192.168.1.___ basically is reserved. Here's a blurb on
it (go to
www.iana.org for more info):
Special-Use Addresses
Several address ranges are reserved for "Special Use".
These addresses all have restrictions of some sort placed
on their use, and in general should not appear in normal
use on the public Internet. The following briefly
documents these addresses - in general they are used in
specialized technical contexts. They are described in
more detail in RFC 3330.
"Private Use" IP addresses:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
The above address blocks are reserved for use on private
networks, and should never appear in the public Internet.
There are hundreds of thousands of such private networks
(for example home firewalls sometimes make use of them).
The IANA has no record of who uses these address blocks.
Anyone may use these address blocks within their own
network without any prior notification to IANA.
The point of private address space is to allow many
organizations in different places to use the same
addresses, and as long as these disconnected or self-
contained islands of IP-speaking computers (private
intranets) are not connected, there is no problem. If you
see an apparent attack, or spam, coming from one of these
address ranges, then either it is coming from your local
environment, or the address has been "spoofed".
The Private addresses are documented in RFC 1918. If you
have further questions about RFC 1918 usage, please
contact your ISP.
"Autoconfiguration" IP Addresses:
169.254.0.0 - 169.254.255.255
Addresses in the range 169.254.0.0 to 169.254.255.255 are
used automatically by some PCs and Macs when they are
configured to use IP, do not have a static IP Address
assigned, and are unable to obtain an IP address using
DHCP.
This traffic is intended to be confined to the local
network, so the administrator of the local network should
look for misconfigured hosts. Some ISPs inadvertently
also permit this traffic, so you may also want to contact
your ISP. This is documented in RFC 3330.
"Loopback" IP addresses:
127.0.0.0 - 127.255.255.255
Each computer on the Internet uses 127.0.0.0/8 to
identify itself, to itself. 127.0.0.0 to 127.255.255.255
is earmarked for what is called "loopback". This
construct allows a computer to establish/validate its IP
stack. Most software only uses 127.0.0.1 for loopback
purposes (the other addresses in this range are seldom
used). All of the addresses within the loopback address
are treated with the same levels of restriction in
Internet routing, so it is difficult to use any other
addresses within this block for anything other than node
specific applications, generally bootstraping. This is
documented in RFC 3330.
"Unallocated" IP addresses:
The IPv4 Address Registry and the Whois use the word
unallocated (sometimes "reserved") to mean that the
addresses are reserved for future allocation. No one
should be using these addresses now. These addresses will
be assigned for use in the public Internet in the future.
If addresses are needed for private networks then the
private-use addresses mentioned above should be used.
Multicast IP addresses:
224.0.0.0 - 239.255.255.255
Addresses in the range 224.0.0.0 to 239.255.255.255 are
set aside for the special purpose of providing multicast
services in the Internet. (Multicast services allow a
computer to send a single message to many destinations.)
Various addresses in this range are used by routers and
others are used by hosts that are listening to multicast
sessions.
These addresses are available for any host that wants to
participate in multicast, and typically are assigned
dynamically. The source address should not be multicast
(without prior agreement). The destination address may be
multicast. For technical background information please
see RFC 1112 and RFC 2236.
