Stop Bind from performing forward lookups using IPv6

by admin Posted on September 19, 2013

You may get logs similar to the following:
Sep 17 16:15:07 nsserver named[21089]: network unreachable resolving
'ns2.vistaprint.com/A/IN': 2001:503:a83e::2:30#53
You can specify OPTIONS=’-4′ in /etc/sysconfig/named to tell named not to use IPv6 or disable IPv6 completely on your machine. You can disable IPv6 this way:
Add
“options ipv6 disable=1” to /etc/modprobe.conf
and
“NETWORKING_IPV6=no” to /etc/sysconfig/network

Posted in Linux | Comments Off on Stop Bind from performing forward lookups using IPv6

Useful PowerCLI scripts

by admin Posted on September 13, 2013

—Find VMs with snapshots

Connect-VIServer vcenter
Get-VM | Get-Snapshot | Select Created, VM

—Find VMs with mounted ISO

Get-VM | FT Name, @{Label="ISO file"; Expression = { ($_ | Get-CDDrive).ISOPath }}

—Get Datastores and Used Storage for VMs within Cluster

Get-Cluster "Cluster_name" | Get-VM | Select Name, @{N="Datastore";E={Get-Datastore -vm $_}}, UsedSpaceGB, ProvisionedSpaceGB  | sort Name | Export-Csv C:\datastores-acceptance.csv

Disconnect all VM CD-ROM Drives

get-cddrive -VM * |where {$_.ISOPATH -ne $null}|set-cddrive  -nomedia
Posted in Virtualization | Comments Off on Useful PowerCLI scripts

Useful Linux Commands

by admin Posted on September 12, 2013

In order to add additional repositories on your Centos you have to run:

rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

This command for example will add the EPEL repository. You can find additional repositories on http://wiki.centos.org/AdditionalResources/Repositories

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Searching for packages with yum:

yum list samba

Display list of updated software:

yum list updates

Apply all updates:

yum update

Update specified package

yum update bind

Check if there is an update for a specified package:

yum list updates bind

Install network setup tool

yum install system-config-network-tui

Find which package contains a specific command

yum provides OR whatprovides ifconfig

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Using tcpdump to capture packets

tcpdump -n -i eth0 port 25

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List The Open Ports And The Process That Owns Them

netstat -tulpn
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Killing a Windows service that’s stuck on stopping or starting

by admin Posted on September 9, 2013

If you ever have trouble with a service being stuck in a ‘starting’ or ‘stopping’ state, you can run a couple of simple commands to kill the service.

–First query the process to find it’s PID:

sc queryex |more

–Kill the process:

taskkill /f /pid 3386
Posted in Windows | Comments Off on Killing a Windows service that’s stuck on stopping or starting

Install VMware Tools on Centos

by admin Posted on April 20, 2013

Firstly we have to install some prerequisites:

yum install make gcc kernel-devel kernel-headers glibc-headers perl

Mount the VMware Tools CD

mkdir /mnt/cdrom
mount /dev/cdrom /mnt/cdrom

Copy the install bundle from the CD and extract it

cp /mnt/cdrom/VMware-Tools*.tar.gz /tmp/
cd /tmp/
tar xvfz VMwareTools*.tar.gz

Run The installer

cd /tmp/vmware-tools-distrib
./vmware-install.pl
Posted in Virtualization | Leave a comment

Copy Share permissions from one folder to another

by admin Posted on April 19, 2013

To copy share permissions from one shared folder to another you have to use the permcopy command which is included in Windows Resource Kit Tools:

permcopy \\SourceServer Sharename \\Destinationserver Sharename

This command will copy the share permissions but not the security permissions of a folder. In order to copy the security permissions (and the files and folders included within it) I personally use the robocopy command which is also included in Windows Resource Kit Tools:

robocopy \\Source \\Destination /MIR /SEC /r:3 /w:5
Posted in Windows | Comments Off on Copy Share permissions from one folder to another

Useful Excel formulas

by admin Posted on April 18, 2013

In this article I will post some excel formulas that I have used and might need again sometime. From time to time I might edit this post and add additional formulas.

  • Find duplicate entries in a range of cells

Select the range of cells you want to check –>Format –>Conditional Formating –>Formula is – add the formula

=IF(COUNTIF($A1:$A$1;$A1)-1>0;TRUE;FALSE)

Press Format and change the formating for these cells

  • Find cells that do not have exactly 12 digits

Select the range of cells you want to check –>Format –>Conditional Formating –>Formula is – add the formula =LEN(B1)<>12

Press Format and change the formating for these cells

 

Posted in Windows | Comments Off on Useful Excel formulas

Esxi – Virtual NIC to Physical NIC mapping

by admin Posted on April 18, 2013

In order to determine which physical NIC a virtual NIC of a VM is using, we have to login to the Host and use the esxtop utility. In the default esxtop screen we have to press “n” in order to get the network “view”. The results will have the following fields:

Virtual machine —– Physical NIC —- vSwitch —- various metrics

 

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Multiple RDP Sessions in Windows Server 2008 R2

by admin Posted on April 18, 2013

In order to allow multiple concurrent sessions on Windows Server 2008 R2 you have to perform the following steps:

– Start -> Administrator Tools -> Remote Desktop Services -> Remote Desktop Services Host Configuration
– Double click the “Remote Desktop Licensing Mode” under the “Licensing” Title
– Uncheck the default behaviour of “Restrict each user to a single session”.

Now you can connect with 2 clients to the same machine without loosing your session.

Posted in Windows | Comments Off on Multiple RDP Sessions in Windows Server 2008 R2