Archive for June, 2011

Before performing an upgrade, you should make sure the server’s installed software and hardware support Windows Server 2008. You can download tools for testing compatibility and documentation at the Windows Server Catalog Web site (http://www.windowsservercatalog.com/).

 

Microsoft Server operating systems from Windows 2000 and later can be upgraded to Windows Server 2008. In general, servers can be upgraded to a product with equal or greater capabilities, thus:

 

  • Windows Server 2003 Standard or Enterprise editions can be upgraded to Standard or Enterprise editions of Windows Server 2008.
  • Windows Server 2003, Datacenter Edition, can be upgraded to Windows Server 2008 Datacenter.
  • Windows Server 2003, Web Edition, can be upgraded Windows Web Server 2008.
  • Windows Server 2008 Standard can be upgraded to Enterprise or Datacenter editions of Windows Server 2008.
  • Windows Server 2008 Enterprise can be upgraded to Windows Server 2008 Datacenter.
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The core function of DHCP is to assign addresses. DHCP functions at the Application Layer of the Open System Interconnection (OSI) reference model, as defined by the International Organization for Standardization (ISO) and the Telecommunication Standards Section of the International Telecommunications Union (ITU-T).

The OSI model is used for reference and teaching purposes; it divides computer networking functions into seven layers. From top to bottom, the seven layers are application, presentation,

session, transport, network, data-link, and physical

 

In brief, DHCP provides four key benefits to those managing and maintaining a TCP/IP network:

 

  • Centralized administration of IP configuration—DHCP IP configuration information can be stored in a single location and enables the administrator to centrally manage all IP configuration information. A DHCP server tracks all leased and reserved IP addresses and lists them in the DHCP console. You can use the DHCP console to determine the IP addresses of all DHCP-enabled devices on your network. Without DHCP, not only would you need to manually assign addresses, you would also need to devise a method of tracking and updating them.
  • Dynamic host configuration—DHCP automates the host configuration process for key configuration parameters. This eliminates the need to manually configure individual hosts when TCP/IP is first deployed or when IP infrastructure changes are required.
  • Seamless IP host configuration—the use of DHCP ensures that DHCP clients get accurate and timely IP configuration parameters, such as the IP address, subnet mask, default gateway, IP address of the DNS server, and so on, without user intervention. Because the configuration is automatic, troubleshooting of misconfigurations, such as mistyped numbers, is largely eliminated.
  • Flexibility and scalability—Using DHCP gives the administrator increased flexibility, allowing the administrator to more easily change IP configurations when the infrastructure changes. DHCP also scales from small to large networks. DHCP can service networks with ten clients as well as networks with thousands of clients. For very small, isolated networks, Automatic Private IP Addressing (APIPA) can be used.

A firewall is an important component of a larger overall security strategy. Windows 7 comes with a built-in firewall that’s turned on and working from the moment you first start your computer.

 

The firewall is automatically configured to prevent unsolicited Internet traffic from getting into your computer, thereby protecting you from worms and other hack attempts. The 7 firewall also provides advanced options for professional network and security administrators who need more granular control over its behavior. In Detail:

 

  • Exceptions in Windows Firewall are programs that are allowed to work through the firewall.
  • A firewall will not protect your computer from viruses, pop-up ads, or junk e-mail.
  • A firewall protects your computer from unsolicited network traffic, which is a major cause of worms and other hack attempts.
  • When you start an Internet program that needs access to the Internet through a closed port, you’ll be given a security alert with options to Unblock, or Keep Blocking, the port. You must choose Unblock to use that program.
  • Windows Firewall is one of the programs in the Security Center. To open Security Center, click the Start button and choose Control Panel ➪ Security ➪ Security Center.
  • You don’t need to configure the firewall to use standard Internet services such as the Web and e-mail. Those will work through the firewall automatically.
  • Professional network and security administrators can configure Windows Firewall through the Windows Firewall with Advanced Security console in Administrative Tools.
  • From the Start menu, you can search on the keyword fire to get to Windows Firewall configuration options.

