes multicast=yes port=twisted pair speed=100MB/s resources: irq:16 memory:fb900000-fb91ffff ioport:e000(size=32) memory:fb920000-fb923fff ethtool ethtool eth0 Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: Not reported Advertised pause frame use: No Advertised auto-negotiation: No Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: off MDI-X: off Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000001 (1) Link detected: yes dmesg |grep e1000e dmesg |grep e1000e e1000e: Intel(R) PRO/1000 Network Driver - 1.9.5-k e1000e: Copyright(c) 1999 - 2012 Intel Corporation. e1000e 0000:02:00.0: Disabling ASPM L0s e1000e 0000:02:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 e1000e 0000:02:00.0: setting latency timer to 64 e1000e 0000:02:00.0: irq 33 for MSI/MSI-X e1000e 0000:02:00.0: irq 34 for MSI/MSI-X e1000e 0000:02:00.0: irq 35 for MSI/MSI-X e1000e 0000:02:00.0: eth0: (PCI Express:2.5GT/s:Width x1) 00:25:90:70:17:4a e1000e 0000:02:00.0: eth0: Intel(R) PRO/1000 Network Connection e1000e 0000:02:00.0: eth0: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e 0000:02:00.0: eth0: Unsupported Speed/Duplex configuration e1000e: eth0 NIC Link is Up 10 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e 0000:02:00.0: Disabling ASPM L1 e1000e 0000:02:00.0: eth0: changing MTU from 1500 to 9000 e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None e1000e 0000:02:00.0: eth0: 10/100 speed: disabling TSO

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• Ubuntu box static routing problem

  - by Rafael

  Hello, I'm trying to configure a ubuntu server to be a router. This is my interface configuration (eth2 connects to my WAN, eth0 to my LAN): auto eth2 iface eth2 inet static address 192.168.0.249 netmask 255.255.255.0 gateway 192.168.0.1 broadcast 192.168.0.255 auto eth0 iface eth0 inet static address 192.168.100.1 netmask 255.255.255.0 This is the router information: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2 0.0.0.0 192.168.0.1 0.0.0.0 UG 100 0 0 eth2 And this is dhcp configuration: subnet 192.168.100.0 netmask 255.255.255.0 { range 192.168.100.101 192.168.100.254; option domain-name-servers 201.70.86.133; option routers 192.168.100.1; authoritative; } I'm then connecting a mac os x by cable on eth0. This is en0 interface configuration: en0: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 ether 00:26:bb:5d:82:b0 inet6 fe80::226:bbff:fe5d:82b0%en0 prefixlen 64 scopeid 0x4 inet 192.168.100.101 netmask 0xffffff00 broadcast 192.168.100.255 media: autoselect (100baseTX <full-duplex>) status: active And this is the routing table: Internet: Destination Gateway Flags Refs Use Netif Expire default 192.168.100.1 UGSc 139 32 en0 10.37.129/24 link#8 UC 2 0 vnic1 10.37.129.2 0:1c:42:0:0:9 UHLWI 0 839 lo0 10.37.129.255 ff:ff:ff:ff:ff:ff UHLWbI 0 4 vnic1 10.211.55/24 link#7 UC 2 0 vnic0 10.211.55.2 0:1c:42:0:0:8 UHLWI 0 840 lo0 10.211.55.255 ff:ff:ff:ff:ff:ff UHLWbI 0 4 vnic0 127 127.0.0.1 UCS 0 0 lo0 127.0.0.1 127.0.0.1 UH 3 507924 lo0 169.254 link#4 UCS 0 0 en0 172.16.42/24 link#10 UC 2 0 vmnet8 172.16.42.1 0:50:56:c0:0:8 UHLWI 0 839 lo0 172.16.42.255 link#10 UHLWbI 1 24 vmnet8 192.168.100 link#4 UC 2 0 en0 192.168.100.1 0:e0:7c:7e:f:99 UHLWI 139 0 en0 777 192.168.100.101 127.0.0.1 UHS 0 0 lo0 192.168.100.255 ff:ff:ff:ff:ff:ff UHLWbI 0 4 en0 192.168.116 link#9 UC 2 0 vmnet1 192.168.116.1 0:50:56:c0:0:1 UHLWI 0 839 lo0 192.168.116.255 ff:ff:ff:ff:ff:ff UHLWbI 0 4 vmnet1 When I ping 192.168.100.1, it works. When I ping 192.168.0.249, it also works. However, when I try to ping 192.168.0.1 it does not. Does anyone has any way to solve this? Is there a way to debug it? Thanks,

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• How do I combine static and dynamic DHCP leases on a Cisco router?

  - by Brad

  Basically, what I need is super similar to the unanswered cisco forum question below: https://supportforums.cisco.com/message/3139749#3139749 I have a Cisco 850 Series router. I have configured a DHCP pool for the 10.0.0.0/24 network. I have excluded 10.0.0.1 - 10.0.0.99 from the DHCP pool. I want to add a static DHCP pool for stuff and I want DHCP to statically assign them the addresses of my choice below 100. Actually, I don't care what addresses I statically assign. They can be anything in the pool for all I care, I just want it to work. Why are you doing this? Just statically assign the IPs on the devices! I don't want to do this because I have some laptop users. They could obviously only use that static IP here. This isn't a problem if they could be bothered to change any location setting or something. They can't. So it HAS to be DHCP. It also has to be static IPs because I need to forward ports to them. I know, I know, this is weird but it's an apartment LAN/WLAN so this isn't exactly a typical use case. Relevant sections of config below: ip dhcp excluded-address 10.0.0.1 10.0.0.99 ! ip dhcp pool Internal-net import all network 10.0.0.0 255.255.255.0 default-router 10.0.0.1 domain-name 1770.local lease 7 ! ip dhcp pool static-pool import all origin file flash://staticmap default-router 10.0.0.1 domain-name 1770.local Contents of staticmap: *time* Aug 5 2010 09:00 AM *version* 2 !IP address Type Hardware address Lease expiration 10.0.0.100/24 1 001f.5b3e.d50a Infinite *end* You can see here I was trying addresses outside the excluded-address range to see if that would make any difference. My testing machine's MAC: mainframe:~ brad$ ifconfig en1 en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:1f:5b:3e:d5:0a What shows up in the DHCP binding table: basestar#show ip dhcp binding Bindings from all pools not associated with VRF: IP address Client-ID/ Lease expiration Type Hardware address/ User name 10.0.0.112 0100.1f5b.3ed5.0a Aug 12 2010 10:06 AM Automatic What's up with the funny looking MAC in the DHCP binding table?? Is what I'm trying to accomplish basically impossible? Am I going about this the wrong way? All I want to to be able to port forward some ports to specific devices. The way I would do this with a consumer router is to do what I'm trying to do here; assign static DHCP to those devices then configure PAT for ports on those addresses.

