Setting up SNMP V3 on CentOS

Posted on July 31, 2015 by admin

Install SNMP.

yum install net-snmp net-snmp-utils

Configure the SNMP V3 user by running the following command and then following the prompts it gives you.

net-snmp-create-v3-user

Example: The username is “snmpadmin” and the password is”r123456″

[root@localhost ~]# net-snmp-create-v3-user
Enter a SNMPv3 user name to create:
snmpadmin
Enter authentication pass-phrase:
r123456
Enter encryption pass-phrase:
  [press return to reuse the authentication pass-phrase]

adding the following line to /var/lib/net-snmp/snmpd.conf:
   createUser snmpadmin MD5 "r123456" DES
adding the following line to /etc/snmp/snmpd.conf:
   rwuser snmpadmin
[root@localhost ~]#

Change the syslocation and syscontact in the /etc/snmp/snmpd.conf file.

vi /etc/snmp/snmpd.conf

Start snmpd service

service snmpd start

Configure snmp to start on system boot.

chkconfig snmpd on

Test and make sure snmp is working

replace “password” and “username” with the ones you setup when you created the SNMP V3 user.

snmpwalk -v3 -a MD5 -A password -x DES -X password -l authPriv -u privuser localhost

If you receive something like “snmpwalk: Timeout” then something is not working correctly. Check to make sure the service is started, and make sure that your firewall is not blocking SNMP.

If you are running a firewall, run the following commands to allow it through.

firewall-cmd --zone=public --add-port=161/udp --permanent
semanage port -a -t snmp_port_t -p udp 161
firewall-cmd --reload

On iptables you should be able to do

 iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 161 -j ACCEPT

or add it to /etc/sysconfig/iptables and then restart iptables

Increase hard disk size on Windows VM in XenServer

Posted on July 24, 2015 by admin

To increase a Windows VM disk size you’ll first need to shut down the VM and then increase the disk size from XenCenter. When you boot back up into the VM, the extra space shows up as unallocated. All that needs to be done is the main partition needs to be extended.

Open up the Windows Disk Management Utility. You can do this by clicking on the start button, typing in disk management and hit enter. This will bring up the Disk Management program.

In disk manager, you should see the Unallocated space at the end of Disk 0, i.e. your main drive. Right click on your main partition (C:) and click Extend Volume. You will be presented with a wizard that will walk you through extending your disk.

Example:

Before increasing the VM’s disk size.

The unallocated space is the extra space that we added via XenCenter. Right click on the middle partition (C:), and click extend.

After were are finished extending the partition, we see that our main partition is about 8GB larger.

How to setup a Planets3 Alpha Multiplayer Server

Posted on July 23, 2015 by admin

Prerequisite:

Windows computer/server that has a public IP address
Planets3Alpha downloaded to the above computer (The Server is included in the Windows Planets3 Alpha download)

Installing Planets3 Alpha

Installing Planets3 Alpha is easy to do. Run the installer and follow the prompts. The server gets installed when you install the Planets3 Alpha, you just have to launch the server file to run the server.

Setting up Firewall

Click on the Start button type in firewall and hit enter. This should start up the Windows Firewall application.

What we need to do is create a new inbound rule to allow UDP port 7777 (the Planets3 server port) so we can connect to the server.

Click on Inbound Rules, and then Create a New Rule…

Select Port.

Select “UDP” and “Specific local ports:” The port number is 7777

Give the New Rule a Name and Description.

And finally click Finish.

Configure Planets3Alpha to Start on System Log In

You can manually launch the server by double clicking on the “start_server” file under “C:\Program Files (x86)\Planets3Alpha\”

If you want to have Planets3 Startup on system log in, do the following.

Open up the Planets3 install directory in Windows Explorer, it should be under “C:\Program Files (x86)\Planets3Alpha\”. Create a shortcut by right clicking on “start_server” then Create shortcut. Now drag the shortcut to the Startup folder found under All Programs in the start menu.

That’s it. You should be able to reboot, log in, and have Planets3 Alpha multiplayer server start automatically. All that is left is for you to connect to your new server.

How To Create a Clonezilla Boot Drive

Posted on July 23, 2015 by admin

Format USB Drive as FAT32
Download the Clonezilla Live zip here or from Clonzilla’s website.
Extract the zip, and copy the contents to the root of your USB drive
Run the appropriate version of makeboot. “H:\” is you usb drive. Change if necessary.
1. 64bit is under “H:\utils\win64\makeboot64.bat”
2. 32bit is under “H:\utils\win32\makeboot.bat”
  1. Make sure you are running makeboot.bat from the USB drive and NOT you local C: drive.
Follow the prompts and when it is finished try to boot from it.