It’s important to understand that a firewall alone is not sufficient protection against all Internet threats.

A firewall is just one component in a larger defense system. Specifically:

 

  • Windows firewall doesn’t protect you from spyware and viruses. See Chapter 8 for more information on that protection.
  • Windows firewall doesn’t protect you from attacks based on exploits. Automatic updates provide that protection.
  • A firewall doesn’t protect you from pop-up ads.
  • A firewall doesn’t protect you from phishing scams.
  • Windows firewall doesn’t protect you from spam (junk e-mail).

 

So, a firewall isn’t a complete solution. Rather, it’s an important component of a larger security strategy.

To understand what a firewall is, you need to first understand what a network connection is. Even though you have only one skinny set of wires connecting your computer to the Internet (through a phone line or cable outlet), that connection actually consists of 65,535 ports. Each port can simultaneously carry on its own conversation with the outside world. So, theoretically, you could have 65,535 things going on at a time. Of course, nobody ever has that much going on all at one time. A handful of ports are more like it.

The ports are divided into two categories: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). TCP is generally used to send text and pictures (Web pages and e-mail), and includes some error checking to make sure all the information that’s received by a computer matches what the sending computer sent. UDP works more like broadcast TV or radio, where the information is just sent out and there is no error checking. UDP is generally used for real-time communications, such as voice conversations and radio broadcasts sent over the Internet.

Each port has two directions: incoming and outgoing. The direction is in relation to stuff coming into your computer from the outside: namely the Internet. It’s the stuff coming into your computer that you have to watch out for. But you can’t close all ports to all incoming traffic. If you did, there’d be no way to get the good stuff in. But you don’t want to let everything in.

Antispyware and antivirus software are good tools for keeping out viruses and other bad things that are attached to files coming into your computer. But hackers can actually sneak worms and other bad things in through unprotected ports without involving a file in the process. That’s where the firewall comes into play. A stateful firewall, such as the one that comes with Windows 7, keeps track of everything you request. When traffic from the Internet wants to come in through a port, the firewall checks to make sure the traffic is something you requested. If it isn’t, the firewall assumes this is a hacker trying to sneak something in without your knowing it, and therefore prevents the traffic from entering your computer.


This is commonly referred to as the Blue Screen of Death (BSOD). It doesn’t mean your computer is permanently broken. A frequent cause of this problem is a device driver that doesn’t work with Windows 7.

 

If you recently connected or installed a new hardware device, disconnect or uninstall it. Then start the computer again. That’s your best bet. If you still get the Blue Screen of Death, you’ll likely have to boot to Safe Mode and disable the device through Device Manager. This is not the sort of thing the average user normally does. This is more the kind of thing that a professional would handle.

 

If the error persists, look for an error number on the Blue Screen of Death page. It will most likely start with the characters 0x. Jot that number down on a sheet of paper. Then, if you can get online through another computer, go to Microsoft’s sites (http://search.microsoft.com or http://search.microsoft.com) or your favorite online search site (such as Google) and search for that number. You might find a page that offers an exact solution to that problem.

 

If you can get online through another computer, you might also consider posting a question at the Windows Communities site. Be sure to include the error number in your post. You might find someone who has already experienced and solved that very problem.

Windows Server 2008 provides several categories of events that you can audit, as described in the following list:

 

■ Account Logon Events:  Track user logon and logoff via a user account.

■ Account Management:  Track when a user account or group is created, changed, or

deleted; a user account is renamed, enabled, or disabled; or a password is set or changed.

■ Directory Service Access:  Track access to Active Directory.

■ Logon Events:  Track nonlocal authentication events such as network use of a resource or a remote

service that is logging on by using the local system account.

■ Object Access:  Track when objects are accessed and the type of access performed—for example,

track use of a folder, file, or printer. Configure auditing of specific events through the object’s

properties (such as the Security tab for a folder or file).