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• udp expected behaviour not responding to test result

  - by ernst

  I have a local network topology that is structured as follows: three hosts and a switch in the middle. I am using a switch that supports 10,100,1000 Mbit/s full/half duplex connection. I have configured the hosts with a static ip 172.16.0.1-2-3/25. This is the output of ifconfig eth0 Link encap: Ethernet HWaddr ***** inet addr:172.16.0.3 Bcast:172.16.0.127 Mask:255.255.255.128 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:16 The output on H1 and H2 is perfectly matchable They are mutually reachable since i have tested the network with ping. I have forced the ethernet interface to work at 10M with ethtool -s eth0 speed 10 duplex full autoneg on this is the output of ethtool eth0 supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full S upported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Full Advertised pause frame use: Symmetric A dvertised auto-negotiation: Yes Speed: 10Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on MDI-X: Unknown Supports Wake-on: g Wake-on: d Current message level: 0x000000ff (255) drv probe link timer ifdown ifup rx_err tx_err Link detected: yes – I am doing an experimental test using nttcp to calculate the GOODPUT in the case that H1 and H2 at the same time send data to H3. Since the three links have the same forced capability and the amount of arrving data speed is 10 from H1+10 from H2--20M to H3 it would be expected a bottleneck effect and, due to the non reliable nature of udp, a packet loss. But this doesn't appen since the output of nttcp application shows the same number of byte sended and received. this is the output of nttcp on h3 nttcp -T -r -u 172.16.0.2 & nttcp -T -r -u 172.16.0.1 [1] 4071 Bytes Real s CPU s Real-MBit/s CPU-MBit/s Calls Real-C/s CPU-C/s l 8388608 13.74 0.05 4.8848 1398.0140 2049 149.14 42684.8 Bytes Real s CPU s Real-MBit/s CPU-MBit/s Calls Real-C/s CPU-C/s l 8388608 14.02 0.05 4.7872 1398.0140 2049 146.17 42684.8 1 8388608 13.56 0.06 4.9500 1118.4065 2051 151.28 34181.1 1 8388608 13.89 0.06 4.8310 1198.3084 2051 147.65 36623.0 – How is this possible? Am i missing something? Any help will be gratefully apprecciated, Best regards

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• Network unreachable on Ubuntu guest after trying to set up a host only network on Virtualbox

  - by gkb0986

  I have a Mac OS X host and a bunch of guests including Ubuntu and Arch Linux. I was trying to set up a host-only network at eth1 to let me ssh into the system. But now eth0 isn't working properly either. Ubuntu can no longer connect to remote hosts or browse the internet. It tells me that the network is unreachable. What's gone wrong here? I've included some diagnostics below. $ifconfig lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:10968 errors:0 dropped:0 overruns:0 frame:0 TX packets:10968 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:897264 (897.2 KB) TX bytes:897264 (897.2 KB) Other diagnostic commands and the output: $sudo lspci -n 00:00.0 0600: 8086:1237 (rev 02) 00:01.0 0601: 8086:7000 00:01.1 0101: 8086:7111 (rev 01) 00:02.0 0300: 80ee:beef 00:03.0 0200: 8086:100e (rev 02) 00:04.0 0880: 80ee:cafe 00:05.0 0401: 8086:2415 (rev 01) 00:06.0 0C03: 106B:003F 00:07.0 0680: 8086:7113 (REV 08) 00:0D.0 0106: 8086:2829 (REV 02) $sudo lshw -c network *-network DISABLED description: Ethernet interface product: 82540EM Gigabit Ethernet Controller vendor: Intel Corporation physical id: 3 bus info: pci@0000:00:03.0 logical name: eth0 version: 02 serial: 08:00:27:7d:22:df size: 1Gbit/s capacity: 1Gbit/s width: 32 bits clock: 66MHz capabilities: pm pcix bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=e1000 driverversion=7.3.21-k8-NAPI duplex=full firmware=N/A latency=64 link=no mingnt=255 multicast=yes port=twisted pair speed=1Gbit/s resources: irq:19 memory:f0000000-f001ffff ioport:d010(size=8) $lsmod Module Size Used by nls_utf8 12557 1 isofs 40257 1 vboxsf 43743 2 vesafb 13844 1 snd_intel8x0 38570 2 snd_ac97_codec 134869 1 snd_intel8x0 ac97_bus 12730 1 snd_ac97_codec snd_pcm 97275 2 snd_intel8x0,snd_ac97_codec snd_seq_midi 13324 0 snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi rfcomm 47604 0 snd_seq 61929 2 snd_seq_midi,snd_seq_midi_event bnep 18281 2 bluetooth 180113 10 rfcomm,bnep ppdev 17113 0 psmouse 97519 0 snd_timer 29990 2 snd_pcm,snd_seq joydev 17693 0 snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq vboxvideo 12622 1 serio_raw 13211 0 snd 79041 11 snd_intel8x0,snd_ac97_codec,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device soundcore 15091 1 snd vboxguest 235498 7 vboxsf parport_pc 32866 0 drm 241971 2 vboxvideo i2c_piix4 13301 0 snd_page_alloc 18529 2 snd_intel8x0,snd_pcm mac_hid 13253 0 lp 17799 0 parport 46562 3 ppdev,parport_pc,lp usbhid 47238 0 hid 99636 1 usbhid e1000 108589 0

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• [CentOS 4.8] nslookup resolves domains to IPs, but I can't get a response to pings to external servers

  - by Beco

  I have a fresh install of CentOS 4.8 running on an internal development server. I haven't done anything to it besides setting up sudoers and SSH. I can SSH into the server and from there resolve domains to IPs and ping internal servers, but for some reason I don't get any response from pinging external servers. The software firewall is disabled, and the problem is present with both static and DHCP-assigned network configurations. The network domain controller is a Windows Server 2003 box. $ nslookup google.com Server: 10.254.2.5 Address: 10.254.2.5#53 Non-authoritative answer: Name: google.com Address: 74.125.47.147 Name: google.com Address: 74.125.47.99 <etc...> 10.254.2.5 is the Win2K3 server. $ ping google.com PING google.com (74.125.47.106) 56(84) bytes of data. It just hangs here indefinitely. $ cat /etc/resolv.conf ; generated by /sbin/dhclient-script search <...snip...>.local nameserver 10.254.2.5 nameserver 10.254.2.124 10.254.2.124 is the backup DC server, which is currently off and tombstoned by this point. The snipped section is our company name. # ifconfig eth0 Link encap:Ethernet HWaddr <snip> inet addr:10.254.2.101 Bcast:10.254.2.255 Mask:255.255.255.0 inet6 addr: <snip>/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:80066 errors:0 dropped:0 overruns:0 frame:0 TX packets:4421 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7810133 (7.4 MiB) TX bytes:590550 (576.7 KiB) Interrupt:225 Base address:0xc000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:32 errors:0 dropped:0 overruns:0 frame:0 TX packets:32 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8104 (7.9 KiB) TX bytes:8104 (7.9 KiB) # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.254.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0 0.0.0.0 10.254.2.5 0.0.0.0 UG 0 0 0 eth0 And, for good measure, a snapshot of the current ethernet config via the system-config-network GUI. Edit: I don't yet have enough rep to post images, so here's a link. Sorry! system-config-network snapshot I'm pretty green when it comes to setting up *nix dev servers and network configuration in general, so please let me know if I've left out critical information, or posted information I shouldn't have posted. Thanks!

