Windows update error 8024402C

When windows update gives error 8024402C, and the machine is not managed by WSUS and has internet connection, the problem could be solved by executing following command line:

netsh winhttp reset proxy

Updating to Windows 10 when having GRUB 2 bootloader installed in MBR.

Usually when having dualboot of Windows and Linux the GRUB 2 bootloader is installed in MBR. When trying to update to Windows 10 it fails with the following error "We Can't Tell if your PC has enough space to continue".
Well the solution for updating to Windows 10 is simple - restore the hardisk Master Boot Record (MBR) using Windows installation disc (it can be also created via Microsoft's MediaCreationTool - the same tool used for updating to Windows 10. Just on the first screen choose not to update, but "Create installation media for another PC" and write it to DVD/USB).
Boot from the Windows installation DVD/USB and follow instruction until screen that allows you to install windows or "Repair your computer". Choose to "Repair your computer" / "Troubleshoot" / "Advanced options" / "Command prompt"
Execute following command:

bootrec.exe /fixmbr

Reboot and start the update process again. Now the update should be successful.
Now Windows boots successfully but Linux is no longer accessible. One way to make Linux bootable again is to use Windows bootloader to load Linux. I prefer this method because I don't want to face any future problems with windows updates.
We need a copy of the GRUB2 exported as file. For that reason we will install GRUB on Partition Boot Record (PBR) and copy the boot sector to file. First we must access the installed Linux partitions. Create a "Live CD" on DVD/USB and boot from it. The from the shell mount your existing linux installation. Let's assume that /dev/sda3 is the linux boot partition, /dev/sda4 is the root partition. Now mount the volumes:

mount /dev/sda4 /mnt
mount /dev/sda3 /mnt/boot
mount --bind /dev /mnt/dev
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys

Optionally you may mount home directory

mount /dev/sdaX /mnt/home

Now do chroot:

chroot /mnt

Reinstall grup 2 on boot partition

grub2-install /dev/sda3

You may receive following error:
"warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged.
error: will not proceed with blocklists"
Then just use --force

grub2-install --force /dev/sda3

Once the installation complets create a dump of the bootsector:

dd if=/dev/sda3 of=/tmp/linux.bootsector.bin bs=512 count=1

copy the /tmp/linux.bootsector.bin  to some partition accessible by Windows.

mkdir /mnt/c

mount /dev/sda2 /mnt/c

cp /tmp/linux.bootsector.bin /mnt/c

umount /mnt/c

Now reboot and start Windows and we need to create a new BCD entry for Linux
Open administrative command prompt (right click on "command prompt" and choose run as administrator)

bcdedit /create /d “Linux” /application BOOTSECTOR

The command will return GUID e.g. {5474794d-1fe8-4008-a0ae-d10210214f2a}
That GUID will be use in next commands.
Configure new BCD entry's partition and path to the location where linux.bootsector.bin is copied

bcdedit /set {5474794d-1fe8-4008-a0ae-d10210214f2a} device partition=C: 

bcdedit /set {5474794d-1fe8-4008-a0ae-d10210214f2a}  PATH \linux.bootsector.bin

Then configure the new entry to be shown last, and the OS selection menu timeout to be 5 seconds.

bcdedit /displayorder {5474794d-1fe8-4008-a0ae-d10210214f2a}  /addlast

bcdedit /timeout 5

Reboot and now you will be able to boot either Windows or Linux.

Windows 10/8/7/Vista administrative shares are not accessible (from linux / windows)

The information is based on Access Denied Trying to Connect to Administrative Shares C$, D$ etc.

Typical error is :

mount -t cifs -o username=superman,password=secret //192.168.22.14/c$ /mnt/c
mount error(13): Permission denied
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

The reason is that described in KB951916 Microsoft introduced as part of UAC a little known feature called “UAC remote restrictions”. It filters the access token for connections made with local user accounts or Microsoft accounts (the latter typically have the format MicrosoftAccount\EMailAddress). In other words it removes the SID for “Administrators”. Connections made with domain accounts remain unchanged. From KB951016:

If the user wants to administer the workstation with a Security Account Manager (SAM) account, the user must interactively log on to the computer that is to be administered with Remote Assistance or Remote Desktop, if these services are available.

UAC remote restrictions can be disabled by setting the DWORD registry value LocalAccountTokenFilterPolicy to 1:

Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
Value: LocalAccountTokenFilterPolicy
Data: 1 (to disable, 0 enables filtering)
Type: REG_DWORD (32-bit)

Reboot is not required on Windows 8/10

OpeneElec Kodi hacking - creating music catalog

Systemd CIFS mount

/storage/.config/system.d/storage-music-rock.mount

[Unit]
 Description=cifs mount script
 Requires=network-online.service
 After=network-online.service
 Before=kodi.service

 [Mount]
 What=//192.168.0.31/MusicRock
 Where=/storage/music/rock
 Options=username=myusername,password=mypassword,rw
 Type=cifs

 [Install]
 WantedBy=multi-user.target

Important: this file must be renamed to mountpoint.mount where mountpoint, is the FULL path where the share will be mounted. Slashes "/" MUST BE REPLACED with dashes "-" with .mount as extension. This means, if we want mount to "/storage/music/rock" (see above "Where=/storage/music/rock") then this file must be renamed to 'storage-music-rock.mount'. This is only for the filename! not for the What= and Where= sections!

