Expat-IT Tech Bits

Home

Contact

Links

Search this site:

Categories:

/ (287)
  Admin/ (122)
    Apache/ (10)
      HTTPS-SSL/ (4)
      PHP/ (3)
      performance/ (2)
    Cherokee/ (1)
    LAN/ (4)
    LVM/ (6)
    Monitoring/ (2)
      munin/ (2)
    SSH/ (6)
    SSL/ (1)
    Samba/ (1)
    VPN-options/ (6)
      OpenVPN/ (1)
      SSH-Proxy/ (3)
      Tinc/ (1)
      sshuttle/ (1)
    backups/ (17)
      SpiderOak/ (1)
      backuppc/ (5)
      dirvish/ (1)
      misc/ (6)
      rdiff-backup/ (1)
      rsync/ (1)
      unison/ (2)
    commandLine/ (24)
      files/ (8)
      misc/ (10)
      network/ (6)
    crontab/ (1)
    databases/ (15)
      MSSQL/ (2)
      MySQL/ (8)
      Oracle/ (3)
      PostgreSQL/ (1)
    dynamicDNS/ (2)
    email/ (11)
      Dovecot/ (1)
      deliverability/ (1)
      misc/ (1)
      postfix/ (7)
      puppet/ (1)
    iptables/ (3)
    tripwire/ (1)
    virtualization/ (9)
      VMware/ (1)
      virtualBox/ (8)
  Coding/ (14)
    bash/ (1)
    gdb/ (1)
    git/ (3)
    php/ (5)
    python/ (4)
      Django/ (2)
  Education/ (1)
  Hosting/ (27)
    Amazon/ (18)
      EBS/ (3)
      EC2/ (10)
      S3/ (1)
      commandline/ (4)
    Godaddy/ (2)
    NearlyFreeSpeech/ (3)
    Rackspace/ (1)
    vpslink/ (3)
  Linux/ (30)
    Android/ (1)
    Awesome/ (3)
    CPUfreq/ (1)
    China/ (2)
    Debian/ (8)
      APT/ (3)
      WPA/ (1)
    audio/ (1)
    encryption/ (3)
    fonts/ (1)
    misc/ (6)
    remoteDesktop/ (1)
    router-bridge/ (3)
  SW/ (45)
    Micro$soft/ (1)
    browser/ (2)
      Chrome/ (1)
      Firefox/ (1)
    business/ (28)
      Drupal/ (9)
      KnowledgeTree/ (6)
      Redmine/ (2)
      SugarCRM/ (7)
      WebERP/ (2)
      WordPress/ (1)
      eGroupware/ (1)
    chat/ (1)
    email/ (1)
    fileSharing/ (2)
      btsync/ (1)
      mldonkey/ (1)
    graphics/ (2)
    research/ (2)
    website/ (6)
      blog/ (6)
        blosxom/ (3)
        rss2email/ (1)
        webgen/ (1)
  Security/ (15)
    IMchat/ (2)
    circumvention/ (2)
    cryptoCurrency/ (1)
    e-mail/ (4)
    greatFirewall/ (1)
    hacking/ (1)
    password/ (1)
    privacy/ (2)
    skype/ (1)
  Services/ (1)
    fileSharing/ (1)
  TechWriting/ (1)
  xHW/ (14)
    Lenovo/ (1)
    Motorola_A1200/ (2)
    Thinkpad_600e/ (1)
    Thinkpad_a21m/ (3)
    Thinkpad_i1300/ (1)
    Thinkpad_x24/ (1)
    USB_audio/ (1)
    scanner/ (1)
    wirelessCards/ (2)
  xLife/ (17)
    China/ (9)
      Beijing/ (5)
        OpenSource/ (3)
    Expatriation/ (1)
    Vietnam/ (7)

Archives:

  • 2016/07
  • 2016/05
  • 2016/02
  • 2016/01
  • 2015/12
  • 2015/11
  • 2015/06
  • 2015/01
  • 2014/12
  • 2014/11
  • 2014/10
  • 2014/09
  • 2014/07
  • 2014/04
  • 2014/02
  • 2014/01
  • 2013/12
  • 2013/10
  • 2013/08
  • 2013/07
  • 2013/06
  • 2013/05
  • 2013/04
  • 2013/02
  • 2013/01
  • 2012/12
  • 2012/10
  • 2012/09
  • 2012/08
  • 2012/07
  • 2012/06
  • 2012/05
  • 2012/04
  • 2012/03
  • 2012/01
  • 2011/12
  • 2011/11
  • 2011/10
  • 2011/09
  • 2011/08
  • 2011/07
  • 2011/06
  • 2011/05
  • 2011/04
  • 2011/02
  • 2010/12
  • 2010/11
  • 2010/10
  • 2010/09
  • 2010/08
  • 2010/07
  • 2010/06
  • 2010/05
  • 2010/04
  • 2010/03
  • 2010/02
  • 2010/01
  • 2009/12
  • 2009/11
  • 2009/10
  • 2009/09
  • 2009/08
  • 2009/07
  • 2009/06
  • 2009/05
  • 2009/04
  • 2009/03
  • 2009/02
  • 2009/01
  • 2008/12
  • 2008/11
  • 2008/10
  • 2008/09
  • Subscribe XML RSS Feed

