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  • Failure connecting to Dell MD3200i from XenServer 6.2 pool

    - by Tom Sparrow
    This question also asked at Citrix Forums http://forums.citrix.com/thread.jspa?threadID=332289 I have a MD3200i that is currently working fine with my Xen5.6 pool, but I cannot get a connection to the new 6.2 pool to work. I previously had a problem with a 6.0 upgrade (which is why the old pool is still on 5.6), but rolled back rather than fix it as it wasn't urgent at the time. This install is on new machines - I tried 6.1 first (which had the same problems) then 6.2 was released the second day after installation so I switched to that. I've not installed anything from the Dell resource DVD at this point - I can't find anything saying I should, and everything I have read suggests it shouldn't be necessary. I can ping all 8 ip addresses from both servers in the pool, iscsiadm -m discovery works fine, I can login to the nodes and iscsiadm reports the sessions active correctly. I've added the required sections to multipath.conf, but multipath -ll reports DM multipath kernel driver not loaded immediately after boot. The following is a log of a test session immediately after boot. root@xen3 ~]# iscsiadm -m node --loginall=all Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.101,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.101,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.104,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.102,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.103,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.104,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.102,3260] Logging in to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.103,3260] Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.101,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.101,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.104,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.102,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.103,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.104,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.130.102,3260]: successful Login to [iface: default, target: iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91, portal: 192.168.131.103,3260]: successful [root@xen3 ~]# iscsiadm -m session tcp: [1] 192.168.130.101:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [2] 192.168.131.101:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [3] 192.168.131.104:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [4] 192.168.131.102:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [5] 192.168.130.103:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [6] 192.168.130.104:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [7] 192.168.130.102:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [8] 192.168.131.103:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 [root@xen3 ~]# service multipathd restart ok Stopping multipathd daemon: [ OK ] Starting multipathd daemon: [ OK ] [root@xen3 ~]# multipath Jul 04 09:58:47 | DM multipath kernel driver not loaded Jul 04 09:58:47 | DM multipath kernel driver not loaded [root@xen3 ~]# multipath -ll Jul 04 09:59:03 | DM multipath kernel driver not loaded Jul 04 09:59:03 | DM multipath kernel driver not loaded [ root@xen3 ~]# modprobe dm_multipath [root@xen3 ~]# multipath Jul 04 10:19:50 | 36b8ca3a0e7024800194a0bd11891cd14: ignoring map create: 1Dell_Internal_Dual_SD_0123456789AB undef Dell,Internal Dual SD size=1.9G features='0' hwhandler='0' wp=undef `-+- policy='round-robin 0' prio=1 status=undef `- 7:0:0:0 sdb 8:16 undef ready running [root@xen3 ~]# multipath -ll 1Dell_Internal_Dual_SD_0123456789AB dm-1 Dell,Internal Dual SD size=1.9G features='0' hwhandler='0' wp=rw `-+- policy='round-robin 0' prio=1 status=enabled `- 7:0:0:0 sdb 8:16 active ready running [root@xen3 ~]# iscsiadm -m session tcp: [1] 192.168.130.101:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [2] 192.168.131.101:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [3] 192.168.131.104:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [4] 192.168.131.102:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [5] 192.168.130.103:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [6] 192.168.130.104:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [7] 192.168.130.102:3260,2 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 tcp: [8] 192.168.131.103:3260,1 iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 [root@xen3 ~]# dmesg | tail -n 50 [ 1161.881010] sd 8:0:0:0: [sdf] Unhandled error code [ 1161.881013] sd 8:0:0:0: [sdf] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1161.881017] sd 8:0:0:0: [sdf] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1161.881024] end_request: I/O error, dev sdf, sector 0 [ 1161.881031] Buffer I/O error on device sdf, logical block 0 [ 1161.881045] sd 15:0:0:0: [sdi] Unhandled error code [ 1161.881048] sd 15:0:0:0: [sdi] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1161.881052] sd 15:0:0:0: [sdi] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1161.881058] end_request: I/O error, dev sdi, sector 0 [ 1161.881065] Buffer I/O error on device sdi, logical block 0 [ 1161.881122] sd 9:0:0:0: [sdg] Unhandled error code [ 1161.881124] sd 9:0:0:0: [sdg] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1161.881126] sd 9:0:0:0: [sdg] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1161.881132] end_request: I/O error, dev sdg, sector 0 [ 1161.881140] Buffer I/O error on device sdg, logical block 0 [ 1168.220951] connection6:0: ping timeout of 15 secs expired, recv timeout 10, last rx 84060, last ping 85060, now 86560 [ 1168.220957] connection7:0: ping timeout of 15 secs expired, recv timeout 10, last rx 84060, last ping 85060, now 86560 [ 1168.220967] connection7:0: detected conn error (1011) [ 1168.220969] connection4:0: ping timeout of 15 secs expired, recv timeout 10, last rx 84060, last ping 85060, now 86560 [ 1168.220973] connection4:0: detected conn error (1011) [ 1168.220975] connection3:0: ping timeout of 15 secs expired, recv timeout 10, last rx 84060, last ping 85060, now 86560 [ 1168.220978] connection3:0: detected conn error (1011) [ 1168.220985] connection6:0: detected conn error (1011) [ 1168.480994] sd 14:0:0:0: [sde] Unhandled error code [ 1168.480998] sd 14:0:0:0: [sde] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1168.481001] sd 14:0:0:0: [sde] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1168.481009] end_request: I/O error, dev sde, sector 0 [ 1168.481015] Buffer I/O error on device sde, logical block 0 [ 1168.481076] sd 11:0:0:0: [sdc] Unhandled error code [ 1168.481078] sd 11:0:0:0: [sdc] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1168.481080] sd 11:0:0:0: [sdc] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1168.481087] end_request: I/O error, dev sdc, sector 0 [ 1168.481092] Buffer I/O error on device sdc, logical block 0 [ 1168.481144] sd 10:0:0:0: [sdd] Unhandled error code [ 1168.481147] sd 10:0:0:0: [sdd] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1168.481150] sd 10:0:0:0: [sdd] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1168.481156] end_request: I/O error, dev sdd, sector 0 [ 1168.481163] Buffer I/O error on device sdd, logical block 0 [ 1168.481168] sd 13:0:0:0: [sdj] Unhandled error code [ 1168.481170] sd 13:0:0:0: [sdj] Result: hostbyte=DID_TRANSPORT_DISRUPTED driverbyte=DRIVER_OK [ 1168.481172] sd 13:0:0:0: [sdj] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 1168.481178] end_request: I/O error, dev sdj, sector 0 [ 1168.481184] Buffer I/O error on device sdj, logical block 0 [ 1457.105996] device-mapper: multipath round-robin: version 1.0.0 loaded [ 1457.106155] device-mapper: multipath: Cannot access device path 8:0: -16 [ 1457.106164] device-mapper: table: 252:1: multipath: error getting device [ 1457.106172] device-mapper: ioctl: error adding target to table [ 1457.171292] device-mapper: multipath: Cannot access device path 8:0: -16 [ 1457.171299] device-mapper: table: 252:1: multipath: error getting device [ 1457.171304] device-mapper: ioctl: error adding target to table [root@xen3 ~]# fdisk -l Disk /dev/sda: 299.4 GB, 299439751168 bytes 255 heads, 63 sectors/track, 36404 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 1 5 40131 de Dell Utility /dev/sda2 * 6 528 4194304 83 Linux Partition 2 does not end on cylinder boundary. /dev/sda3 528 1050 4194304 83 Linux /dev/sda4 1050 36404 283986359+ 8e Linux LVM Disk /dev/sdb: 2040 MB, 2040528896 bytes 255 heads, 63 sectors/track, 248 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 248 1992028+ 83 Linux Disk /dev/dm-1: 2040 MB, 2040528896 bytes 255 heads, 63 sectors/track, 248 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/dm-1p1 1 248 1992028+ 83 Linux [root@xen3 ~]# xe sr-probe type=lvmoiscsi device-config:target=192.168.130.101 device-config:targetIQN=iqn.1984-05.com.dell:powervault.md3200i.6782bcb0006bd850000000004ed88b91 Error code: SR_BACKEND_FAILURE_107 Error parameters: , The SCSIid parameter is missing or incorrect, <?xml version="1.0" ?> <iscsi-target/> Note: the xml ends there correctly on the last line - it doesn't ever return a list of LUNs (and there is one in the group on the SAN for those servers.