How to add extra space to Linux VM in XenServer

Posted on July 23, 2015 by admin

Before we start you will need to do the following in XenCenter

Shutdown the VM
Increase the virtual hard drive size of the Linux VM
Boot the VM back up

Before starting any of the following, it is a good idea to backup any data you would not want to lose. You should not lose any data following these steps, but there is always the possibility for something to go wrong.

What is going to happen

Delete the main partition. We are going to recreate it.
Create a new partition that starts on the same boundary as the previous partition
Write changes to disk and reboot
Resize the Disk
Check that everything went well

The path to the disk is “/dev/xvda” the LVM path/name is “/dev/VolGroup/lv_root” The goal is to increase lv_root’s size from about 8GB to about 12GB. If for some reason your drive is not “xvda” or your LVM name is different, change the commands accordingly.

Here are the commands in a nutshell.

fdisk /dev/xvda                        <-- Edit the Partition Table
reboot                                 <-- Reboot to apply the partition table updates
pvdisplay                              <-- Display Physical Volume info
pvresize /dev/xvda2                    <-- Resize Physical Volume
lvresize /dev/xvda2 -l +100%FREE       <-- Resize Logical Volume
resize2fs /dev/VolGroup/lv_root        <-- Resize File System

Example:

You may be able to substitute all the fdisk commands with
`parted /dev/xvda resizepart 2 100%`
Change 2 for the actual partition you need to resize.

All the keys and command that were hit and executed are in bold.

[root@localhost ~]# fdisk /dev/xvda

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p

Disk /dev/xvda: 12.9 GB, 12884901888 bytes
255 heads, 63 sectors/track, 1566 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00066ace

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/xvda2              64        1045     7875584   8e  Linux LVM
Command (m for help): d
Partition number (1-4): 2

Command (m for help): p

Disk /dev/xvda: 12.9 GB, 12884901888 bytes
255 heads, 63 sectors/track, 1566 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00066ace

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (64-1566, default 64): 
Command (m for help): p

Disk /dev/xvda: 12.9 GB, 12884901888 bytes
255 heads, 63 sectors/track, 1566 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00066ace

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/xvda2              64        1566    12065871   83  Linux

Command (m for help): wq
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root@localhost ~]# reboot

Show the current size of the Physical Volume

pvdisplay

[root@localhost ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/xvda2
  VG Name               VolGroup
  PV Size               7.51 GiB / not usable 3.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              1922
  Free PE               0
  Allocated PE          1922
  PV UUID               zKmGEt-Uf0A-I14h-NDYc-53rf-micT-VxNqsP
   
[root@localhost ~]#

Resize the Physical Volume

pvresize /dev/xvda2

[root@localhost ~]# pvresize /dev/xvda2
  Physical volume "/dev/xvda2" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized
[root@localhost ~]#

Run pvdisplay again. You should see more space under PV Size.

[root@localhost ~]# pvdisplay
  --- Physical volume ---
  PV Name               /dev/xvda2
  VG Name               VolGroup
  PV Size               11.51 GiB / not usable 2.08 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              2945
  Free PE               1023
  Allocated PE          1922
  PV UUID               zKmGEt-Uf0A-I14h-NDYc-53rf-micT-VxNqsP
   
[root@localhost ~]#

Notice the “Free PE” section above. If it says 0 then you won’t be able to run the next command.

Resize LVM

the “+100%FREE” part of the command tells it to uses up all of the free space available

lvresize /dev/VolGroup/lv_root -l +100%FREE

[root@localhost ~]# lvresize /dev/VolGroup/lv_root -l +100%FREE
  Extending logical volume lv_root to 10.71 GiB
  Logical volume lv_root successfully resized
[root@localhost ~]#

Resize the File System

resize2fs /dev/VolGroup/lv_root

[root@localhost ~]# lvresize /dev/VolGroup/lv_root -l +100%FREE
  Extending logical volume lv_root to 10.71 GiB
  Logical volume lv_root successfully resized
[root@localhost ~]#

And that is it. Check out the extra space.

[root@localhost ~]# df -h /
Filesystem                    Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root   11G  733M  9.3G   8% /
[root@localhost ~]# exit

Create a Bootable OS X Yosemite Thumb Drive – Simple Version

Posted on July 23, 2015 by admin

Open up disk utility and format your thumb drive as “Mac OS Extended (Journaled)”

Open up a terminal, and run the following command. Change “USBdrive” to your USB Drives name.

sudo /Path/to/Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/USBdrive --applicationpath /Path/to/Yosemite.app --nointeraction

Enter in your password and let it run.

Example:

sudo /Applications/Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/OSXInstaller --applicationpath /Applications/Yosemite.app --nointeraction

How to Boot a XenServer VM into Recovery Mode

Posted on July 22, 2015 by admin

Recovery Mode can be helpful if you need to do certain task like operate on the VM with the disk unmounted or you need to reset a root password.

