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March 24 Windows is the most secure operating system - SymantecWindows was considered to be a less secure than other operating systems by many people in the IT industry. But this perception is changing. Microsoft has done a tremendous job in increasing the security of its products in the recent past. A recent report by Symantec (no friend of Microsoft) says that Windows has fewer vulnerabilities than its other counterparts. To read more click here.
March 22 Browsing from multiple subnets through ISA ServerThe other day I was configuring ISA server 2006 to enable internet browsing. I created a new array level policy to enable DNS, HTTP and HTTPS traffic. Users were able to access the internet from the same subnet as ISA server. But users connecting from other subnets were not able to access the internet. So I checked the connectivity from the client to ISA server's network and VLAN settings. Everything was fine. Finally I checked the event log in ISA server and found that the ISA server is dropping the packets due to a suspected spoof attack. Why should requests coming from a different subnet be considered as spoof? This is because ISA server believes that requests coming from any network which does not have a direct route mentioned in its routing table are spoof. So what is the solution? Simple! Add a static route using the route add command. March 20 Memory reserve feature in Windows Server Virtualization (WSV)Let me explain this concept with the help of an example. Assume that there is a virtual machine with 1GB of allocated memory. If the memory reserve (always a percentage value) for this machine is 75% it is guaranteed to have 750MB of physical memory (RAM). I.e. while this machine is running, no paging happens for the first 750MB required by the machine. The remaining memory (250MB max as the allocation is 1GB) can be either physical memory (if it is available) or page file. This feature is useful only in software test/development environments where the availability of RAM is a major constraint but performance is not. For maximum performance 100% memory reserve is recommended. The default configuration of any virtual machine is 100% memory reserve. Today in Microsoft Virtual Server 2005 the memory reserve is always 100% and is not configurable. March 17 Re:7 Reasons to Switch to Linux(http://www.techeblog.com/index.php/tech-gadget/7-reasons-to-switch-to-linux)
March 16 Windows Server 2003 Service Pack 2 (SP2) ReleasedMicrosoft has released service pack 2 of Windows server 2003 (both 32 bit and 64 bit). It is also a service pack for Windows Xp 64 bit. So what is there in this service pack for a system administrator? I think the following are important improvements from a sys admin’s point of view Ø It’s a collection of all security patches and updates till this date of Windows server 2003 and Windows Xp x64 Ø Windows Deployment Service (WDS) is the new version of remote installation service (RIS). So no more RIS in Windows Server. WDS supports Vista and Longhorn server deployments Ø Icacls.exe This is an upgrade to Cacls.exe which sys admins have been widely using for resetting access control lists (ACL) Ø Dcdiag.exe has been improved to include more options related to DNS testing Ø Support for Wi-Fi Protected Access 2 (WPA2) http://www.microsoft.com/technet/windowsserver/sp2/top-reasons.mspx March 15 Page sharing in Windows Server virtualization (WSV)WSV allows sharing of identical pages between virtual machines running on the same hardware. That is if multiple operating systems or applications are using identical pages only one instance of the page is required. The same page would be used across operating systems or applications. The net effect is increased virtual machine density per physical machine. So a good design practice is to host maximum number of identical operating systems in a physical box. I know that the next question would be about the security of such a system. I have an answer too. This feature can be turned on or off as per your security requirements. More than that this setting is configurable on a per virtual machine. Another area of concern would be performance. Yes, you can expect some amount of degradation in performance. March 10 What’s new in Windows Server Virtualization (WSV)?Ø No VMRC. RDP will be used for remote connection to virtual machines. But BIOS would still be accessible Ø X64 guest operating systems would be supported Ø Multi core processor support within virtual machines (VM) Ø More than 32 GB of RAM per VM Ø VLAN support Ø Number of VMs per physical machine depends on the hardware capacity Minimum system requirements for Windows Server Virtualization (WSV)Ø Windows server code named Longhorn x64 edition Ø Hardware with Intel-VT or AMD-V technology. Majority of hardware available today has this feature. This feature is available in laptops also. But make sure that hardware assisted virtualization is turned on at the BIOS level Ø Hardware with Data Execution Protection (DEP) feature. In AMD and Intel based servers it is known as AMD NX bit (no execute bit) and Intel XD bit (execute disable bit) respectively. This feature should also be turned on at the BIOS level. This feature basically prevents buffer over flow type attacks by not allowing code-execution from memory locations reserved as “data only”. (Yes, there are smart ways to fool this technology as well!) What is Hyper-V?Hyper-V is the hardware assisted virtualization and is going to be part of the next version of Windows server code named as Longhorn. Hyper-V allows multiple virtual machines to run on a single piece of server hardware. This helps IT managers and system administrators to a) Reduce the number of servers they manage in a data centre b) Reduce the overall power consumption c) Reduce the total rack space required And in some cases you can save the license fee too! |
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