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  • Hard drive mounted at / , duplicate mounted hard drive after using MountManager

    - by HellHarvest
    possible duplicate post I'm running 12.04 64bit. My system is a dual boot for both Ubuntu and Windows7. Both operating systems are sharing the drive named "Elements". My volume named "Elements" is a 1TB SATA NTFS hard drive that shows up twice in the side bar in nautilus. One of the icons is functional and even has the convenient "eject" icon next to it. Below is a picture of the left menu in Nautilus, with System Monitor-File Systems tab open on top of it. Can someone advise me about how to get rid of this extra icon? I think the problem is much more deep-rooted than just a GUI glitch on Nautilus' part. The other icon does nothing but spit out the following error when I click on it (image below). This only happened AFTER I tried using Mount Manager to automate mounting the drive at start up. I've already uninstalled Mount Manager, and restarted, but the problem didn't go away. The hard drive does mount automatically now, so I guess that's cool. But now, every time I boot up now and open Nautilus, BOTH of these icons appear, one of which is fictitious and useless. According to the image above and the outputs of several other commands, it appears to be mounted at / In which case, no matter where I am in Nautilus when I try to click on that icon, of course it will tell me that that drive is in use by another program... Nautilus. I'm afraid of trying to unmount this hard drive (sdb6) because of where it appears to be mounted. I'm kind of a noob, and I have this gut feeling that tells me trying to unmount a drive at / will destroy my entire file system. This fear was further strengthened by the output of "$ fsck" at the very bottom of this post. Error immediately below when that 2nd "Elements" hard drive is clicked in Nautilus: Unable to mount Elements Mount is denied because the NTFS volume is already exclusively opened. The volume may be already mounted, or another software may use it which could be identified for example by the help of the 'fuser' command. It's odd to me that that error message above claims that it's an NTFS volume when everything else tell me that it's an ext4 volume. The actual hard drive "Elements" is in fact an NTFS volume. Here's the output of a few commands and configuration files that may be of interest: $ fuser -a / /: 2120r 2159rc 2160rc 2172r 2178rc 2180rc 2188r 2191rc 2200rc 2203rc 2205rc 2206r 2211r 2212r 2214r 2220r 2228r 2234rc 2246rc 2249rc 2254rc 2260rc 2261r 2262r 2277rc 2287rc 2291rc 2311rc 2313rc 2332rc 2334rc 2339rc 2343rc 2344rc 2352rc 2372rc 2389rc 2422r 2490r 2496rc 2501rc 2566r 2573rc 2581rc 2589rc 2592r 2603r 2611rc 2613rc 2615rc 2678rc 2927r 2981r 3104rc 4156rc 4196rc 4206rc 4213rc 4240rc 4297rc 5032rc 7609r 7613r 7648r 9593rc 18829r 18833r 19776r $ sudo df -h Filesystem Size Used Avail Use% Mounted on /dev/sdb6 496G 366G 106G 78% / udev 2.0G 4.0K 2.0G 1% /dev tmpfs 791M 1.5M 790M 1% /run none 5.0M 0 5.0M 0% /run/lock none 2.0G 672K 2.0G 1% /run/shm /dev/sda1 932G 312G 620G 34% /media/Elements /home/solderblob/.Private 496G 366G 106G 78% /home/solderblob /dev/sdb2 188G 100G 88G 54% /media/A2B24EACB24E852F /dev/sdb1 100M 25M 76M 25% /media/System Reserved $ sudo fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00093cab Device Boot Start End Blocks Id System /dev/sda1 2048 1953519615 976758784 7 HPFS/NTFS/exFAT Disk /dev/sdb: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000e8d9b Device Boot Start End Blocks Id System /dev/sdb1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sdb2 206848 392378768 196085960+ 7 HPFS/NTFS/exFAT /dev/sdb3 392380414 1465147391 536383489 5 Extended /dev/sdb5 1456762880 1465147391 4192256 82 Linux swap / Solaris /dev/sdb6 392380416 1448374271 527996928 83 Linux /dev/sdb7 1448376320 1456758783 4191232 82 Linux swap / Solaris Partition table entries are not in disk order $ cat /etc/fstab # <file system> <mount point> <type> <options> <dump> <pass> UUID=77039a2a-83d4-47a1-8a8c-a2ec4e4dfd0e / ext4 defaults 0 1 UUID=F6549CC4549C88CF /media/Elements ntfs-3g users 0 0 $ sudo blkid /dev/sda1: LABEL="Elements" UUID="F6549CC4549C88CF" TYPE="ntfs" /dev/sdb1: LABEL="System Reserved" UUID="5CDE130FDE12E156" TYPE="ntfs" /dev/sdb2: UUID="A2B24EACB24E852F" TYPE="ntfs" /dev/sdb6: UUID="77039a2a-83d4-47a1-8a8c-a2ec4e4dfd0e" TYPE="ext4" $ sudo blkid -c /dev/null (appears to be exactly the same as above) /dev/sda1: LABEL="Elements" UUID="F6549CC4549C88CF" TYPE="ntfs" /dev/sdb1: LABEL="System Reserved" UUID="5CDE130FDE12E156" TYPE="ntfs" /dev/sdb2: UUID="A2B24EACB24E852F" TYPE="ntfs" /dev/sdb6: UUID="77039a2a-83d4-47a1-8a8c-a2ec4e4dfd0e" TYPE="ext4" $ mount /dev/sdb6 on / type ext4 (rw) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) /dev/sda1 on /media/Elements type fuseblk (rw,noexec,nosuid,nodev,allow_other,blksize=4096) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) /home/solderblob/.Private on /home/solderblob type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=76a47b0175afa48d,ecryptfs_fnek_sig=391b2d8b155215f7) gvfs-fuse-daemon on /home/solderblob/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=solderblob) /dev/sdb2 on /media/A2B24EACB24E852F type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096) /dev/sdb1 on /media/System Reserved type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096) $ ls -a . A2B24EACB24E852F Ubuntu 12.04.1 LTS amd64 .. Elements System Reserved $ cat /proc/mounts rootfs / rootfs rw 0 0 sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0 proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0 udev /dev devtmpfs rw,relatime,size=2013000k,nr_inodes=503250,mode=755 0 0 devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 tmpfs /run tmpfs rw,nosuid,relatime,size=809872k,mode=755 0 0 /dev/disk/by-uuid/77039a2a-83d4-47a1-8a8c-a2ec4e4dfd0e / ext4 rw,relatime,user_xattr,acl,barrier=1,data=ordered 0 0 none /sys/fs/fuse/connections fusectl rw,relatime 0 0 none /sys/kernel/debug debugfs rw,relatime 0 0 none /sys/kernel/security securityfs rw,relatime 0 0 none /run/lock tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k 0 0 none /run/shm tmpfs rw,nosuid,nodev,relatime 0 0 /dev/sda1 /media/Elements fuseblk rw,nosuid,nodev,noexec,relatime,user_id=0,group_id=0,allow_other,blksize=4096 0 0 binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0 /home/solderblob/.Private /home/solderblob ecryptfs rw,relatime,ecryptfs_fnek_sig=391b2d8b155215f7,ecryptfs_sig=76a47b0175afa48d,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs 0 0 gvfs-fuse-daemon /home/solderblob/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0 /dev/sdb2 /media/A2B24EACB24E852F fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096 0 0 /dev/sdb1 /media/System\040Reserved fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096 0 0 gvfs-fuse-daemon /root/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=0,group_id=0 0 0 $ fsck fsck from util-linux 2.20.1 e2fsck 1.42 (29-Nov-2011) /dev/sdb6 is mounted. WARNING!!! The filesystem is mounted. If you continue you ***WILL*** cause ***SEVERE*** filesystem damage. Do you really want to continue<n>? no check aborted.