All of the following is done through XenCenter

To boot the VM into recovery mode all you have to do is

Shutdown the VM
Insert boot media i.e. (DVD, cd, iso image, etc.) into DVD Drive 1:
Start VM in Recovery Mode. In the main menu click on VM –> Start/Shut Down –> Start in Recovery Mode

When the VM boots up it will boot off of whatever is in DVD Drive 1.

How to Backup and Restore UniFi data from the Command Line

Posted on July 22, 2015 by admin

Backup

backup the UniFi directory

tar zcvf unifi-backup.tgz /usr/UniFi/

Move the tar archive off site.

Restore

Upload the backup file to the server.

Note: You will need to have the UniFi controller install already.

Copy the archive to the root directory and then extract it.

mv unifi-backup.tgz /
cd /
tar zxvf unifi-backup.tgz

Reboot the server and login to the UniFi controller.

reboot

Clean GPT Drive in Windows

Posted on July 15, 2015 by admin

Hit the Windows key, type in diskpart and hit enter

You should get a black Command like Prompt window.

List the disks

list disk

You should get a list of the disk you have as well as the number for the disk.

Select the disk you want in our case disk 3. Change the number to the number of your drive

select disk 3

clean the disk

clean

Now you can open up Disk Manager and create a new Simple Volume on your drive.

Set up Minecraft Server on CentOS 6

Posted on July 14, 2015 by admin

Update system

yum update -y

Install Java and wget

yum install -y java wget

Allow Minecraft port through the firewall

Insert the following line in your iptables config file, found in “/etc/sysconfig/iptables”

-A INPUT -m state --state NEW -m tcp -p tcp --dport 25565 -j ACCEPT

Example:

vi /etc/sysconfig/iptables
# Firewall configuration written by system-config-firewall
 # Manual customization of this file is not recommended.
 *filter
 :INPUT ACCEPT [0:0]
 :FORWARD ACCEPT [0:0]
 :OUTPUT ACCEPT [0:0]
 -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
 -A INPUT -p icmp -j ACCEPT
 -A INPUT -i lo -j ACCEPT
 -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
 -A INPUT -m state --state NEW -m tcp -p tcp --dport 25565 -j ACCEPT <--- Added Rule
 -A INPUT -j REJECT --reject-with icmp-host-prohibited
 -A FORWARD -j REJECT --reject-with icmp-host-prohibited
 COMMIT
 ~
 ~
 :wq
"/etc/sysconfig/iptables" 14L, 544C written
 [root@localhost ~]# service iptables restart
 iptables: Setting chains to policy ACCEPT: filter [ OK ]
 iptables: Flushing firewall rules: [ OK ]
 iptables: Unloading modules: [ OK ]
 iptables: Applying firewall rules: [ OK ]
 [root@localhost ~]#

Setup your network.

you will need to edit the network config file in “/etc/sysconfig/network-scripts/ifcfg-eth0”

DHCP

If your using DHCP then just change “ONBOOT=no” to “ONBOOT=yes”

Static

If you need a static address, then change “ONBOOT=no” to “ONBOOT=yes” and change “BOOTPROTO=dhcp” to “BOOTPROTO=static”

add the following to “/etc/sysconfig/network-scripts/ifcfg-eth0”

IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
BROADCAST=192.168.1.255
DNS1=1.1.1.1

Start Minecraft server on system boot

Create user

useradd -m steve

Create password for steve

passwd steve

su steve

Go to user root directory

cd ~/

Download the minecraft server jar

wget https://s3.amazonaws.com/Minecraft.Download/versions/1.8.7/minecraft_server.1.8.7.jar

Create a directory for the start up script and create start up script.

mkdir /home/steve/mc
touch /home/steve/mc/mcstart.sh

Copy and paste the following text into mcstart.sh

#! /bin/sh
# /etc/init.d/mcserver

### BEGIN INIT INFO
# Minecraft CraftBukkit Start script
### END INIT INFO

case "$1" in
  start)
    echo "Starting mcserver"
    MCDIR="/home/steve/"
    cd "$MCDIR"
    java -Xmx512M -jar minecraft_server.1.8.7.jar -o true &
;;
  stop)
    echo "Stopping mcserver"
    kill `pgrep mcserver`
    ;;
  *)
    echo "Usage: /etc/init.d/mcserver {start|stop}"
    exit 1
    ;;
esac
exit 0

Make the script executable

chmod +x /home/steve/mc/mcstart.sh

Add mcstart.sh to the crontab

Access the crontab by running the following command

crontab -e

Add the following to the crontab.

@reboot /home/steve/mc/mcstart.sh start

Start the server.

/home/steve/mc/mcstart.sh start

Note: Starting the server will fail because you need to agree to the end user license agreement.

Agree to the eula

sed -i s/false/true/g eula.txt

Reboot the server and connect to your new Minecraft server.