    Creative Commons License
    This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
    PyBlosxom

    This site has no ads. To help with hosting, crypto donations are accepted:
    Bitcoin: 1JErV8ga9UY7wE8Bbf1KYsA5bkdh8n1Bxc
    Zcash: zcLYqtXYFEWHFtEfM6wg5eCV8frxWtZYkT8WyxvevzNC6SBgmqPS3tkg6nBarmzRzWYAurgs4ThkpkD5QgiSwxqoB7xrCxs

    Sun, 27 Dec 2015


    /Admin/commandLine/network: Port/Firewall Testing with Netcat and Socat

    To avoid application-related issues and just do a bare-bones test of whether or not a port is open, use netcat or socat. On the server end, turn off the application that should be listening on port 9092, then:

    FOR NETCAT:

    Start listening on the server side:

    netcat -l -p 9092 (newer versions of netcat)
    netcat -l 9092 (older versions)

    Attempt to connect to the port from the client on the other side of the firewall:

    nc IPADDRESS 9092

    If everything is working, anything you type on either end should be mirrored on the other end.

    FOR SOCAT:

    Start listening on the server side:

    socat TCP4-LISTEN:9092,reuseaddr,fork gopen:/tmp/capture,seek-end=0,append

    Now send some text from the client end to the listener:

    date | socat STDIO tcp:localhost:9092

    In this example, the client is on the same machine, replace "localhost" with an IP or DNS if not. All text sent from the client side will be appended to the file /tmp/capture.

    posted at: 02:44 | path: /Admin/commandLine/network | permanent link to this entry

    Thu, 24 Dec 2015


    /Admin/Apache/PHP: Best Practices for Custom PHP Parameters

    First, do not edit php.ini, instead add a file to

    /etc/php5/conf.d/

    called something like php_ini_local.ini, for instance. Place parameters you would like to customize like upload_max_filesize in there, and they will take precedence over those in the php.ini file(s). And this way php.ini will in future also upgrade gracefully to newer versions without manual intervention.

    To test parameter changes (before and after) the simple way, use PHP CLI in a terminal:

    # php -a <?php echo ini_get('upload_max_filesize'); ?> Ctrl-d

    posted at: 03:47 | path: /Admin/Apache/PHP | permanent link to this entry

    Tue, 15 Dec 2015


    /Admin/virtualization/virtualBox: Increase or Decrease Storage Space for a VirtualBox VM

    Increasing is nearly trivial:

    VBoxManage modifyhd virtualBoxUbuntu.vdi --resize 15000

    for a 15G drive. Then inside the running VM use gparted to increast the main partition size to use all the newly added space.

    To decrease, one can only reduce the amount of variable space used by the image by freeing up all unused space, apparently one cannot reduce the upper limit.

    To free up space, delete unwanted files on the VM, install the zerofree package, then reboot into recovery mode and mount the root (main) partition ro:

    mount -n -o remount,ro -t ext3 /dev/sda1 /

    Then zero out the unused space in the partition:

    zerofree -v /dev/sda1

    And compact the image:

    VBoxManage modifyhd virtualBoxUbuntu.vdi --compact

    You should find the file system that the vdi is located in now has a lot more free space.

    [1] http://dantwining.co.uk/2011/07/18/how-to-shrink-a-dynamically-expanding-guest-virtualbox-image/

    posted at: 02:38 | path: /Admin/virtualization/virtualBox | permanent link to this entry

    Tue, 01 Dec 2015


    /Admin/databases/Oracle: Resetting Administrative Passwords in Oracle

    Login to the server as the "oracle" user (typically).

    Find the sqlplus binary, and login as SYS, for instance:

    /home/oracle/app/oracle/product/12.1.0/dbhome_1/bin/sqlplus "/ as sysdba"

    Then change the SYSTEM password:

    SQL> show user
    SQL> passw system
    SQL> quit
    Then login as SYSTEM:
    /home/oracle/app/oracle/product/12.1.0/dbhome_1/bin/sqlplus "system/password"

    and change the SYS password:

    SQL> show user
    SQL> passw sys
    SQL> quit

    References:
    [1] https://rolfje.wordpress.com/2007/01/16/lost-oracle-sys-and-system-password/

    posted at: 02:11 | path: /Admin/databases/Oracle | permanent link to this entry