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  • Ubuntu 12.04 + Wifi not working

    - by user171154
    i'm having problems connecting over wireless. At the moment, I'm using wicd. It seems to get stuck on "Verifying AP association...". Without wicd I can get the connection up and ping the Net - but if I take eth0 down (ifconfig eth0 down), my wireless goes away too (same result if I unplug the wire instead). wicd is the only way I can bring eth0 back (which is the main reason I'm using it) - ifconfig eth0 and/or ifup eth0 do not re-enable the connection (I just discovered it leaves out the gateway. Adding the gateway back in re-enables the connection including wifi; I didn't want to delete the info about wicd above in case it gives someone an idea.) Doing it manually, despite the errors (which it would be nice to also resolve) - allows me to ping the outside world: ifup wlan0 ioctl[SIOCSIWENCODEEXT]: Invalid argument ioctl[SIOCSIWENCODEEXT]: Invalid argument ssh stop/waiting ssh start/running, process 17336 ping -I wlan0 -c 4 8.8.8.8 PING 8.8.8.8 (8.8.8.8) from 192.168.0.12 wlan0: 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_req=1 ttl=43 time=48.8 ms 64 bytes from 8.8.8.8: icmp_req=2 ttl=43 time=47.9 ms 64 bytes from 8.8.8.8: icmp_req=3 ttl=43 time=48.7 ms 64 bytes from 8.8.8.8: icmp_req=4 ttl=43 time=53.2 ms --- 8.8.8.8 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3003ms rtt min/avg/max/mdev = 47.975/49.711/53.235/2.063 ms # iwconfig lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:"TPLINK" Mode:Managed Frequency:2.427 GHz Access Point: 64:66:xx:xx:xx:22 Bit Rate=108 Mb/s Tx-Power=27 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=70/70 Signal level=-39 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:3 Missed beacon:0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 01 serial: f0:7d:68:c1:b4:13 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.2.0-67-generic-pae firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:17 memory:dfbf0000-dfbfffff ip route default via 192.168.0.1 dev eth0 default via 192.168.0.1 dev wlan0 metric 100 169.254.0.0/16 dev wlan0 scope link metric 1000 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.102 192.168.0.0/24 dev wlan0 proto kernel scope link src 192.168.0.12 (For the record, I have no idea what the 169.254.0.0 address is doing there.) uname -a 3.2.0-67-generic-pae #101-Ubuntu SMP Tue Jul 15 18:04:54 UTC 2014 i686 i686 i386 GNU/Linux lshw -C network *-network description: Ethernet interface product: NetXtreme BCM5751 Gigabit Ethernet PCI Express vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: 01 serial: 00:11:11:59:fc:09 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm vpd msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.121 duplex=full firmware=5751-v3.23a ip=192.168.0.102 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:16 memory:dfcf0000-dfcfffff *-network description: Wireless interface product: AR5418 Wireless Network Adapter [AR5008E 802.11(a)bgn] (PCI-Express) vendor: Qualcomm Atheros physical id: 0 /etc/network/interfaces # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback source /etc/network/interfaces.eth0 source /etc/network/interfaces.wlan0 /etc/network/interfaces.eth0 #Main Interface auto eth0 iface eth0 inet static address 192.168.0.102 netmask 255.255.255.0 gateway 192.168.0.1 /etc/network/interfaces.wlan0 auto wlan0 iface wlan0 inet static address 192.168.0.12 gateway 192.168.0.1 dns-nameservers 192.168.0.1 8.8.8.8 netmask 255.255.255.0 wpa-driver wext wpa-ssid TPLINK wpa-ap-scan 1 wpa-proto RSN wpa-pairwise CCMP wpa-group CCMP wpa-key-mgmt WPA-PSK wpa-psk dca1badb5fd4e9axxx4xxdaaxxfa91xx610bxx6a7d57ef67af9809dxx6af42e39 /etc/wpa_supplicant.conf ctrl_interface=/var/run/wpa_supplicant network={ ssid="TPLINK" psk="my password" key_mgmt=WPA-PSK proto=RSN pairwise=CCMP group=CCMP } ifdown eth0 ifdown: interface eth0 not configured ifconfig eth0 Link encap:Ethernet HWaddr 00:11:xx:xx:xx:09 inet addr:192.168.0.102 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::211:11ff:fe59:fc09/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:213690 errors:0 dropped:0 overruns:0 frame:0 TX packets:155266 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:220057808 (220.0 MB) TX bytes:21137696 (21.1 MB) Interrupt:16 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:196412 errors:0 dropped:0 overruns:0 frame:0 TX packets:196412 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:153270697 (153.2 MB) TX bytes:153270697 (153.2 MB) wlan0 Link encap:Ethernet HWaddr f0:7d:xx:xx:xx:13 inet addr:192.168.0.12 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::f27d:68ff:fec1:b413/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:11335 errors:0 dropped:0 overruns:0 frame:0 TX packets:7287 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2563290 (2.5 MB) TX bytes:855746 (855.7 KB) ifconfig eth0 down ifconfig eth0 Link encap:Ethernet HWaddr 00:xx:xx:xx:xx:09 inet addr:192.168.0.102 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::211:11ff:fe59:fc09/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2 errors:0 dropped:0 overruns:0 frame:0 TX packets:1 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:192 (192.0 B) TX bytes:94 (94.0 B) Interrupt:16 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:196418 errors:0 dropped:0 overruns:0 frame:0 TX packets:196418 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:153270871 (153.2 MB) TX bytes:153270871 (153.2 MB) wlan0 Link encap:Ethernet HWaddr f0:7d:xx:xx:xx:13 inet addr:192.168.0.12 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::f27d:68ff:fec1:b413/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:11359 errors:0 dropped:0 overruns:0 frame:0 TX packets:7293 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2565482 (2.5 MB) TX bytes:856363 (856.3 KB) ip route default via 192.168.0.1 dev wlan0 metric 100 169.254.0.0/16 dev wlan0 scope link metric 1000 192.168.0.0/24 dev wlan0 proto kernel scope link src 192.168.0.12 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.102 ping -I wlan0 -c 4 8.8.8.8 PING 8.8.8.8 (8.8.8.8) from 192.168.0.12 wlan0: 56(84) bytes of data. --- 8.8.8.8 ping statistics --- 4 packets transmitted, 0 received, 100% packet loss, time 3024ms ping -I eth0 -c 3 router PING router (192.168.0.1) from 192.168.0.102 eth0: 56(84) bytes of data. --- router ping statistics --- 3 packets transmitted, 0 received, 100% packet loss, time 2015ms ping -I wlan0 -c 3 router PING router (192.168.0.1) from 192.168.0.12 wlan0: 56(84) bytes of data. --- router ping statistics --- 3 packets transmitted, 0 received, 100% packet loss, time 2014ms Let me know if you need more info. Thank you in advance.