Script that maps file by the first two letters

/storage/.config/create_symb_links.sh chmod +s /storage/.config/create_symb_links.sh

#!/bin/bash
displayUsage() { 
  echo "Scans source directory and create symbolic links based on the file first two letters" 
  echo -e "\nUsage:\n$0 [src-dir] [links-dir]\n  src-dir\tsource directory to be scanned\n  links-dir\tfull path to target directory where symbolic links will be created\n\n" 
  echo -e "e.g.:\n $0 /storage/music/rock /storage/music/rock_links/\n\n"
  echo -e "Let's have 3 files:\n    /storage/music/rock/rock1\n    /storage/music/rock/rock2\n    /storage/music/rock/metal\n"
  echo -e "then inside /storage/music/rock_links/ you will have following files:\n"
  echo -e "    /storage/music/rock_links/RO/rock1\n    /storage/music/rock_links/RO/rock2\n    /storage/music/rock_links/ME/metal\n"
} 


if [[ -z $1 ]]; then
  displayUsage
  exit 1 
fi

if [[ -z $2 ]]; then
  displayUsage
  exit 1 
fi

dir=$1
links=$2
currdir=`pwd`

rm -Rf $links

cd $dir

mkdir -p $links
for f in *
do 
  prefix=`echo $f | cut -c 1,2 | tr [:lower:] [:upper:]`
  mkdir -p $links/$prefix
  ln -s "$dir/$f" "$links/$prefix/$f"
done

cd $currdir

Service for creating music catalog

/storage/.config/system.d/catalog-music-rock.service

[Unit]
Description=Create musics catalog
Requires=storage-music-rock.mount
After=storage-music-rock.mount
Before=kodi.service

[Service]
Type=oneshot
ExecStartPre=/bin/bash -c 'echo "Creating music catalog ..."'
ExecStart=/bin/bash -c '/storage/.config/create_symb_links.sh  /storage/music/rock /storage/music/rock_links'
StandardOutput=tty

[Install]
WantedBy=multi-user.target

Enabling mount and services

systemctl enable storage-music.mount
systemctl enable storage-music-rock.mount
systemctl enable catalog-music-rock.service

Glassfish 2.1: Using Local EJB interface in WAR's POJO

Base interface for local and remote interfaces

public interface HelloEjb extends Serializable {
  public String hello(); 
}

Define local interface

@Local
public interface HelloEjbLocal extends HelloEjb {
}

Define remote interface

@Remote
public interface HelloEjbRemote extends HelloEjb {
}

Define EJB implementation

//@Local(HelloEjbLocal.class) // not needed
//@Remote(HelloEjbRemote.class) // not needed
@Stateless
public class HelloEjbImpl extends HelloEjbLocal, HelloEjbRemote {
  public String hello() { return "hello world!"; }
}

Using EJB in POJO

Please note that the POJO must be called from a class that is part of the WAR (either servlet, webservice, etc.)

// Notes: POJO must be called by class from the WAR
@EJB(name="helloEjbJndi", beanInterface=HelloEjbLocal.class)
public class HelloClient {

  public HelloEjb getEjb() throws NamingException {
    final InitialContext ctx = new InitialContext();
    return (HelloEjb)ctx.lookup("java:comp/env/helloEjbJndi");
  }
}