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• No external network on ubuntu 9.10, though dns works..

  - by user29368

  Hi, I have a weird problem I cant solve. I have several computers, two with xubuntu 9.10 One of them, acting as a media server, has stopped to work when it comes to external network.. I can do for example: ping google.com Which gives me an ip adress back, like: name@Media:/etc$ ping google.com PING google.com (66.102.9.147) 56(84) bytes of data. That tells me it reaches the dns?, but I get no response at all... If I ping a local computer all works fine. I can also reach the computer via ssh without any problems. I have always used network manager, but now I uninstalled it and made the settings manually like this: /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.1.52 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 192.168.1.1 Still no luck. I have no specific settings for this one in my router, and all the other computers, including my win laptop works fine. This is very annoying since I cant even do an update or anything.. ifconfig looks like this: eth0 Link encap:Ethernet HWaddr 00:24:1d:9f:10:89 inet addr:192.168.1.52 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::224:1dff:fe9f:1089/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:15410 errors:0 dropped:0 overruns:0 frame:0 TX packets:2693 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1167398 (1.1 MB) TX bytes:694973 (694.9 KB) Interrupt:27 Base address:0xe000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:2150 errors:0 dropped:0 overruns:0 frame:0 TX packets:2150 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:143456 (143.4 KB) TX bytes:143456 (143.4 KB) route -n like this Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0 0.0.0.0 192.168.1.1 0.0.0.0 UG 100 0 0 eth0 I do not know where the adress starting with 169.254 comes from.. Could that be a part of the problem? Hoping for some assistance since Im totally stuck here.. /george

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• Parallelism in .NET – Part 13, Introducing the Task class

  - by Reed

  Once we’ve used a task-based decomposition to decompose a problem, we need a clean abstraction usable to implement the resulting decomposition.  Given that task decomposition is founded upon defining discrete tasks, .NET 4 has introduced a new API for dealing with task related issues, the aptly named Task class. The Task class is a wrapper for a delegate representing a single, discrete task within your decomposition.  We will go into various methods of construction for tasks later, but, when reduced to its fundamentals, an instance of a Task is nothing more than a wrapper around a delegate with some utility functionality added.  In order to fully understand the Task class within the new Task Parallel Library, it is important to realize that a task really is just a delegate – nothing more.  In particular, note that I never mentioned threading or parallelism in my description of a Task.  Although the Task class exists in the new System.Threading.Tasks namespace: Tasks are not directly related to threads or multithreading. Of course, Task instances will typically be used in our implementation of concurrency within an application, but the Task class itself does not provide the concurrency used.  The Task API supports using Tasks in an entirely single threaded, synchronous manner. Tasks are very much like standard delegates.  You can execute a task synchronously via Task.RunSynchronously(), or you can use Task.Start() to schedule a task to run, typically asynchronously.  This is very similar to using delegate.Invoke to execute a delegate synchronously, or using delegate.BeginInvoke to execute it asynchronously. The Task class adds some nice functionality on top of a standard delegate which improves usability in both synchronous and multithreaded environments. The first addition provided by Task is a means of handling cancellation via the new unified cancellation mechanism of .NET 4.  If the wrapped delegate within a Task raises an OperationCanceledException during it’s operation, which is typically generated via calling ThrowIfCancellationRequested on a CancellationToken, or if the CancellationToken used to construct a Task instance is flagged as canceled, the Task’s IsCanceled property will be set to true automatically.  This provides a clean way to determine whether a Task has been canceled, often without requiring specific exception handling. Tasks also provide a clean API which can be used for waiting on a task.  Although the Task class explicitly implements IAsyncResult, Tasks provide a nicer usage model than the traditional .NET Asynchronous Programming Model.  Instead of needing to track an IAsyncResult handle, you can just directly call Task.Wait() to block until a Task has completed.  Overloads exist for providing a timeout, a CancellationToken, or both to prevent waiting indefinitely.  In addition, the Task class provides static methods for waiting on multiple tasks – Task.WaitAll and Task.WaitAny, again with overloads providing time out options.  This provides a very simple, clean API for waiting on single or multiple tasks. Finally, Tasks provide a much nicer model for Exception handling.  If the delegate wrapped within a Task raises an exception, the exception will automatically get wrapped into an AggregateException and exposed via the Task.Exception property.  This exception is stored with the Task directly, and does not tear down the application.  Later, when Task.Wait() (or Task.WaitAll or Task.WaitAny) is called on this task, an AggregateException will be raised at that point if any of the tasks raised an exception.  For example, suppose we have the following code: Task taskOne = new Task( () => { throw new ApplicationException("Random Exception!"); }); Task taskTwo = new Task( () => { throw new ArgumentException("Different exception here"); }); // Start the tasks taskOne.Start(); taskTwo.Start(); try { Task.WaitAll(new[] { taskOne, taskTwo }); } catch (AggregateException e) { Console.WriteLine(e.InnerExceptions.Count); foreach (var inner in e.InnerExceptions) Console.WriteLine(inner.Message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, our routine will print: 2 Different exception here Random Exception! Note that we had two separate tasks, each of which raised two distinctly different types of exceptions.  We can handle this cleanly, with very little code, in a much nicer manner than the Asynchronous Programming API.  We no longer need to handle TargetInvocationException or worry about implementing the Event-based Asynchronous Pattern properly by setting the AsyncCompletedEventArgs.Error property.  Instead, we just raise our exception as normal, and handle AggregateException in a single location in our calling code.