■ Policy Change:  Track changes to user rights or audit policies.

■ Privilege Use:  Track when a user exercises a right other than those associated with logon and

logoff.

■ Process Tracking:  Track events related to process execution, such as program execution.

■ System Events:  Track system events such as restart, startup, shutdown, or events that affect

system security or the security log.

A good security step to take to prevent hackers and others from making unauthorized changes to a system’s registry is to prevent remote access to a system’s registry. When a user attempts to connect to a registry remotely, Windows Server 2008 checks the ACL for the following registry key:

 

HKLM\System\ControlSet001\Control\SecurePipeServers\winreg

 

If this key is missing, all users can access the registry subject to the permissions assigned to individual keys. If the key exists, Windows Server 2008 checks the permissions on the key to determine whether or not the remote user can gain access to the registry (and levels of access). Individual keys then determine what these remote users can do with a given key. Therefore, winreg is the first line of defense, and individual key ACLs are the second line of defense. If you want to prevent all remote access to the registry, make sure you set the permissions on the winreg key accordingly.


You make data sources available to clients by creating a Data Source Name (DSN). Three types of DSNs exist:

 

> User.                    A user DSN is visible only to the user who is logged on when the DSN is created.

> System.              A system DSN is visible to all local services on a computer and all users who log on locally to the                                                       computer.

> File.                     A file DSN can be shared by all users who have the same drivers installed and who

have the necessary permissions to access the DSN. Unlike user and system DSNs, file

DSNs are stored in text files, rather than the registry.

 

The DSN identifies the data source, the driver associated with a data source, and other properties that define the interaction between the client and the data source, such as timeout, read-only mode, and so on. You use the same process to create a DSN for most database types. The exception is SQL Server, which provides a wizard for setting up a data source.

 

Defining a data source

To create a data source, you first open the ODBC Data Source Administrator. To do so, click Start _ All Programs _ Administrative Tools _ Data Sources (ODBC). In the ODBC Data Source Administrator, click the tab for the DSN type you want to create and then click Add. Select the desired data source type and click Finish. Except in the case of the SQL Server driver, ODBC prompts you for information, which varies according to the driver selected. Define settings as desired and click OK to create the DSN.

Before delving into VoIP configurations, a brief introduction with terminology is necessary:

 

  • Public Switched Telephone Network (PSTN) —PSTN is the world’s collection of interconnected public voice telephone networks. It is also known as the Plain Old Telephone Service (POTS). It is set up and managed by the government and commercial organizations. It has evolved from the early days of Alexander Graham Bell to mostly digital, circuit-switched telephone network.
  • Private branch exchange (PBX) —This is a device located within an organization that routes telephone calls to internal extensions or to the PSTN. It provides additional features such as voicemail and call-forwarding. A PBX is less expensive than connecting an external line to every telephone. Numbers within the PBX (internal numbers) can be dialed using the last few numbers of the entire phone number and without going through the PSTN. A PBX usually has more than 125 ports.
  • Key telephone system —This is used like a PBX in small offices where far fewer phones are required. Each key telephone system supports up to a hundred ports.
  • Software IP phones —These consist of a headset that plugs into the USB or serial interface of a PC. The PC needs client software that supports IP telephony.
  • Hardware IP phones —These look like regular telephone sets, but they are plugged into a LAN switch. Most IP phones get power from the switch (power over Ethernet or PoE) and encapsulate voice data into IP frames for transmission over the LAN.
  • H.323—This was approved by the International Telecommunications Union (ITU) in 1996 as a standard for multimedia and audiovisual transmission across disparate networks. In 1998, it was followed by version 2. It also includes several functions such as bandwidth management, call control, multimedia management, and interoperability between different network types. H.323 has come to be the most popular protocol for VoIP.
  • Session initiation protocol (SIP)—SIP is IETF’s standard for multimedia communication over IP networks. It is an application-layer control protocol that initiates, manages, and terminates calls between two or more terminals. It is picking up as an alternative to H.323.