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  • Linux router: ping doesn't route back

    - by El Barto
    I have a Debian box which I'm trying to set up as a router and an Ubuntu box which I'm using as a client. My problem is that when the Ubuntu client tries to ping a server on the Internet, all the packets are lost (though, as you can see below, they seem to go to the server and back without problem). I'm doing this in the Ubuntu Box: # ping -I eth1 my.remote-server.com PING my.remote-server.com (X.X.X.X) from 10.1.1.12 eth1: 56(84) bytes of data. ^C --- my.remote-server.com ping statistics --- 13 packets transmitted, 0 received, 100% packet loss, time 12094ms (I changed the name and IP of the remote server for privacy). From the Debian Router I see this: # tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 7, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 8, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 8, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 9, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 9, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 10, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 10, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 11, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 11, length 64 ^C 9 packets captured 9 packets received by filter 0 packets dropped by kernel # tcpdump -i eth2 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth2, link-type EN10MB (Ethernet), capture size 65535 bytes IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 213, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 213, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 214, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 214, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 215, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 215, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 216, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 216, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 217, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 217, length 64 ^C 10 packets captured 10 packets received by filter 0 packets dropped by kernel And at the remote server I see this: # tcpdump -i eth0 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 1, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 1, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 2, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 2, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 3, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 3, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 4, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 4, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 5, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 5, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 6, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 6, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 7, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 7, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 8, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 8, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 9, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 9, length 64 18 packets captured 228 packets received by filter 92 packets dropped by kernel Here "X.X.X.X" is my remote server's IP and "Y.Y.Y.Y" is my local network's public IP. So, what I understand is that the ping packets are coming out of the Ubuntu box (10.1.1.12), to the router (10.1.1.1), from there to the next router (192.168.1.1) and reaching the remote server (X.X.X.X). Then they come back all the way to the Debian router, but they never reach the Ubuntu box back. What am I missing? Here's the Debian router setup: # ifconfig eth1 Link encap:Ethernet HWaddr 94:0c:6d:82:0d:98 inet addr:10.1.1.1 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::960c:6dff:fe82:d98/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:105761 errors:0 dropped:0 overruns:0 frame:0 TX packets:48944 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:40298768 (38.4 MiB) TX bytes:44831595 (42.7 MiB) Interrupt:19 Base address:0x6000 eth2 Link encap:Ethernet HWaddr 6c:f0:49:a4:47:38 inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::6ef0:49ff:fea4:4738/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:38335992 errors:0 dropped:0 overruns:0 frame:0 TX packets:37097705 errors:0 dropped:0 overruns:0 carrier:1 collisions:0 txqueuelen:1000 RX bytes:4260680226 (3.9 GiB) TX bytes:3759806551 (3.5 GiB) Interrupt:27 eth3 Link encap:Ethernet HWaddr 94:0c:6d:82:c8:72 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:20 Base address:0x2000 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:3408 errors:0 dropped:0 overruns:0 frame:0 TX packets:3408 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:358445 (350.0 KiB) TX bytes:358445 (350.0 KiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:2767779 errors:0 dropped:0 overruns:0 frame:0 TX packets:1569477 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:3609469393 (3.3 GiB) TX bytes:96113978 (91.6 MiB) # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.8.0.2 0.0.0.0 255.255.255.255 UH 0 0 0 tun0 127.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 lo 10.8.0.0 10.8.0.2 255.255.255.0 UG 0 0 0 tun0 192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth2 10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth2 # arp -n # Note: Here I have changed all the different MACs except the ones corresponding to the Ubuntu box (on 10.1.1.12 and 192.168.1.12) Address HWtype HWaddress Flags Mask Iface 192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.102 ether NN:NN:NN:NN:NN:NN C eth2 10.1.1.12 ether 00:1e:67:15:2b:f0 C eth1 192.168.1.86 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.2 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.40 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.12 ether 00:1e:67:15:2b:f1 C eth2 192.168.1.77 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.41 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.123 ether NN:NN:NN:NN:NN:NN C eth2 # iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination # iptables -L -n -t nat Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- 10.1.1.0/24 !10.1.1.0/24 MASQUERADE all -- !10.1.1.0/24 10.1.1.0/24 Chain OUTPUT (policy ACCEPT) target prot opt source destination And here's the Ubuntu box: # ifconfig eth0 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f1 inet addr:192.168.1.12 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::21e:67ff:fe15:2bf1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:28785139 errors:0 dropped:0 overruns:0 frame:0 TX packets:19050735 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:32068182803 (32.0 GB) TX bytes:6061333280 (6.0 GB) Interrupt:16 Memory:b1a00000-b1a20000 eth1 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f0 inet addr:10.1.1.12 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::21e:67ff:fe15:2bf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:285086 errors:0 dropped:0 overruns:0 frame:0 TX packets:12719 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:30817249 (30.8 MB) TX bytes:2153228 (2.1 MB) Interrupt:16 Memory:b1900000-b1920000 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:86048 errors:0 dropped:0 overruns:0 frame:0 TX packets:86048 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:11426538 (11.4 MB) TX bytes:11426538 (11.4 MB) # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 0.0.0.0 10.1.1.1 0.0.0.0 UG 100 0 0 eth1 10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 10.8.0.0 192.168.1.10 255.255.255.0 UG 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0 192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0 # arp -n # Note: Here I have changed all the different MACs except the ones corresponding to the Debian box (on 10.1.1.1 and 192.168.1.10) Address HWtype HWaddress Flags Mask Iface 192.168.1.70 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.97 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.103 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.13 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.120 (incomplete) eth0 192.168.1.111 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.51 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.102 (incomplete) eth0 192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.74 (incomplete) eth0 192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.121 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.71 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.88 (incomplete) eth0 192.168.1.82 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.98 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.73 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.11 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.85 (incomplete) eth0 192.168.1.112 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.81 ether NN:NN:NN:NN:NN:NN C eth0 10.1.1.1 ether 94:0c:6d:82:0d:98 C eth1 192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.10 ether 6c:f0:49:a4:47:38 C eth0 192.168.1.86 (incomplete) eth0 192.168.1.119 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth1 192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth0 # iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination # iptables -L -n -t nat Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain INPUT (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination Edit: Following Patrick's suggestion, I did a tcpdump con the Ubuntu box and I see this: # tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 1, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 1, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 2, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 2, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 3, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 3, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 4, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 4, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 5, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 5, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 6, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 6, length 64 ^C 12 packets captured 12 packets received by filter 0 packets dropped by kernel So the question is: if all packets seem to be coming and going, why does ping report 100% packet loss?