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• Bluetooth DUN Tethering fails

  - by tacone

  I have an HTC Desire HD, with Android Froyo (2.2) and PDANet installed. I am using Ubuntu 10.10. I cannot tether it over Bluetooth either with Network Manager or BlueMan. (note, I installed Blueman only after failing with NetWork manager, and I even tried the last version from the PPA). With both my device is discovered, paired, setup. But connecting always fail. Network manager says it cannot get the details of my device Blueman says Connection Refused (111) Here are some relevant entries from syslog. Mar 11 22:13:00 tacone-macbook bluetoothd[2242]: Bluetooth deamon 4.69 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting SDP server Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting experimental netlink support Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to find Bluetooth netlink family Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to init netlink plugin Mar 11 22:13:00 tacone-macbook kernel: [ 158.284357] Bluetooth: L2CAP ver 2.14 Mar 11 22:13:00 tacone-macbook kernel: [ 158.284361] Bluetooth: L2CAP socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.446781] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 Mar 11 22:13:00 tacone-macbook kernel: [ 158.446784] Bluetooth: BNEP filters: protocol multicast Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 registered Mar 11 22:13:00 tacone-macbook kernel: [ 158.569481] Bluetooth: SCO (Voice Link) ver 0.6 Mar 11 22:13:00 tacone-macbook kernel: [ 158.569484] Bluetooth: SCO socket layer initialized Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 up Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting security manager 0 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: ioctl(HCIUNBLOCKADDR): Invalid argument (22) Mar 11 22:13:00 tacone-macbook kernel: [ 158.818600] Bluetooth: RFCOMM TTY layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818607] Bluetooth: RFCOMM socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818610] Bluetooth: RFCOMM ver 1.11 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Adapter /org/bluez/2242/hci0 has been enabled Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from ListDevices reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:13:00 tacone-macbook NetworkManager[1247]: <warn> bluez error getting adapter properties: Rejected send message, 1 matched rules; type="method_call", sender=":1.4" (uid=0 pid=1247 comm="NetworkManager) interface="org.bluez.Adapter" member="GetProperties" error name="(unset)" requested_reply=0 destination="org.bluez" (uid=0 pid=2242 comm="/usr/sbin/bluetoothd)) Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: return_link_keys (sba=00:23:6C:B5:03:6F, dba=00:23:6C:C0:F1:B0) Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:02 tacone-macbook bluetoothd[2243]: Discovery session 0x2262d7c0 with :1.45 activated Mar 11 22:15:15 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:15 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: io_capa_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:17 tacone-macbook bluetoothd[2243]: io_capa_response (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:18 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_notify (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE, type=5) Mar 11 22:15:28 tacone-macbook kernel: [ 306.585725] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.630757] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: Authentication requested Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:28 tacone-macbook kernel: [ 306.784829] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.857861] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: last message repeated 8 times Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:30 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0): probe requested by plugin 'Generic' Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:49 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:16:15 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:16:19 tacone-macbook kernel: [ 357.375108] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.169506] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.215529] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.281559] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.330588] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Any help ? PS: tethering via USB or WiFi is not an option, I need to do it over Bluetooth.

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• Comments on Comments

  - by Joe Mayo

  I almost tweeted a reply to Capar Kleijne's question about comments on Twitter, but realized that my opinion exceeded 140 characters. The following is based upon my experience with extremes and approaches that I find useful in code comments. There are a couple extremes that I've seen and reasons why people go the distance in each approach. The most common extreme is no comments in the code at all.  A few bad reasons why this happens is because a developer is in a hurry, sloppy, or is interested in job preservation. The unfortunate result is that the code is difficult to understand and hard to maintain. The drawbacks to no comments in code are a primary reason why teachers drill the need for commenting code into our heads.  This viewpoint assumes the lack of comments are bad because the code is bad, but there is another reason for not commenting that is gaining more popularity. I've heard/and read that code should be self documenting. Following this thought pattern, if code is well written with meaningful names, there should not be a reason for comments.  An addendum to this argument is that comments are often neglected and get out-of-date, but the code is what is kept up-to-date. Presumably, if code contained very good naming, it would be easy to maintain.  This is a noble perspective and I like the practice of meaningful naming of identifiers. However, I think it's also an extreme approach that doesn't cover important cases.  i.e. If an identifier is named badly (subjective differences in opinion) or not changed appropriately during maintenance, then the badly named identifier is no more useful than a stale comment. These were the two no-comment extremes, so let's look at the too many comments extreme. On a regular basis, I'll see cases where the code is over-commented; not nearly as often as the no-comment scenarios, but still prevalent.  These are examples of where every single line in the code is commented.  These comments make the code harder to read because they get in the way of the algorithm.  In most cases, the comments parrot what each line of code does.  If a developer understands the language, then most statements are immediately intuitive.  i.e. what use is it to say that I'm assigning foo to bar when it's clear what the code is doing. I think that over-commenting code is a waste of time that slows down initial development and maintenance.  Understandably, the developer's intentions are admirable because they've had it beaten into their heads that they must comment. However, I think it's an extreme and prefer a more moderate approach. I don't think the extremes do justice to code because each can make maintenance harder.  No comments on bad code is obviously a problem, but the other two extremes are subtle and require qualification to address properly. The problem I see with the code-as-documentation approach is that it doesn't lift the developer out of the algorithm to identify dependencies, intentions, and hacks. Any developer can read code and follow an algorithm, but they still need to know where it fits into the big picture of the application. Because of indirections with language features like interfaces, delegates, and virtual members, code can become complex.  Occasionally, it's useful to point out a nuance or reason why a piece of code is there. i.e. If you've building an app that communicates via HTTP, you'll have certain headers to include for the endpoint, and it could be useful to point out why the code for setting those header values is there and how they affect the application. An argument against this could be that you should extract that code into a separate method with a meaningful name to describe the scenario.  My problem with such an approach would be that your code base becomes even more difficult to navigate and work with because you have all of this extra code just to make the code more meaningful. My opinion is that a simple and well-stated comment stating the reasons and intention for the code is more natural and convenient to the initial developer and maintainer.  I just don't agree with the approach of going out of the way to avoid making a comment.  I'm also concerned that some developers would take this approach as an excuse to not comment their bad code. Another area where I like comments is on documentation comments.  Java has it and so does C# and VB.  It's convenient because we can build automated tools that extract these comments.  These extracted comments are often much better than no documentation at all.  The "go read the code" answer always doesn't fulfill the need for a quick summary of an API. To summarize, I think that the extremes of no comments and too many comments are less than desirable approaches. I prefer documentation comments to explain each class and member (API level) and code comments as necessary to supplement well-written code. Joe

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• Rob Blackwell on interoperability and Azure

