ESXi from VMware
More companies are turning to server virtualization. If you are not already using virutalization technology in your I.T. environment, I am sure you will have to start soon. There are so many positive features to come from virtualization such as:
- Makes I.T. more eco-friendly: Running multiple servers on a single piece of hardware shrinks the needs for power and cooling.
- Puts a smile on your CFO’s face: Less hardware and power use makes your budget look pretty nice!
- Improves disaster recovery: Virtual servers do not need specific hardware to run, so a server can be back online much quicker than before. There are also tools out there (like VMotion) that allow you to move a virtual server to another physical server automagically in case of a disaster.
- Network Operation Centers get smaller: Real estate is precious. Gigantic server rooms of the past can now be a server room / offices / I.T. lounge (save room in the budget for a ping pong table!).
If you want to stay competitive in the I.T. market, you will have to learn about virtualization. Several software packages are available for free that allow you to begin your wonderous journey into the virtual realm. However, you want something that is going to give you the closest experience to an enterprise virtualization system. That’s where VMware’s ESXi package comes into play.
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Jason Virtualization esxi, free, guide, server, virtual, vmware
The DHCPLOC Utility in action
DHCP is a great tool, but it does have it’s weaknesses. If your network is not secured properly, a lot of damage can be done by adding a rogue DHCP server to the mix. Let’s say you have a DHCP server giving out an address range of 192.168.128.150.10 - 100. The DHCP scope defines your gateway and DNS servers as well. Now someone else comes along and wants a better WiFi signal in their area. They setup a Linksys WiFi device at home with no problems so how difficult can it be to install one at work? I am going to point out again that you need to practice better security to avoid problems like this. Security should be proactive, not reactive. They purchase a Linksys device and slap it into the network port with the default config. Now, not only do you have an unsecure wireless broadcasting your network traffic (I’ll rant post about that later) you have a DHCP server passing out bogus IP addresses to your clients causing them to lose connection with your network.
If you ever enter a situation like this, you need to find the rogue DHCP server as soon as possible. You could start up WireShark and sniff out the network traffic, but there is an easier way. DHCPLOC is a utility from Microsoft that allows you to send out a DHCP request and capture the DHCP offer data.
NOTE: DHCPLOC does work in Vista, but the installer does not. I downloaded the toolkit from here: Windows XP Service Pack 2 Support Tools. Then I used 7Zip to extract all the files within the MS exe archive. I then located the DHCPLOC utility and saved it to my USB drive.
To use DHCPLOC:
- Open a command prompt
- Type DHCPLOC <your IP address>
- It does not look like it’s doing anything, but it is. Just hit enter and it will show you “Type d - to discover; q - to quit; h - for help.”
- Then hit “d” on the keyboard and wait a few seconds. It will bring up all DHCP offer requests that it has found.
Once the rogue DHCP server has been found, then the real detective work begins: Finding the device on the network. I will cover how to track down IP addresses in the next post.
Jason Networking dhcp, dhcploc, find, free, guide, how, rogue
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