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  • A VS2010 Project Made From Post: How to: Host a WCF Service in a Managed Windows Service

    MSDN has a very nice article on how to create a windows service that hosts a Windows Communication Foundation (WCF) service.  It explains all the details of doing this in a step by step... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Visual Basic 2010 Language Enhancements

    Earlier this month Microsoft released Visual Studio 2010, the .NET Framework 4.0 (which includes ASP.NET 4.0), and new versions of their core programming languages: C# 4.0 and Visual Basic 10 (also referred to as Visual Basic 2010). Previously, the C# and Visual Basic programming languages were managed by two separate teams within Microsoft, which helps explain why features found in one language was not necessarily found in the other. For example, C# 3.0 introduced <a href="http://weblogs.asp.net/scottgu/archive/2007/03/08/new-c-orcas-language-features-automatic-properties-object-initializers-and-collection-initializers.aspx"><i>collection initializers</i></a>, which enable developers to define the contents of a collection when declaring it; however,

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  • Are there any famous one-man-army programmers?

    - by DFectuoso
    Lately I have been learning of more and more programmers who think that if they were working alone, they would be faster and would deliver more quality. Usually that feeling is attached to a feeling that they do the best programming in their team and at the end of the day the idea is quite plausible. If they ARE doing the best programming, and worked alone (and more maybe) the final result would be a better piece of software. I know this idea would only work if you were passionate enough to work 24/7, on a deadline, with great discipline. So after considering the idea and trying to learn a little more, I wonder if there are famous one-man-army programmers that have delivered any (useful) software in the past?

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  • Silverlight Cream for March 08, 2010 -- #809

    - by Dave Campbell
    In this Issue: Michael Washington, Tim Greenfield, Bobby Diaz(-2-), Glenn Block(-2-), Nikhil Kothari, Jianqiang Bao(-2-), and Christopher Bennage. Shoutouts: Adam Kinney announced a Big update for the Project Rosetta site today Arpit Gupta has opened a new blog with a great logo: I think therefore I am dangerous :) From SilverlightCream.com: DotNetNuke Silverlight Traffic Module If it's DNN and Silverlight, it has to be my buddy Michael Washington :) ... Michael has combined those stunning gauges you've seen with website traffic... just too cool!... grab the code and display yours too! Cool demonstration of Silverlight VideoBrush This is a no-code post by Tim Greenfield, but I like the UX on this Jigsaw Puzzle page... and you can make your own. Introducing the Earthquake Locator – A Bing Maps Silverlight Application, part 1 Bobby Diaz has an informative post up on combining earthquake data with BingMaps in Silverlight 3... check it out, the grab the recently posted Live Demo and Source Code Adding Volcanos and Options - Earthquake Locator, part 2 Bobby Diaz also added volcanic activity to his earthquake BinMaps app, and updated the downloadable code and live demo. Building Hello MEF – Part IV – DeploymentCatalog Glenn Block posted a pair of MEF posts yesterday... made me think I missed one :) .. the first one is about the DeploymentCatalog. Note he is going to be using the CodePlex bits in his posts. Building HelloMEF – Part V – Refactoring to ViewModel Glenn Block's part V is about MEF and MVVM -- no, really! ... he is refactoring MVVM into the app with a nod to Josh Smith and Laurent Bugnion... get your head around this... The Case for ViewModel Nikhil Kothari has a post up about the ViewModel, and how it facilitates designer/developer workflow, jumpstarts development, improves scaling, and makes asynch programming development simpler MMORPG programming in Silverlight Tutorial (12)Map Instance (Part I) Jianqiang Bao has part 12 of his MMORPG game up... this one is showing how to deal with obstuctions on maps. MMORPG programming in Silverlight Tutorial (13)Perfect moving mechanism Jianqiang Bao also has part 13 up, and this second one is about sprite movement around the obstructions. 1 Simple Step for Commanding in Silverlight Christopher Bennage blogged about Commanding in Silverlight, he begins with a blog post about commands in Silverlight 4 then goes on to demonstrate the Caliburn way of doing commanding. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    MIX10

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  • Red Gate Coder interviews: Robin Hellen

    - by Michael Williamson
    Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

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  • How can Swift be so much faster than Objective-C in these comparisons?