  - by Eric Nelson

  At QCon in March we had a sample Azure application implemented in both Java and Ruby to demonstrate that the Windows Azure Platform is not just about .NET. The following is an interesting interview with Rob Blackwell, the R&D director of the partner who implemented the application. UK Interoperability Team Interviews Rob Blackwell, R&D Director at Active Web Solutions. Is Microsoft taking interoperability seriously? Yes. In the past, I think Microsoft has, quite rightly come in for criticism, but architects and developers should look at this again. The Interoperability Bridges site (http://www.interoperabilitybridges.com/ ) shows a wide range of projects that allow interoperability from Java, Ruby and PHP for example. The Windows Azure platform has been architected with interoperable APIs in mind. It's straightforward to access the various storage facilities from just about any language or platform. Azure compute is capable of running more than just C# applications! Why is interoperability important to you? My company provides consultancy and bespoke development services. We're a Microsoft Gold Partner, but we live in the real world where companies have a mix of technologies provided by a variety of vendors. When developing an enterprise software solution, you rarely have a completely blank canvas. We often see integration scenarios where we need to exchange data with legacy systems. It's not unusual to see modern Silverlight applications being built on top of Java or Mainframe based back ends. Could you give us some examples of where interoperability has been important for your projects? We developed an innovative Sea Safety system for the RNLI Lifeboats here in the UK. Commercial Fishing is one of the most dangerous professions and we helped developed the MOB Guardian System which uses satellite technology and man overboard devices to raise the alarm when a fisherman gets into trouble. The solution is implemented in .NET running on Windows, but without interoperable standards, it would have been impossible to communicate with the satellite gateway technology. For more information, please see the case study: http://www.microsoft.com/casestudies/Case_Study_Detail.aspx?CaseStudyID=4000005892 More recently, we were asked to build a web site to accompany the QCon 2010 conference in London to help demonstrate and promote interoperability. We built the site using Java and Restlet and hosted it in Windows Azure Compute. The site accepts feedback from visitors and all the data is stored in Windows Azure Storage. We also ported the application to Ruby on Rails for demonstration purposes. Visitors to the stand were surprised that this was even possible. Why should Java developers be interested in Windows Azure? Windows Azure Storage consists of Blobs, Queues and Tables. The storage is scalable, durable, secure and cost-effective. Using the WindowsAzure4j library, it's easy to use, and takes just a few lines of code. If you are writing an application with large data storage requirements, or you want an offsite backup, it makes a lot of sense. Running Java applications in Azure Compute is straightforward with tools like the Tomcat Solution Accelerator (http://code.msdn.microsoft.com/winazuretomcat )and AzureRunMe (http://azurerunme.codeplex.com/ ). The Windows Azure AppFabric Service Bus can also be used to connect heterogeneous systems running on different networks and in different data centres. How can The Service Bus be considered an interoperability solution? I think that the Windows Azure AppFabric Service Bus is one of Microsoft’s best kept secrets. Think of it as “a globally scalable application plumbing kit in the sky”. If you have used Enterprise Service Buses before, you’ll be familiar with the concept. Applications can connect to the service bus to securely exchange data – these can be point to point or multicast links. With the AppFabric Service Bus, the applications can exist anywhere that has access to the Internet and the connections can traverse firewalls. This makes it easy to extend or scale your application or reach out to other networks and technologies. For example, let’s say you have a SQL Server database running on premises and you want to expose the data to a Java application running in the cloud. You could set up a point to point Service Bus connection and use JDBC. Traditionally this would have been difficult or impossible without punching holes in firewalls and compromising security. Rob Blackwell is R&D Director at Active Web Solutions, www.aws.net , a Microsoft Gold Partner specialising in leading edge software solutions. He is an occasional writer and conference speaker and blogs at www.robblackwell.org.uk Related Links: UK Azure Online Community – join today. UK Windows Azure Site Start working with Windows Azure

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• Parallelism in .NET – Part 17, Think Continuations, not Callbacks

  - by Reed

  In traditional asynchronous programming, we’d often use a callback to handle notification of a background task’s completion.  The Task class in the Task Parallel Library introduces a cleaner alternative to the traditional callback: continuation tasks. Asynchronous programming methods typically required callback functions.  For example, MSDN’s Asynchronous Delegates Programming Sample shows a class that factorizes a number.  The original method in the example has the following signature: public static bool Factorize(int number, ref int primefactor1, ref int primefactor2) { //... .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, calling this is quite “tricky”, even if we modernize the sample to use lambda expressions via C# 3.0.  Normally, we could call this method like so: int primeFactor1 = 0; int primeFactor2 = 0; bool answer = Factorize(10298312, ref primeFactor1, ref primeFactor2); Console.WriteLine("{0}/{1} [Succeeded {2}]", primeFactor1, primeFactor2, answer); If we want to make this operation run in the background, and report to the console via a callback, things get tricker.  First, we need a delegate definition: public delegate bool AsyncFactorCaller( int number, ref int primefactor1, ref int primefactor2); Then we need to use BeginInvoke to run this method asynchronously: int primeFactor1 = 0; int primeFactor2 = 0; AsyncFactorCaller caller = new AsyncFactorCaller(Factorize); caller.BeginInvoke(10298312, ref primeFactor1, ref primeFactor2, result => { int factor1 = 0; int factor2 = 0; bool answer = caller.EndInvoke(ref factor1, ref factor2, result); Console.WriteLine("{0}/{1} [Succeeded {2}]", factor1, factor2, answer); }, null); This works, but is quite difficult to understand from a conceptual standpoint.  To combat this, the framework added the Event-based Asynchronous Pattern, but it isn’t much easier to understand or author. Using .NET 4’s new Task<T> class and a continuation, we can dramatically simplify the implementation of the above code, as well as make it much more understandable.  We do this via the Task.ContinueWith method.  This method will schedule a new Task upon completion of the original task, and provide the original Task (including its Result if it’s a Task<T>) as an argument.  Using Task, we can eliminate the delegate, and rewrite this code like so: var background = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); background.ContinueWith(task => Console.WriteLine("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result)); This is much simpler to understand, in my opinion.  Here, we’re explicitly asking to start a new task, then continue the task with a resulting task.  In our case, our method used ref parameters (this was from the MSDN Sample), so there is a little bit of extra boiler plate involved, but the code is at least easy to understand. That being said, this isn’t dramatically shorter when compared with our C# 3 port of the MSDN code above.  However, if we were to extend our requirements a bit, we can start to see more advantages to the Task based approach.  For example, supposed we need to report the results in a user interface control instead of reporting it to the Console.  This would be a common operation, but now, we have to think about marshaling our calls back to the user interface.  This is probably going to require calling Control.Invoke or Dispatcher.Invoke within our callback, forcing us to specify a delegate within the delegate.  The maintainability and ease of understanding drops.  However, just as a standard Task can be created with a TaskScheduler that uses the UI synchronization context, so too can we continue a task with a specific context.  There are Task.ContinueWith method overloads which allow you to provide a TaskScheduler.  This means you can schedule the continuation to run on the UI thread, by simply doing: Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }).ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), TaskScheduler.FromCurrentSynchronizationContext()); This is far more understandable than the alternative.  By using Task.ContinueWith in conjunction with TaskScheduler.FromCurrentSynchronizationContext(), we get a simple way to push any work onto a background thread, and update the user interface on the proper UI thread.  This technique works with Windows Presentation Foundation as well as Windows Forms, with no change in methodology.

