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Chapter 8: Internet Information Services
and see how IIS 5 serviced requests: a single user process, called inetinfo.exe, took
care of HTTP requests and acted as the traffic director, sending the requests on to
worker processes using dllhost.exe. One problem was that inetinfo.exe operated in
user mode rather than kernel mode, which made serving a lot slower just by virtue of
where the process was residing in the OS architecture. Contrast this with IIS 6 in
Windows Server 2003, which transfers responsibility for directing HTTP requests
from a user mode process to a kernel mode driver. The speed increase just as a result
of this move is remarkable, mainly because it can interact with the hardware at a
lower, more direct level, listening for HTTP requests before Windows has to funnel
them up to user mode.
Another big benefit is the interoperability of IIS with the underlying operating sys-
tem and with Active Directory. You get seamless integration of all components,
meaning administration is simpler (you’re used to the same interfaces) and user data
and information can be shared among all the pieces of your infrastructure.
IIS is not installed by default in new installations of Windows Server 2003, unlike
previous versions. You can choose from several “subprograms” that each perform a
different service and install them as you need them. IIS is the moniker that refers to
all these services collectively. This section will highlight the individual components
and provide a bit of information about each.
The Web Server
The web server, named W3SVC, is the part of the software that makes files available
for web browsing using the HTTP protocol. You can support multiple DNS domains
on one server by using either multiple virtual servers or a feature called host headers.
Host headers examine the TCP/IP header of a web request, detect the intended desti-
nation of the packet, and route it to the appropriate process; this obviates the need
for different domains to have unique IP addresses on one machine.
The FTP Server
This component of IIS (FTPSVC) enables you to transfer files from a server to a cli-
ent. The FTP protocol dates back to the beginning of the Internet, and it’s still one of
the most efficient ways to transfer large amounts of data between hosts over a wide
area. However, FTP is inherently insecure because it transfers all data—including the
username and password for authentication purposes—in clear text.