Windows Vista Security: Praxisorientierte Sicherheit für Profis

Networking with TCP/IP

|

491

Networking with TCP/IP

While Windows Vista has the capability of using several networking protocols, the

primary protocols used are TCP and IP. Windows Vista uses the TCP/IP protocol for

networking among peer-to-peer networks, domain-controlled networks, and the

Internet. TCP/IP is a vital protocol set for using your operating system fully.

Windows Vista contains a new TCP/IP stack, referred to as a dual stack, that works

with IP Version 4 (IPv4) and IP Version 6 (IPv6). IPv4 uses a limited 32-bit address

space, defined by four octets and a subnet mask composed of four octets. IPv6 uses a

128-bit addressing scheme, allowing for the needed IP growth of the Internet.

Understanding IPv4

IP addresses used with IPv4 can be divided into two parts: the network ID and the

host ID. The network ID identifies the network on which a computer or device is

located and the host ID identifies the computer or device.

An example of an IPv4 address is 192.168.1.1, which shows the four distinct sets of

numbers divided by a period, or dot. Each section separated by a dot is referred to as

an octet, which correlates to an eight-bit number in binary form.

The second set of numbers associated with an IPv4 address is the subnet mask. The

subnet mask identifies which parts of the IP address belong to the network ID and

which parts belong to the host ID.

Subnet masks use four distinct octets separated by a period, or dot, just like the IP

address. Subnet masking correlates to the network ID and the actual host ID of the

computer by giving binary values of either a 1, for a bit that belongs to the network

ID, or 0, for a bit that belongs to the host ID. An example of a subnet mask is 255.0.

0.0, which is read in binary as 11111111.00000000.00000000.00000000. Thus, the

first 8 bits of the IP address belong to the network ID and the final 24 bits belong to

the host ID.

When you use standard subnet masks, you are said to be using a classful network.

Classful networks are defined in three different classes: Class A, Class B, and Class C.

Table 14-2 shows examples of the different classful networks. Table 14-3 shows net-

work ID examples, and Table 14-4 gives some examples of subnet forms translated

into binary to help you understand the differences in their formats and to differenti-

ate the network ID portion of the subnet from the host ID portion of the subnet.

Table 14-2. IPv4 subnet example

Subnet class Example Maximum nodes

Class A 255.0.0.0 16,777,214

Class B 255.255.0.0 65,534

Class C 255.255.255.0 254