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• Simple-Talk development: a quick history lesson

  - by Michael Williamson

  Up until a few months ago, Simple-Talk ran on a pure .NET stack, with IIS as the web server and SQL Server as the database. Unfortunately, the platform for the site hadn’t quite gotten the love and attention it deserved. On the one hand, in the words of our esteemed editor Tony “I’d consider the current platform to be a “success”; it cost $10K, has lasted for 6 years, was finished, end to end in 6 months, and although we moan about it has got us quite a long way.” On the other hand, it was becoming increasingly clear that it needed some serious work. Among other issues, we had authors that wouldn’t blog because our current blogging platform, Community Server, was too painful for them to use. Forgetting about Simple-Talk for a moment, if you ask somebody what blogging platform they’d choose, the odds are they’d say WordPress. Regardless of its technical merits, it’s probably the most popular blogging platform, and it certainly seemed easier to use than Community Server. The issue was that WordPress is normally hosted on a Linux stack running PHP, Apache and MySQL — quite a difference from our Microsoft technology stack. We certainly didn’t want to rewrite the entire site — we just wanted a better blogging platform, with the rest of the existing, legacy site left as is. At a very high level, Simple-Talk’s technical design was originally very straightforward: when your browser sends an HTTP request to Simple-Talk, IIS (the web server) takes the request, does some work, and sends back a response. In order to keep the legacy site running, except with WordPress running the blogs, a different design is called for. We now use nginx as a reverse-proxy, which can then delegate requests to the appropriate application: So, when your browser sends a request to Simple-Talk, nginx takes that request and checks which part of the site you’re trying to access. Most of the time, it just passes the request along to IIS, which can then respond in much the same way it always has. However, if your request is for the blogs, then nginx delegates the request to WordPress. Unfortunately, as simple as that diagram looks, it hides an awful lot of complexity. In particular, the legacy site running on IIS was made up of four .NET applications. I’ve already mentioned one of these applications, Community Server, which handled the old blogs as well as managing membership and the forums. We have a couple of other applications to manage both our newsletters and our articles, and our own custom application to do some of the rendering on the site, such as the front page and the articles. When I say that it was made up of four .NET applications, this might conjure up an image in your mind of how they fit together: You might imagine four .NET applications, each with their own database, communicating over well-defined APIs. Sadly, reality was a little disappointing: We had four .NET applications that all ran on the same database. Worse still, there were many queries that happily joined across tables from multiple applications, meaning that each application was heavily dependent on the exact data schema that each other application used. Add to this that many of the queries were at least dozens of lines long, and practically identical to other queries except in a few key spots, and we can see that attempting to replace one component of the system would be more than a little tricky. However, the problems with the old system do give us a good place to start thinking about desirable qualities from any changes to the platform. Specifically: Maintainability — the tight coupling between each .NET application made it difficult to update any one application without also having to make changes elsewhere Replaceability — the tight coupling also meant that replacing one component wouldn’t be straightforward, especially if it wasn’t on a similar Microsoft stack. We’d like to be able to replace different parts without having to modify the existing codebase extensively Reusability — we’d like to be able to combine the different pieces of the system in different ways for different sites Repeatable deployments — rather than having to deploy the site manually with a long list of instructions, we should be able to deploy the entire site with a single command, allowing you to create a new instance of the site easily whether on production, staging servers, test servers or your own local machine Testability — if we can deploy the site with a single command, and each part of the site is no longer dependent on the specifics of how every other part of the site works, we can begin to run automated tests against the site, and against individual parts, both to prevent regressions and to do a little test-driven development In the next part, I’ll describe the high-level architecture we now have that hopefully brings us a little closer to these five traits.

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• A C# implementation of the CallStream pattern

  - by Bertrand Le Roy

  Dusan published this interesting post a couple of weeks ago about a novel JavaScript chaining pattern: http://dbj.org/dbj/?p=514 It’s similar to many existing patterns, but the syntax is extraordinarily terse and it provides a new form of friction-free, plugin-less extensibility mechanism. Here’s a JavaScript example from Dusan’s post: CallStream("#container") (find, "div") (attr, "A", 1) (css, "color", "#fff") (logger); The interesting thing here is that the functions that are being passed as the first argument are arbitrary, they don’t need to be declared as plug-ins. Compare that with a rough jQuery equivalent that could look something like this: $.fn.logger = function () { /* ... */ } $("selector") .find("div") .attr("A", 1) .css("color", "#fff") .logger(); There is also the “each” method in jQuery that achieves something similar, but its syntax is a little more verbose. Of course, that this pattern can be expressed so easily in JavaScript owes everything to the extraordinary way functions are treated in that language, something Douglas Crockford called “the very best part of JavaScript”. One of the first things I thought while reading Dusan’s post was how I could adapt that to C#. After all, with Lambdas and delegates, C# also has its first-class functions. And sure enough, it works really really well. After about ten minutes, I was able to write this: CallStreamFactory.CallStream (p => Console.WriteLine("Yay!")) (Dump, DateTime.Now) (DumpFooAndBar, new { Foo = 42, Bar = "the answer" }) (p => Console.ReadKey()); Where the Dump function is: public static void Dump(object options) { Console.WriteLine(options.ToString()); } And DumpFooAndBar is: public static void DumpFooAndBar(dynamic options) { Console.WriteLine("Foo is {0} and bar is {1}.", options.Foo, options.Bar); } So how does this work? Well, it really is very simple. And not. Let’s say it’s not a lot of code, but if you’re like me you might need an Advil after that. First, I defined the signature of the CallStream method as follows: public delegate CallStream CallStream (Action<object> action, object options = null); The delegate define a call stream as something that takes an action (a function of the options) and an optional options object and that returns a delegate of its own type. Tricky, but that actually works, a delegate can return its own type. Then I wrote an implementation of that delegate that calls the action and returns itself: public static CallStream CallStream (Action<object> action, object options = null) { action(options); return CallStream; } Pretty nice, eh? Well, yes and no. What we are doing here is to execute a sequence of actions using an interesting novel syntax. But for this to be actually useful, you’d need to build a more specialized call stream factory that comes with some sort of context (like Dusan did in JavaScript). For example, you could write the following alternate delegate signature that takes a string and returns itself: public delegate StringCallStream StringCallStream(string message); And then write the following call stream (notice the currying): public static StringCallStream CreateDumpCallStream(string dumpPath) { StringCallStream str = null; var dump = File.AppendText(dumpPath); dump.AutoFlush = true; str = s => { dump.WriteLine(s); return str; }; return str; } (I know, I’m not closing that stream; sure; bad, bad Bertrand) Finally, here’s how you use it: CallStreamFactory.CreateDumpCallStream(@".\dump.txt") ("Wow, this really works.") (DateTime.Now.ToLongTimeString()) ("And that is all."); Next step would be to combine this contextual implementation with the one that takes an action parameter and do some really fun stuff. I’m only scratching the surface here. This pattern could reveal itself to be nothing more than a gratuitous mind-bender or there could be applications that we hardly suspect at this point. In any case, it’s a fun new construct. Or is this nothing new? You tell me… Comments are open :)