Read time and battery status from bluetooth device

Pair with the device

[root@laptop ~]$ bluetoothctl 
[NEW] Controller AA:BB:CC:DD:EE:FF laptop [default]
[bluetooth]# power on
Changing power on succeeded
[bluetooth]# scan on
Discovery started
[CHG] Controller AA:BB:CC:DD:EE:FF Discovering: yes
[NEW] Device F1:F2:F3:F4:F5:F6 CHRONOS ECO XXXX
[bluetooth]# info F1:F2:F3:F4:F5:F6
Device F1:F2:F3:F4:F5:F6
 Name: CHRONOS ECO XXXX
 Alias: CHRONOS ECO XXXX
 Appearance: 0x1234
 Paired: no
 Trusted: no
 Blocked: no
 Connected: no
 LegacyPairing: no
 UUID: Vendor specific           (6e400001-b5a3-f393-e0a9-e50e24dcca9e)
[bluetooth]# trust F1:F2:F3:F4:F5:F6
[CHG] Device F1:F2:F3:F4:F5:F6 Trusted: yes
Changing F1:F2:F3:F4:F5:F6 trust succeeded
[bluetooth]# agent on
Agent registered
[bluetooth]# default-agent
Default agent request successful
[bluetooth]# pair F1:F2:F3:F4:F5:F6
Attempting to pair with F1:F2:F3:F4:F5:F6
[CHG] Device F1:F2:F3:F4:F5:F6 Connected: yes
[CHG] Device F1:F2:F3:F4:F5:F6 UUIDs:
 00001800-0000-1000-8000-00805f9b34fb
 00001801-0000-1000-8000-00805f9b34fb
 00001805-0000-1000-8000-00805f9b34fb
 0000180a-0000-1000-8000-00805f9b34fb
 0000180f-0000-1000-8000-00805f9b34fb
 6e400001-b5a3-f393-e0a9-e50e24dcca9e
[CHG] Device F1:F2:F3:F4:F5:F6 Paired: yes
Pairing successful
[bluetooth]# paired-devices 
Device F1:F2:F3:F4:F5:F6 CHRONOS ECO XXXX
[bluetooth]# info F1:F2:F3:F4:F5:F6
Device F1:F2:F3:F4:F5:F6
 Name: CHRONOS ECO XXXX
 Alias: CHRONOS ECO XXXX
 Appearance: 0x1234
 Paired: yes
 Trusted: yes
 Blocked: no
 Connected: no
 LegacyPairing: no
 UUID: Generic Access Profile    (00001800-0000-1000-8000-00805f9b34fb)
 UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
 UUID: Current Time Service      (00001805-0000-1000-8000-00805f9b34fb)
 UUID: Device Information        (0000180a-0000-1000-8000-00805f9b34fb)
 UUID: Battery Service           (0000180f-0000-1000-8000-00805f9b34fb)
 UUID: Vendor specific           (6e400001-b5a3-f393-e0a9-e50e24dcca9e)
[bluetooth]# quit

We will read the information from the "Current Time Service" and "Battery Service"

Connect to the device and list services with handles

[root@laptop ~]$ gatttool -t random -I -b F1:F2:F3:F4:F5:F6
[F1:F2:F3:F4:F5:F6][LE]> connect
Attempting to connect to F1:F2:F3:F4:F5:F6
Connection successful
[F1:F2:F3:F4:F5:F6][LE]> primary
attr handle: 0x0001, end grp handle: 0x0007 uuid: 00001800-0000-1000-8000-00805f9b34fb
attr handle: 0x0008, end grp handle: 0x000b uuid: 00001801-0000-1000-8000-00805f9b34fb
attr handle: 0x000c, end grp handle: 0x0011 uuid: 6e400001-b5a3-f393-e0a9-e50e24dcca9e
attr handle: 0x0012, end grp handle: 0x0015 uuid: 0000180f-0000-1000-8000-00805f9b34fb
attr handle: 0x0016, end grp handle: 0x0020 uuid: 0000180a-0000-1000-8000-00805f9b34fb
attr handle: 0x0021, end grp handle: 0xffff uuid: 00001805-0000-1000-8000-00805f9b34fb

Connect to handle of "Current Time Service" (00001805-0000-1000-8000-00805f9b34fb).

Use the handle and the grp handle values.

[F1:F2:F3:F4:F5:F6][LE]> characteristics 0x0021 0xffff
handle: 0x0022, char properties: 0x12, char value handle: 0x0023, uuid: 00002a2b-0000-1000-8000-00805f9b34fb

Note the "char value handle" and use it for reading characteristics data.

[F1:F2:F3:F4:F5:F6][LE]> char-read-hnd 0x0023
Characteristic value/descriptor: df 07 04 1A 16 0e 00 00 03 00 00 00 

the first two bytes are the year: 07df = 2015
the thrid byte is the month: 04 = April
the fourth byte is the date: 1A = 26
the fifth byte is the hour: 16 = 22
the sixth byte is the minutes: 0e = 14
So the date is: 26.April.2015 22:14
More information about the format could be found here

Now let's read the battery status from Battery Service (0000180f-0000-1000-8000-00805f9b34fb)

[F1:F2:F3:F4:F5:F6][LE]> characteristics 0x0012 0x0015
handle: 0x0013, char properties: 0x12, char value handle: 0x0014, uuid: 00002a19-0000-1000-8000-00805f9b34fb
[F1:F2:F3:F4:F5:F6][LE]> char-read-hnd 0x0014
Characteristic value/descriptor: 5a

This is the battery status (in percentage): 5a = 90
So the battery level is 90%.
More information about the format could be found here

Bluetooth COM port in Linux

Following tools are needed for dealing with bluetooth devices in Linux: bluetoothctl, hcitool, rfcomm, minicom

Pairing

Powering the bluetooth adapter and making it pairable

user@workstation:~$ bluetoothctl
[bluetooth]# power on
Changing power on succeeded

[bluetooth]# pairable on 
Changing pairable on succeeded

Search for new bluetooth devices - note the btaddress of the device (00:06:66:04:9E:4A). It is needed for all bluetooth commands

[bluetooth]# scan on
Discovery started
[CHG] Controller aa:bb:cc:dd:ee:ff Discovering: yes
[NEW] Device 00:06:66:04:9E:4A FireFly-9E4A

[bluetooth]# scan off
Discovery stopped
[CHG] Controller aa:bb:cc:dd:ee:ff Discovering: no

Retrieve some information about the device

[bluetooth]# info 00:06:66:04:9E:4A
Device 00:06:66:04:9E:4A
 Name: FireFly-9E4A
 Alias: FireFly-9E4A
 Class: 0x001f00
 Paired: no
 Trusted: no
 Blocked: no
 Connected: no
 LegacyPairing: yes

Optionally configure the device to be trusted - so if it automatically accepts generated PINs. However for legacy pairing manually entered PIN is required.