    - by Yellow
    Apple launched its new programming language Swift at WWDC14. In the presentation, they made some performance comparisons between Objective-C and Python. The following is a picture of one of their slides, of a comparison of those three languages performing some complex object sort: There was an even more incredible graph about a performance comparison using the RC4 encryption algorithm. Obviously this is a marketing talk, and they didn't go into detail on how this was implemented in each. I leaves me wondering though: How can a new programming language be so much faster? Are the Objective-C results caused by a bad compiler or is there something less efficient in Objective-C than Swift? How would you explain a 40% performance increase? I understand that garbage collection/automated reference control might produce some additional overhead, but this much?

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  • what, why, when, should I learn computer science?

    - by dramasea
    I'm 16 years old and really an enthusiast on web programming. I know (X)HTML, css, javascript and php. And i heard about computer science. Below are my question: What is computer science? Should a web programmer learn computer science? If the answer of question 2 is yes, then what programming language(s) should I learn before I get into computer science (I saw the video of 'Introduction to computer science' which is one of the MIT opencourse and it started to use python without teaching you from scratch.) Can I learn computer science now? (Without a university degree, I can watch open courseware.)

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  • c++ write own xml parser vs using tinyxml

    - by AdityaGameProgrammer
    Hi , I am currently in a task to generate an XML file for an srt text file containing timestamps and corresponding text. To generate an exe file which accepts file name input and outputs the relevant XML file to be used as part of an automated script. Is it Advisable to use Tinyxml for this? Is this a very simple task that can be done with minimal programming? Is this one of those things which are very basic to c++ programmers? reason i am asking this is I have recently made a shift into c++ programming after over 3 years of action script development. Edit: your comments regarding this are very much appreciated what's the easiest way to generate xml in c++?

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  • Sitting At MIX10 In Michael Scherotters Presentation of the Silverlight 4 Search Analytics Framework

      As usual, Michaels doing a great job of presenting enthusiastically the new Silverlight Analytics Frameworks.  Im hugely impressed with how easy it is going to be to add analytics to a... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Can my ikmnet test results say something about career choice I should take?

    - by Nicke
    I took 2 tests via ikmnet and scored 70 % on SQL and 65 % on Java. While not bad, it can be improved. The subskills I need to improve according to the test are interfaces and inheritance, compilation and deployment, flow control, The java.lang package and "Java Program Construction" and these topics seems rather broad to me. Rather than just learning by programming, could you advice me to take a certification, follow a course or otherwise improve my skills? By the way, I enjoy python more than Java so should I market myself more of a python programmer or even a role that some companies search for which seems like a system developer with more technical writing where the title is system analysts (evaluating systems in cooperation with management rather than programming.) Thank you for any comment and/or answer.

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  • Rain effect using DirectX 9 capabilities

    - by teodron
    Is it possible to achieve something similar to nVidia's rain demo using only shader model 3.0 capabilities? If yes, could you point out a few documents/web resources that are suitable candidates and do not require a heavy programming load (e.g. not more than two hard weeks of programming for one single person)? It would be nice if the answer could also contain a pro/con phrase for the proposed idea (e.g. postprocessing rain shader vs. a particle based effect).

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  • My History with Agile

    - by Robert May
    I’m going to write my history with Agile here.  That way, in future posts, I can refer back to it, instead of typing it out in the post that contains information you may actually want to read.  Note that I’m actually a pretty senior developer, and do lots of technical interviews.  I’m an Agile fan because of the difference it makes in peoples lives and the improvement in quality it brings, and I’ll sacrifice my technological advance to help teams. Management History I started management pretty early in my career, starting with the first job that I ever had.  I actually do NOT have a CS or similar degree.  I have a Bachelor’s of Business Administration with an emphasis in Computer Information Systems. My first management gigs were around call center work and were very schedule oriented.  I didn’t understand the true value of teams, and I’m ashamed to admit, I actually installed a fingerprint scanner as a time clock in this job.  I shudder to think of the impact that I had on the team spirit.  I didn’t even trust them enough to fill out their time cards correctly.  How sad. I was managing nearly 100 people in this position, with the help of a great set of subordinates. I did try to come up with reward programs for the team, but again, didn’t understand the concept of team, so instead of letting the team determine how the rewards should work, I mandated from on high, which isn’t a good thing. I was told that I wasn’t the type that would be a good manager by people whom I respected a lot.  They said it because I was a computer geek, since they don’t understand good management either, but in retrospect, they were right about me then.  I was too green. After my first job, I went on to other jobs and with the exception of one job, I’ve managed people at them all.  The rest of the management story is important for understanding agile, so I’ll save it for my next post. Technical History I’ve been in software development for many, many years.  I technically started programming on a commodore 64 in basic.  I didn’t know that I was programming, but I was sure having fun.  That was followed by batch files, Gorilla hacking (I always had to win), WordPerfect Macro programming and other things that taught me the basics. My first “real” job was with a telephone company, and that’s where I made my first database application in DataEase, wrote my first VBA app and started using real programming tools, like turbo pascal, vb3-vb5, and semi-real tools like RPG and VisualRPG.  I wrote my first web page in 1994, and built my first data driven web page in 1995 using perlDB.  You really can do anything with Perl.  At this time, I also started a Linux based internet service provider that is still in operation today.  One of the people I worked with is now a Microsoft employee building and designing frameworks you probably know well.  Smart guy.  I also built my first ASP applications connecting to Sql Server 6.5, setup Exchange 5.5 for the company, and many other system administration stuff.  I’m a programmer by choice, mostly because I don’t really like PC support. From there, I went on to a large state agency.  I got to see and maintain true waterfall projects.  5 years of maintaining the 200 VB COM+ (MTS, actually) dlls that were used to calculate a single number is a long time.  That was all Microsoft DNS technologies.  SQL Server and VB6 were the tools of choice, although .net started to be a factor near the end of employment.  I did some heavy XML work at this job and even wrote an XSD parser and validator in VB6 that was a shim until MSXML 3.0 came out.  Prior to 3.0, XSD’s weren’t supported, and I didn’t want to write DTDs. Ironically, jobs after this were more generic.  I pretty much settled in on the .net framework and revisions of it.  Lots of WPF, some silverlight, lots of ASP.NET, some SQL Azure, lots of SQL Server, some Oracle, but I don’t think that I was as passionate about development and technologies.  I was more into the management of development.  I like people. Technorati Tags: Agile,history

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  • NET Math Libraries

    - by JoshReuben
    NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

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  • what, why, when, should I learn computer science?