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• Slow boot on Ubuntu 12.04

  - by Hailwood

  My Ubuntu is booting really slow (Windows is booting faster...). I am using Ubuntu a Dell Inspiron 1545 Pentium(R) Dual-Core CPU T4300 @ 2.10GHz, 4GB Ram, 500GB HDD running Ubuntu 12.04 with gnome-shell 3.4.1. After running dmesg the culprit seems to be this section, in particular the last three lines: [26.557659] ADDRCONF(NETDEV_UP): eth0: link is not ready [26.565414] ADDRCONF(NETDEV_UP): eth0: link is not ready [27.355355] Console: switching to colour frame buffer device 170x48 [27.362346] fb0: radeondrmfb frame buffer device [27.362347] drm: registered panic notifier [27.362357] [drm] Initialized radeon 2.12.0 20080528 for 0000:01:00.0 on minor 0 [27.617435] init: udev-fallback-graphics main process (1049) terminated with status 1 [30.064481] init: plymouth-stop pre-start process (1500) terminated with status 1 [51.708241] CE: hpet increased min_delta_ns to 20113 nsec [59.448029] eth2: no IPv6 routers present But I have no idea how to start debugging this. sudo lshw -C video $ sudo lshw -C video *-display description: VGA compatible controller product: RV710 [Mobility Radeon HD 4300 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 32 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=fglrx_pci latency=0 resources: irq:48 memory:e0000000-efffffff ioport:de00(size=256) memory:f6df0000-f6dfffff memory:f6d00000-f6d1ffff After loading the propriety driver my new dmesg log is below (starting from the first major time gap): [2.983741] EXT4-fs (sda6): mounted filesystem with ordered data mode. Opts: (null) [25.094327] ADDRCONF(NETDEV_UP): eth0: link is not ready [25.119737] udevd[520]: starting version 175 [25.167086] lp: driver loaded but no devices found [25.215341] fglrx: module license 'Proprietary. (C) 2002 - ATI Technologies, Starnberg, GERMANY' taints kernel. [25.215345] Disabling lock debugging due to kernel taint [25.231924] wmi: Mapper loaded [25.318414] lib80211: common routines for IEEE802.11 drivers [25.318418] lib80211_crypt: registered algorithm 'NULL' [25.331631] [fglrx] Maximum main memory to use for locked dma buffers: 3789 MBytes. [25.332095] [fglrx] vendor: 1002 device: 9552 count: 1 [25.334206] [fglrx] ioport: bar 1, base 0xde00, size: 0x100 [25.334229] pci 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [25.334235] pci 0000:01:00.0: setting latency timer to 64 [25.337109] [fglrx] Kernel PAT support is enabled [25.337140] [fglrx] module loaded - fglrx 8.96.4 [Mar 12 2012] with 1 minors [25.342803] Adding 4189180k swap on /dev/sda7. Priority:-1 extents:1 across:4189180k [25.364031] type=1400 audit(1338241723.027:2): apparmor="STATUS" operation="profile_load" name="/sbin/dhclient" pid=606 comm="apparmor_parser" [25.364491] type=1400 audit(1338241723.031:3): apparmor="STATUS" operation="profile_load" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=606 comm="apparmor_parser" [25.364760] type=1400 audit(1338241723.031:4): apparmor="STATUS" operation="profile_load" name="/usr/lib/connman/scripts/dhclient-script" pid=606 comm="apparmor_parser" [25.394328] wl 0000:0c:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [25.394343] wl 0000:0c:00.0: setting latency timer to 64 [25.415531] acpi device:36: registered as cooling_device2 [25.416688] input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A03:00/device:34/LNXVIDEO:00/input/input6 [25.416795] ACPI: Video Device [VID] (multi-head: yes rom: no post: no) [25.416865] [Firmware Bug]: Duplicate ACPI video bus devices for the same VGA controller, please try module parameter "video.allow_duplicates=1"if the current driver doesn't work. [25.425133] lib80211_crypt: registered algorithm 'TKIP' [25.448058] snd_hda_intel 0000:00:1b.0: PCI INT A -> GSI 21 (level, low) -> IRQ 21 [25.448321] snd_hda_intel 0000:00:1b.0: irq 47 for MSI/MSI-X [25.448353] snd_hda_intel 0000:00:1b.0: setting latency timer to 64 [25.738867] eth1: Broadcom BCM4315 802.11 Hybrid Wireless Controller 5.100.82.38 [25.761213] input: HDA Intel Mic as /devices/pci0000:00/0000:00:1b.0/sound/card0/input7 [25.761406] input: HDA Intel Headphone as /devices/pci0000:00/0000:00:1b.0/sound/card0/input8 [25.783432] dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2) [25.908318] EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro [25.928155] input: Dell WMI hotkeys as /devices/virtual/input/input9 [25.960561] udevd[543]: renamed network interface eth1 to eth2 [26.285688] init: failsafe main process (835) killed by TERM signal [26.396426] input: PS/2 Mouse as /devices/platform/i8042/serio2/input/input10 [26.423108] input: AlpsPS/2 ALPS GlidePoint as /devices/platform/i8042/serio2/input/input11 [26.511297] Bluetooth: Core ver 2.16 [26.511383] NET: Registered protocol family 31 [26.511385] Bluetooth: HCI device and connection manager initialized [26.511388] Bluetooth: HCI socket layer initialized [26.511391] Bluetooth: L2CAP socket layer initialized [26.512079] Bluetooth: SCO socket layer initialized [26.530164] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 [26.530168] Bluetooth: BNEP filters: protocol multicast [26.553893] type=1400 audit(1338241724.219:5): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=928 comm="apparmor_parser" [26.554860] Bluetooth: RFCOMM TTY layer initialized [26.554866] Bluetooth: RFCOMM socket layer initialized [26.554868] Bluetooth: RFCOMM ver 1.11 [26.557910] type=1400 audit(1338241724.223:6): apparmor="STATUS" operation="profile_load" name="/usr/lib/lightdm/lightdm/lightdm-guest-session-wrapper" pid=927 comm="apparmor_parser" [26.559166] type=1400 audit(1338241724.223:7): apparmor="STATUS" operation="profile_replace" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=928 comm="apparmor_parser" [26.559574] type=1400 audit(1338241724.223:8): apparmor="STATUS" operation="profile_replace" name="/usr/lib/connman/scripts/dhclient-script" pid=928 comm="apparmor_parser" [26.575519] type=1400 audit(1338241724.239:9): apparmor="STATUS" operation="profile_load" name="/usr/lib/telepathy/mission-control-5" pid=931 comm="apparmor_parser" [26.581100] type=1400 audit(1338241724.247:10): apparmor="STATUS" operation="profile_load" name="/usr/lib/telepathy/telepathy-*" pid=931 comm="apparmor_parser" [26.582794] type=1400 audit(1338241724.247:11): apparmor="STATUS" operation="profile_load" name="/usr/bin/evince" pid=929 comm="apparmor_parser" [26.605672] ppdev: user-space parallel port driver [27.592475] sky2 0000:09:00.0: eth0: enabling interface [27.604329] ADDRCONF(NETDEV_UP): eth0: link is not ready [27.606962] ADDRCONF(NETDEV_UP): eth0: link is not ready [27.852509] vesafb: mode is 1024x768x32, linelength=4096, pages=0 [27.852513] vesafb: scrolling: redraw [27.852515] vesafb: Truecolor: size=0:8:8:8, shift=0:16:8:0 [27.852523] mtrr: type mismatch for e0000000,400000 old: write-back new: write-combining [27.852527] mtrr: type mismatch for e0000000,200000 old: write-back new: write-combining [27.852531] mtrr: type mismatch for e0000000,100000 old: write-back new: write-combining [27.852534] mtrr: type mismatch for e0000000,80000 old: write-back new: write-combining [27.852538] mtrr: type mismatch for e0000000,40000 old: write-back new: write-combining [27.852541] mtrr: type mismatch for e0000000,20000 old: write-back new: write-combining [27.852544] mtrr: type mismatch for e0000000,10000 old: write-back new: write-combining [27.852548] mtrr: type mismatch for e0000000,8000 old: write-back new: write-combining [27.852551] mtrr: type mismatch for e0000000,4000 old: write-back new: write-combining [27.852554] mtrr: type mismatch for e0000000,2000 old: write-back new: write-combining [27.852558] mtrr: type mismatch for e0000000,1000 old: write-back new: write-combining [27.853154] vesafb: framebuffer at 0xe0000000, mapped to 0xffffc90005580000, using 3072k, total 3072k [27.853405] Console: switching to colour frame buffer device 128x48 [27.853426] fb0: VESA VGA frame buffer device [28.539800] fglrx_pci 0000:01:00.0: irq 48 for MSI/MSI-X [28.540552] [fglrx] Firegl kernel thread PID: 1168 [28.540679] [fglrx] Firegl kernel thread PID: 1169 [28.540789] [fglrx] Firegl kernel thread PID: 1170 [28.540932] [fglrx] IRQ 48 Enabled [29.845620] [fglrx] Gart USWC size:1236 M. [29.845624] [fglrx] Gart cacheable size:489 M. [29.845629] [fglrx] Reserved FB block: Shared offset:0, size:1000000 [29.845632] [fglrx] Reserved FB block: Unshared offset:fc21000, size:3df000 [29.845635] [fglrx] Reserved FB block: Unshared offset:1fffb000, size:5000 [59.700023] eth2: no IPv6 routers present