[bluetooth]# trust 00:06:66:04:9E:4A
[CHG] Device 00:06:66:04:9E:4A Trusted: yes
Changing 00:06:66:04:9E:4A trust succeeded

Configure the bluetoothctl to be default agent for dealing with PIN code.

[bluetooth]# agent on
Agent registered

[bluetooth]# default-agent 
Default agent request successful

Now pair with the device

[bluetooth]# pair 00:06:66:04:9E:4A
Attempting to pair with 00:06:66:04:9E:4A
[CHG] Device 00:06:66:04:9E:4A Connected: yes
Request PIN code
[agent] Enter PIN code: 1234
[CHG] Device 00:06:66:04:9E:4A UUIDs:
 00001101-0000-1000-8000-00805f9b34fb
[CHG] Device 00:06:66:04:9E:4A Paired: yes
Pairing successful

Double check the pairing and quit

[bluetooth]# paired-devices 
Device 00:06:66:04:9E:4A FireFly-9E4A

[bluetooth]# quit

Discovering services and RFCOMM channels

For devices that support SDP - Service Discovery Protocol (UUID: 00000001-0000-1000-8000-00805F9B34FB) the following command will show available protocols and RFCOMM channels. The XX:XX:XX:XX:XX:XX is the btaddress of the device. Note that in the previos example the device 00:06:66:04:9E:4A do not support SDP protocol, so the sdptool command will produce empty result.

user@workstation:~$ sdptool browse XX:XX:XX:XX:XX:XX
Service Name: Object Push Profile
Service RecHandle: 0x1000f
Service Class ID List:
  "OBEX Object Push" (0x1105)
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 2
  "OBEX" (0x0008)
Profile Descriptor List:
  "OBEX Object Push" (0x1105)
    Version: 0x0100

Creating links to the remote COM port

Retrieving the bluetooth adapter name on the local machine.

user@workstation:~$ hcitool dev
Devices
        hci0    aa:bb:cc:dd:ee:ff

The adapter is called hci0 Optionally the connection could be tested with the following command

user@workstation:~$ sudo rfcomm connect hci0 00:06:66:04:9E:4A 1

Creating symlink to bluetooth serial port

user@workstation:~$ sudo rfcomm bind hci0 00:06:66:04:9E:4A 1

Verifying that the connection is established

user@workstation:~$ sudo rfcomm -a
rfcomm0: 00:06:66:04:9E:4A channel 1 connected [tty-attached]

The serial (COM) port is available as /dev/rcomm0 Any terminal program can use it. With following command will configure rootooth bluetooth device to communicate with Roomba 520 at baud rate 115200

user@workstation:~$ sudo minicom -D /dev/rfcomm0
$$$
>CMD
U,115K,N
>AOK
---
>END

Removing the symlink

In order to remove the symbolic link to the serial port the following command must be executed:

user@workstation:~$ sudo rfcomm release hci0

Unpairing the device and removing pairing configuration

user@workstation:~$ bluetoothctl

[bluetooth]# disconnect 00:06:66:04:9E:4A
Attempting to disconnect from 00:06:66:04:9E:4A
Successful disconnected

[bluetooth]# remove 00:06:66:04:9E:4A
[DEL] Device 00:06:66:04:9E:4A FireFly-9E4A
Device has been removed

[bluetooth]# power off
Changing power off succeeded

Jenkins deployment script with VPN establishment and SSH port forwarding

Here is a deployment script that can be run from Jenkins.
It establishes VPN connections, creates SSH tunnels and copies the WAR file to remote server. At the end the WAR is verified and a deployment script is executed.

The 192.168.0.2 is the server that gives access to other machines. The target tomcat server is 192.168.0.3, but it can be accessed only from 192.168.0.2.
The deploy.sh is responsible to stop tomcat server, delete the old artifact and start the tomcat server.

#!/bin/bash
now="$(date +'%Y%m%d%H%M')"

yes | cp /opt/hudson/jobs/WAR/lastSuccessful/archive/target/app.war ./app.war

cksumline=`cksum ./app.war`

fileChkSum=$(echo "$cksumline" | awk '{print $1}')
fileSize=$(echo "$cksumline" | awk '{print $2}')

#echo "Local Checksum:$fileChkSum"
#echo "Local FileSize:$fileSize"

sudo pon vpn-conn1
echo VPN connected
sleep 10

echo Creating tunnel
sshpass -p $pass ssh -f -o ExitOnForwardFailure=yes -o StrictHostKeyChecking=no user@192.168.0.2 -L 1234:192.168.0.3:22 'sleep 30' &
sleep 10
echo Tunnel created


echo Copyng WAR file...
sshpass -p $pass scp -oStrictHostKeyChecking=no -P 1234 ./app.war user@localhost:webapps/app.war.$now
echo WAR file copied.

