I noticed that internet sites were loading slowly or not at all on some systems that I had upgraded from Windows XP to clean installs of Windows 7. Pinging internet sites was fine, nslookup and dig queries all returned correct DNS resolution with no errors.

Sites such as google would load okay but larger sites like Amazon would load halfway or simply not load at all. Keep in mind these symptoms were seen on clean installs of Windows 7, and because of that malware causing these problems was thrown out of the equation.

As stated earlier all attempts to ping outside hosts worked perfectly fine. All DNS resolution was working beautifully so to dig a little further I fired up Wireshark and noticed the following:

I have a CentOS box and a Windows XP box I wanted to be able to easily switch between. Instead of using a KVM switch I decided to use Synergy to switch between two monitors.

To setup Synergy I first installed it on CentOS from the EPEL repo:

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yum install synergy-plus

For reference my systems are: xp=WindowsXP Box despina=CentOS Box (replace xp and despina with your system names) Once Synergy is installed you must configure it. First edit /etc/synergy.conf

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section: screens
xp:
despina:

end

section: links

xp:
right = despina

despina:
left = xp

end

I needed to increase the size of a virtual disk on my Dell MD3000i. The MD3000i provides the storage space for my vSphere VM’s. The interface ‘Modular Disk Storage Manager’ does not provide a way to increase the size. To increase the size you must use the SMcli.exe (command line interface) provided with the Storage Manager client.

From the computer the ‘Modular Disk Storage Manager’ is installed on, open a CMD window and change to the following directory:

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C:\Program Files\Dell\MD Storage Manager\client>

From this directory execute the following command (an explanation of the switches is below):

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smcli -n Production_Storage -c "set virtualDisk [\"virtual_disk_name\"] addCapacity=26843545600;" -p "password"

Where Production_Storage is the name of your storage array, virtual_disk_name is the name of the virtual disk to increase, 26843545600 is the amount to increase the virtual disk in bytes (in this case 25GB, use this calculator to convert from GB to Bytes: Convert GB to Bytes), and password is the password to the storage array.

Once the operation is complete you will need to extend the Datastore in vSphere.

Locate the datastore, right-click the datastore, select properties and select the ‘Increase …’ button. Next you should see a selection of available devices and the same LUN should appear, select it and click next. Vsphere should see the additional free space and upon clicking next it will expand the volume.

I had a need to create a captive portal at a customer site without installing a new piece of hardware.

I decided to create a OpenBSD VM with the following configuration to make users authenticate on the gateway before being allowed internet access.

The OpenBSD VM needs two virtual NIC’s. I configured my networking in OpenBSD as follows:

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pcn0 - 192.168.0.100
pcn1 - 192.168.0.101

The file /etc/mygate needs to have the IP of the current working gateway. Mine was:

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192.168.0.10

I had a job where I needed to place a firewall in front of a network of publicly accessible computers. I decided to use a virtual transparent firewall to protect the entire network and make no changes on the client computers. This is document describes how I did it.

First the hardware: I decided to use a Dell Poweredge 1900 with ESXi server. The server has (2) Quad Core Processors, 16GB of RAM and 3 NICs. The storage is local with 4 drives set in a RAID 5 providing 600GB of storage.

Now for the NIC setup. You can see from the below diagram the BSD Bridge is setup on vmnic0 and vmnic1, vmnic2 is reserved for management and other VM’s.