    - by dramasea
    I'm 16 years old and really an enthusiast on web programming. I know (X)HTML, css, javascript and php. And i heard about computer science. Below are my question: What is computer science is? Should a web programmer learn computer science? If the answer of question 2 is yes, then what programming language should i learn before i get into computer science(I saw the video of 'Introduction to computer science' which is one of the MIT opencourse and it started to use python without teaching u from scratch) Can I learn computer science now?(Without a university degree, i can watch opencourseware)

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  • A toolset for self improvement and learning [closed]

    - by Sebastian
    Possible Duplicate: I’m having trouble learning I've been working as an IT consultant for 1½ years and I am very passionate about programming. Before that I studied MSc Software Engineering and had both a part time job as a developer for a big telecom company. During that time I also took extra courses and earned a SCJP certificate. I have been continuously reading a lot of books during the last 3½ years. Now to my problem. I want to continue learning and become a really, really good developer. Apart from my daytime job as a full time java developer I have taken university courses in, for me, new languages and paradigms. Most recently, android game development and then functional programming with Scala. I've read books, went to conferences and had a couple of presentations for internal training purposes in our local office. I want to have some advice from other people who have previously been in my situation or currently are. What are you guys doing to keep improving yourselves? Here is some things that I have found are working for me: Reading books I've mostly read books about best practices for programming, OO-design, refactoring, design patterns, tdd. Software craftmanship if you like. I keep a reading list and my current book is Apprenticeship patterns. Taking courses In my country we have a really good system for taking online distance courses. I have also taken one course at coursera.org and a highly recommend that platform. Ive looked at courses at oreilly.com, industriallogic, javaspecialists.eu and they seem to be okay. If someone gives these type of courses a really good review, I can probably convince my boss. Workshops that span over a couple of days would probably be harder, but Ive seen that uncle Bob will have one about refactoring and tdd in 6months not far from here.. :) Are their possibly some online learning platforms that I dont know about? Educational videos I've bought uncle bobs videos from cleancoders.com and I highly recommend them. The only thing I dont like is that they are quite expensive and that he talks about astronomy for ~10 minutes in every episode. Getting certified I had a lot of fun and learned a lot when I studied for the SCJP. I have also done some preparation for the microsoft equivalent but never went for it. I think it is a good when selling yourself as a newly graduated student and also will boost your knowledge if your are interested in it. Now I would like others to start sharing their experiences and possibly give me some advice! BR Sebastian

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  • Writing C# Code Using SOLID Principles

    - by bipinjoshi
    Most of the modern programming languages including C# support objected oriented programming. Features such as encapsulation, inheritance, overloading and polymorphism are code level features. Using these features is just one part of the story. Equally important is to apply some object oriented design principles while writing your C# code. SOLID principles is a set of five such principles--namely Single Responsibility Principle, Open/Closed Principle, Liskov Substitution Principle, Interface Segregation Principle and Dependency Inversion Principle. Applying these time proven principles make your code structured, neat and easy to maintain. This article discusses SOLID principles and also illustrates how they can be applied to your C# code.http://www.binaryintellect.net/articles/7f857089-68f5-4d76-a3b7-57b898b6f4a8.aspx 

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  • Writing A Transact SQL (TSQL) Procedure For SQL Server 2008 To Delete Rows From Table Safely

    In this post, we will show and explain a small TSQL Sql Server 2008 procedure that deletes all rows in a table that are older than some specified date.  That is, say the table has 10,000,000... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Using SqlServer 2008 and TSQL Subtract 1 Hour From All Values In a DateTime Column

    In this post, well go briefly the process of how you would update all rows in a SQL Server 2008 table such that a particular date column will be moved back 1 hour in time.  This is actually... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • who are software design engineers?

    - by Sepala
    My question is, who are software design engineers? And, what is the meaning of the following statement (from a software design engineer job ad)? "Application domain knowledge is essential and....." What is application domain? SDLC? My hope is to become a software engineer one day (OK, to be honest, more than that. I need to be a legend), that who do programming (They say this job has no programming). I am following final year of my Bsc(Hons) in computing and I have completed a foreign diploma, majoring software engineering - Java technologies. Will this job experience help me out to get a job in my desired position, which is mentioned above, after the degree? Wikipedia and google never gave a clear straight forward answer!! Please help!

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  • O&rsquo;Reilly offer to 05:00 PT 12/Aug/2014 - Ivor Horton's Beginning Visual C++ 2013

    - by TATWORTH
    Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/08/05/orsquoreilly-offer-to-0500-pt-12aug2014---ivor-hortons-beginning.aspxUntil 05:00 PT 12/Aug/2014, O’Reilly at http://shop.oreilly.com/product/9781118845714.do?code=WKCPPS are offering 50% off Ivor Horton's Beginning Visual C++ 2013. “This latest edition of the bestselling book on the C++ language follows the proven approach that has made all of Ivor Horton’s C++ books so popular. Horton provides a comprehensive introduction to both the Standard C++ language, and to Visual C++. The book—thoroughly updated for the 2013 release—shows readers how to build real-world applications using Visual C++. No previous programming experience is required. The author uses numerous step-by-step programming examples to guide readers through the ins and outs of C++ development.”

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