cksumline2=`sshpass -p $pass ssh -oStrictHostKeyChecking=no -p 1234 user@localhost cksum webapps/app.war.$now`
echo "Checksum execution on remote machine: $cksumline2"




fileChkSum2=$(echo "$cksumline2" | awk '{print $1}')
fileSize2=$(echo "$cksumline2" | awk '{print $2}')

if [[ "$fileChkSum" != "$fileChkSum2" ]]; then
  echo "Checksum differs! local: $fileChkSum, remote: $fileChkSum2"
  sudo poff vpn-conn1
  echo VPN disconnected
  exit -1
fi

if [[ "$fileSize" != "$fileSize2" ]]; then
  echo "Size differs! local: $fileSize, remote: $fileSize2"
  sudo poff vpn-conn1
  echo VPN disconnected
  exit -1
fi


sshpass -p $pass ssh -oStrictHostKeyChecking=no -p 1234 user@localhost cp webapps/app.war.$now webapps/app.war
sshpass -p $pass ssh -oStrictHostKeyChecking=no -p 1234 user@localhost ./deploy.sh


sudo poff vpn-conn1
echo VPN disconnected

Resizing VirtualBox HDD

Original post from here https://forums.virtualbox.org/viewtopic.php?f=35&t=50661

Steps:

1. Resize the Virutalbox HDD VBoxManage modifyhd <absolute path to file> --resize <size in MB>>
2. Use GParted liveCD to resize the partition http://sourceforge.net/projects/gparted/

Reverse proxy with apache

Creating reverse proxy with appache is quite easy. The common scenario is that you want to redirect entire domain to internal application server. Steps: 1) install apache 2) Edit APACHE_HOME/conf/httpd.conf with following content:

Listen 80
#Listen 1080

LogLevel debug
#ProxyHTMLLogVerbose On

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule authz_core_module modules/mod_authz_core.so
LoadModule xml2enc_module modules/mod_xml2enc.so
LoadModule proxy_html_module modules/mod_proxy_html.so
LoadModule deflate_module modules/mod_deflate.so

<VirtualHost *>
 ProxyRequests OFF
 ProxyPreserveHost On
 
 ProxyPass / ajp://127.0.0.1:8009/
 ProxyPassReverse / ajp://127.0.0.1:8009/

 #ProxyPass /app/ ajp://127.0.0.1:8009/app/
 #ProxyPass /app/ ajp://127.0.0.1:8009/app/
 #ProxyHTMLURLMap  / /app/ 

</VirtualHost>

3) On the application server (Tomcat/JBoss) deploy your app in the root context. For JBoss use jboss-web.xml with following content:

<?xml version="1.0" encoding="UTF-8"?>
<jboss-web>
<context-root>/</context-root>
</jboss-web>

Also do not forget to disable the default root application from JBOSS_HOME/standalone/configuration/ set enable-welcome-root to false

<virtual-server name="default-host" enable-welcome-root="false">

UPS under Linux

The following steps are tested on Fedora 20, but generally should work on every other system with few modifications.

Step1. Install NUT

yum install nut*

Step2. Configure UPS

Execute

nut-scanner

It should output something like this:

[nutdev1]
driver = "blazer_usb"
port = "auto"
vendorid = "0001"
productid = "0000"
product = "STD UPS MON V1.0"
bus = "006"

Add the nut-scanner output to the end of /etc/ups/ups.conf file. You can change the [nutdev1] to something more meaningful e.g. [myUps1] or [InformGuardUPS]. In the examples bellow we will use the default name [nutdev1].

Change /etc/ups/upsd.conf and add "LISTEN 127.0.0.1 3493" (without quotes)

Change /etc/ups/upsd.users and add a new admin user

[admin]
password = mypassword
actions = SET
instcmds = ALL

Change /etc/ups/upsmon.conf and add following lines:

RUN_AS_USER root
MONITOR nutdev1@localhost 1 admin mypassword master

Step3. Manually test everything

upsdrvctl start

The command should output something similar to:

Network UPS Tools - Generic HID driver 0.34 (2.4.1)
USB communication driver 0.31
Using subdriver: MGE HID 1.12
Detected EATON - Ellipse MAX 1100 [ADKK22008]

If you face a problem like "libusb couldn't open usb device /dev/usb/XXXXXX: permission denied", then use google to find a way how to solve it nicely. I used very brutal method:

chmod -R 777 /dev/bus/usb/

Then try to start UPS driver again Start the upsd:

upsd

And the result should be similar to:

Network UPS Tools upsd 2.4.1
listening on 127.0.0.1 port 3493
listening on ::1 port 3493
Connected to UPS [eaton]: usbhid-ups-eaton

List your ups names with

upsc -L

Try to query the UPS status with.