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• College Courses through distance learning

  - by Matt

  I realize this isn't really a programming question, but didn't really know where to post this in the stackexchange and because I am a computer science major i thought id ask here. This is pretty unique to the programmer community since my degree is about 95% programming. I have 1 semester left, but i work full time. I would like to finish up in December, but to make things easier i like to take online classes whenever I can. So, my question is does anyone know of any colleges that offer distance learning courses for computer science? I have been searching around and found a few potential classes, but not sure yet. I would like to gather some classes and see what i can get approval for. Class I need: Only need one C SC 437 Geometric Algorithms C SC 445 Algorithms C SC 473 Automata Only need one C SC 452 Operating Systems C SC 453 Compilers/Systems Software While i only need of each of the above courses i still need to take two more electives. These also have to be upper 400 level classes. So i can take multiple in each category. Some other classes I can take are: CSC 447 - Green Computing CSC 425 - Computer Networking CSC 460 - Database Design CSC 466 - Computer Security I hoping to take one or two of these courses over the summer. If not, then online over the regular semester would be ok too. Any help in helping find these classes would be awesome. Maybe you went to a college that offered distance learning. Some of these classes may be considered to be graduate courses too. Descriptions are listed below if you need. Thanks! Descriptions Computer Security This is an introductory course covering the fundamentals of computer security. In particular, the course will cover basic concepts of computer security such as threat models and security policies, and will show how these concepts apply to specific areas such as communication security, software security, operating systems security, network security, web security, and hardware-based security. Computer Networking Theory and practice of computer networks, emphasizing the principles underlying the design of network software and the role of the communications system in distributed computing. Topics include routing, flow and congestion control, end-to-end protocols, and multicast. Database Design Functions of a database system. Data modeling and logical database design. Query languages and query optimization. Efficient data storage and access. Database access through standalone and web applications. Green Computing This course covers fundamental principles of energy management faced by designers of hardware, operating systems, and data centers. We will explore basic energy management option in individual components such as CPUs, network interfaces, hard drives, memory. We will further present the energy management policies at the operating system level that consider performance vs. energy saving tradeoffs. Finally we will consider large scale data centers where energy management is done at multiple layers from individual components in the system to shutting down entries subset of machines. We will also discuss energy generation and delivery and well as cooling issues in large data centers. Compilers/Systems Software Basic concepts of compilation and related systems software. Topics include lexical analysis, parsing, semantic analysis, code generation; assemblers, loaders, linkers; debuggers. Operating Systems Concepts of modern operating systems; concurrent processes; process synchronization and communication; resource allocation; kernels; deadlock; memory management; file systems. Algorithms Introduction to the design and analysis of algorithms: basic analysis techniques (asymptotics, sums, recurrences); basic design techniques (divide and conquer, dynamic programming, greedy, amortization); acquiring an algorithm repertoire (sorting, median finding, strong components, spanning trees, shortest paths, maximum flow, string matching); and handling intractability (approximation algorithms, branch and bound). Automata Introduction to models of computation (finite automata, pushdown automata, Turing machines), representations of languages (regular expressions, context-free grammars), and the basic hierarchy of languages (regular, context-free, decidable, and undecidable languages). Geometric Algorithms The study of algorithms for geometric objects, using a computational geometry approach, with an emphasis on applications for graphics, VLSI, GIS, robotics, and sensor networks. Topics may include the representation and overlaying of maps, finding nearest neighbors, solving linear programming problems, and searching geometric databases.

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