upsc nutdev1@localhost

or just

upsc nutdev1

Depending on your UPS capabilities it should return various variables and their values. See http://www.networkupstools.org/docs/user-manual.chunked/apcs01.html for more details. If you want to check if is it working on battery right now execute

upsc nutdev1 ups.status

and the output should be OL (online) or OB (on battery), LB (low battery), etc. You can also play around with some of the UPS commands/settings

upscmd nutdev1 beeper.toggle

After that reboot the system (or stop all daemons)

Step4. Starts UPS daemons automatically

Execute following commands:

systemctl enable nut-server
systemctl start nut-server
systemctl enable nut-monitor.service
systemctl start nut-monitor.service

Restart the system, and if check if everything is ok, by executing the UPS status with upsc command. Now the UPS monitoring system is configured and in case of power loss, the computer will shutdown, when the UPS battery is low. If you don't want to shutdown the computer before the 'battery low' signal follow proceed with the step

Step5. Fine tuning

This step is optional, but gives you more control over the UPS events handling. If you want to trunoff the computer before the low battery signal, then use following steps:
1. Edit /etc/ups/upsmon.conf and add following lines:

NOTIFYCMD /usr/sbin/upssched
NOTIFYFLAG ONLINE     EXEC
NOTIFYFLAG ONBATT     EXEC
NOTIFYFLAG LOWBATT    EXEC
NOTIFYFLAG FSD        EXEC
NOTIFYFLAG COMMOK     EXEC
NOTIFYFLAG COMMBAD    EXEC
NOTIFYFLAG SHUTDOWN   EXEC
NOTIFYFLAG REPLBATT   EXEC
NOTIFYFLAG NOCOMM     EXEC
NOTIFYFLAG NOPARENT   EXEC

2. Edit /etc/ups/upssched.conf and add following lines (it will allow you shutdown the computer after 15 seconds, after working on battery)

PIPEFN /var/run/nut/upssched.pipe
LOCKFN /var/run/nut/upssched.pipe
AT ONBATT * START-TIMER executeShutdown 15
AT ONLINE * CANCEL-TIMER executeShutdown
AT ONBATT * EXECUTE onBattery
AT ONLINE * EXECUTE onLine
AT NOCOMM * EXECUTE noComm
AT COMMBAD * EXECUTE commBad
AT COMMOK * EXECUTE commOk

3. Edit /usr/bin/upssched-cmd (see the exact file name from /usr/bin/upssched-cmd variable CMDSCRIPT) and add executeShutdown section similar to:

case $1 in
        upsgone)
                logger -t upssched-cmd "The UPS has been gone for awhile"
                ;;
        executeShutdown)
                shutdown -h now
                ;;
        onBattery)
                logger -t upssched-cmd "UPS is on battery!"
                ;;
        onLine)
                logger -t upssched-cmd "UPS is back online!"
                ;;
        noComm)
                logger -t upssched-cmd "No communication with the UPS device"
                ;;
        commBad)
                logger -t upssched-cmd "Communication with UPS device lost"
                ;;
        commOk)
                logger -t upssched-cmd "Communication with UPS device restored"
                ;;
        *)
                logger -t upssched-cmd "Unrecognized command: $1"
                ;;
esac

PermGen space leaks

The causes of PermGen space leaks:

1. Thread left running after web-app undeployment - the context class loader of the thread is usually the class loader of the web application, so it contains all webapp classes.
   
2. Using ThreadLocal with thread created by the web server - web app class is assigned to web server thread (e.g. HTTP worker thread) - the web app class holds a reference to the classloader, even if the web app is undeployed.
   
3. Database driver leak - every database driver should register in  java.sql.DriverManager
   the web-app must deregister it from the there, otherwise it hold a reference to the web-app class loader, if the web app is undeploye

Fedora 20 remote desktop (vncserver)

In order to enable VNC access to Fedora 20 you must install vino

yum install vino

gsettings list-recursively org.gnome.Vino

Will give you all available vino configurations Not all VNC clients supports encrypted connections, so you may need to disable it.

gsettings set org.gnome.Vino require-encryption false

Also disable the prompt when somebody tries to connect

gsettings set org.gnome.Vino prompt-enabled false

Login in gnome shell go to Settings > Share and enable Screen sharing

Establishing VPN connection under Linux

Installation

You need to install the package

sudo apt-get install pptp-linux

Configuration

Create new VPN connection:

sudo pptpsetup --create <tunnel> --server <my-vpn-server-ip> --username <vpn-user-name> --encrypt

Create routing for the connection - you need to create a new file in the directory /etc/ppp/ip-up.d/ that contains the route. The content of the file should looks similar to:

#!/bin/bash

# This script is called with the following arguments:
# Arg Name
# $1 Interface name
# $2 The tty
# $3 The link speed
# $4 Local IP number
# $5 Peer IP number
# $6 Optional ``ipparam'' value foo

ip route add 10.42.0.0/16 dev $1

You can take a look of the parameters in /etc/ppp/ip-up script

Establishing connection

sudo pon <tunnel>

Disconnecting

sudo poff <tunnel>

Debugging issues

Start the connection in debug mode

sudo pon <tunnel> debug dump logfd 2 nodetach

Show pon/poff log:

sudo plog

Manually adding route

sudo ip route add 10.42.0.0/16 dev ppp0

Adding new user from shell

To add new use execute following commands:

Creates the new user

sudo adduser <username>

Add the user to existing group

sudo usermod -aG <groupname> <username>

Create new group

sudo addgroup <groupname>

F19 post installation steps

Gnome shell 3

Tweak tool

Install gnome-tweak-tool

sudo yum install gnome-tweak-tool

Then start it, go to Desktop and enable "Have file manager handle the desktop" Go to Shell and select "Show date in clock", and for "Arrangement of buttons on the titlebar" choose "All"

Themes

sudo yum install gnome-shell-extension-user-theme.noarch

sudo yum install gnome-themes

Then logout, login start gnome-tweak-tool go to Themes tab and select Crux for "Icon theme". Go to Shell extensions and enable "User themes". Close and open the gnome-tweak-tool. Now under Theme tab you have the "Shell theme" enabled.

Nautilus

Show hidden files

gsettings set org.gnome.nautilus.preferences show-hidden-files true

Show address bar instead of buttons for file path

gsettings set org.gnome.nautilus.preferences always-use-location-entry true

Ask what to do with executable files

gsettings set org.gnome.nautilus.preferences executable-text-activation 'ask'

Configuration

Admin rights

Add sudo capabilities to current user:

usermod -a -G wheel MY_USER

Transparent terminal

sudo yum install terminator

Grub theme

sudo yum install grub2-starfield-theme

Open /etc/default/grub file sudo gedit /etc/default/grub Make entry in /etc/default grub GRUB_THEME="/boot/grub2/themes/starfield/theme.txt" Update grub sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Additional software

RPMfusion repos

Go to http://rpmfusion.org/ and download corresponding version

Music player - XMMS

sudo yum install xmms xmms-faad2 xmms-mp3 xmms-pulse xmms-skins

Video players

mplayyer

sudo yum install mplayer gecko-mediaplayer mplayer-gui mencoder

VLC

sudo yum install vlc

Error occurred during initialization of VM java/lang/NoClassDefFoundError: java/lang/Object

C:\>java -version
Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object

First thing is to find out which java is used

c:\>where java.exe
C:\Windows\System32\java.exe

Ok this is the java wrapper that reads the registry and sets the JAVA_HOME from there. Open registry editor and go to the keys (replace 1.7 with the latest major version) HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\1.7 HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\1.7.0_17

Change the JavaHome to point to correct path.
Currently it is pointing to C:\Program Files\java\jre7. Alternativly you can use C:\Program Files\java\jdk1.7.0_17\jre
You can create a java.reg file and import it into registry.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\1.7]

"JavaHome"="C:\\Program Files\\Java\\jdk1.7.0_17\\jre"

In my case the problem was faulty installation of the JRE.
I have two options:

1. either live with alternative path C:\Program Files\java\jdk1.7.0_17\jre
2. I can repair the JRE installation.

I choose option 2, so I copied everything from C:\Program Files\Java\jdk1.7.0_17\jre to C:\Program Files\java\jre7 (overriding the files).

Toplink throws NullPointerException in method _toplink.getXXX_vh()

If you persist JPA entities from another JVM sometimes Toplink throws very strange exception like:

Caused by: javax.persistence.EntityExistsException: 
Exception Description: The method [_toplink_getscore_vh] on the object [com.mycompany.data.GameEntity] triggered an exception.
Internal Exception: java.lang.reflect.InvocationTargetException
Target Invocation Exception: java.lang.NullPointerException
Mapping: oracle.toplink.essentials.mappings.OneToOneMapping[score]
Descriptor: RelationalDescriptor(com.mycompany.data.GameEntity --> [DatabaseTable(GAME_TABLE)])
 at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:224)
 at com.sun.enterprise.util.EntityManagerWrapper.persist(EntityManagerWrapper.java:440)
 at com.mycompany.MyEjbBean.create(MyEjbBean.java:1647)
 ... 26 more
Caused by: Exception [TOPLINK-99] (Oracle TopLink Essentials - 2.1 (Build b31g-fcs (10/19/2009))): oracle.toplink.essentials.exceptions.DescriptorException
Exception Description: The method [_toplink_getscore_vh] on the object [com.mycompany.data.GameEntity] triggered an exception.
Internal Exception: java.lang.reflect.InvocationTargetException
Target Invocation Exception: java.lang.NullPointerException
 at oracle.toplink.essentials.exceptions.DescriptorException.targetInvocationWhileGettingValueThruMethodAccessor(DescriptorException.java:1598)
 at oracle.toplink.essentials.internal.descriptors.MethodAttributeAccessor.getAttributeValueFromObject(MethodAttributeAccessor.java:98)
 at oracle.toplink.essentials.mappings.DatabaseMapping.getAttributeValueFromObject(DatabaseMapping.java:372)
 at oracle.toplink.essentials.mappings.ForeignReferenceMapping.getAttributeValueFromObject(ForeignReferenceMapping.java:322)
 at oracle.toplink.essentials.mappings.ObjectReferenceMapping.cascadeRegisterNewIfRequired(ObjectReferenceMapping.java:676)
 at oracle.toplink.essentials.internal.descriptors.ObjectBuilder.cascadeRegisterNewForCreate(ObjectBuilder.java:1294)
 at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:3228)
 at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:221)
 ... 28 more
Caused by: java.lang.reflect.InvocationTargetException
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at oracle.toplink.essentials.internal.security.PrivilegedAccessHelper.invokeMethod(PrivilegedAccessHelper.java:322)
 at oracle.toplink.essentials.internal.descriptors.MethodAttributeAccessor.getAttributeValueFromObject(MethodAttributeAccessor.java:91)
 ... 34 more
Caused by: java.lang.NullPointerException
 at com.mycompany.data.GameEntity._toplink_getscore_vh(GameEntity.java)
 ... 40 more
javax.ejb.EJBException: nested exception is: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
 java.rmi.RemoteException: null; nested exception is: 
 java.lang.RuntimeException: 
 at com.mycompany._MyEjbBean_Wrapper.create(com/mycompany/_MyEjbBean_Wrapper.java)
 at com.mycompany.GameTest.testGameScores(GameTest.java:62)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
 at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
 at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
 at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
 at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
 at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
 at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

The solution I found is to change the score property to be eager "@ManyToOne(fetch = FetchType.EAGER)" What I belive happens beneath is that Toplink uses bytecode to creates some additional methods for entity classes - see oracle.toplink.essentials.internal.weaving.TopLinkClassWeaver. For each field that is in relation, Toplink creates a new method called _toplink.getFIELDNAME_vh() and a class field called _toplink.getFIELDNAME_vh. VH stands for ValueHolder. I guess this additional methods/fields are used for fetching related objects later. If you examine the exception more closely it is thrown from inside _toplink.getscore_vh() which according to the javadoc in TopLinkClassWeaver should looks like:

public WeavedAttributeValueHolderInterface _toplink_getscore_vh(){
  if (_toplink_score_vh.isCoordinatedWithProperty() || _toplink_score_vh.isNewlyWeavedValueHolder()){
    EntityC object = getScore();
    if (object != _toplink_score_vh.getValue()){
      setScore(object);
    }
  }
  return _toplink_score_vh;
}

Obviously the only way to throw an exception is if _toplink_score_vh is null which after debuging is confirmed to be null. My guess is that because this is entity is transferred from another JVM (the JUnit test) and you are persisting it inside server JVM the value of _toplink_score_vh is not correctly transfered, which causes the above exception. I didn't dig up too much into the problem but the solution I found is - just make the field (in my case the "score") eager and the exception will go away.

Forget to add administrators group to SQL server 2008

Yep shit happens...
If you forget to add the administrator group (or at least the current user) to admin groups, and do not know the SA password then you have only two options
- reinstall SQL server
- use single-user-mode to add the accounts

Ok now the single-user-mode procedure.
0) login with Administrator (exactly the Administrator user, with another administrator account there will be problems)
1) open services.msc
2) go the "SQL Server (xxx)" service and stop it
3) open "Sql server configuration manager" from the start menu and make sure that the protocols "Shared memory", "Named pipes", "TCP/IP" are enabled
4) Go back to the services console right click "SQL Server (xxx)" and select properties and then enter "-m" as parameter. Click start
5) Now the server is started in single-user mode
6) Open command prompt and execute following command "sqlcmd -S \ -E", where -S specifies server and instance name, -E specifies to use windows credentials

sqlcmd -S MYMACHINE\SQLEXPRESS -E

7) Execute following commands for each windows account that you want to add

CREATE LOGIN [MYMACHINE\Administrator] FROM WINDOWS
GO
exec sp_addsrvrolemember @loginame='MYMACHINE\Administrator', @rolename = 'sysadmin' 
GO

8) Stop the SQL service and restart it without -m parameter.
9) Now you are able to log-in with Administrator user and you do have administrator rights on SQL server

Using older Java on Windows

When JDK 7 is installed it became the default java on the machine. However if you try to set different JDK (by JAVA_HOME and PATH variables) it won't change. The reason is that there is a c:\windows\system32\java.exe wrapper that reads the system registry and executes the java. If you try to change
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\CurrentVersion to 1.6 you will get the following error:

C:\Windows\System32>java -help
Error: Registry key 'Software\JavaSoft\Java Runtime Environment'\CurrentVersion'

has value '1.6', but '1.7' is required.
Error: could not find java.dll
Error: Could not find Java SE Runtime Environment.

I found two solutions on this problem:
1) use -version:1.6 as parameter

java -version:1.6 -jar myprogram.jar

It will run the jar with version 1.6
Of course you can set it into some system property like JAVA_OPT (for tomcat)

2) Add JAVA_HOME environment variable, and put %JAVA_HOME%\bin before %SystemRoot%\system32.
So the JAVA_HOME\bin\java.exe will be found before the c:\windows\system32\java.exe wrapper.