Whats the difference between 10.x.x.x and 192.x.x.x

[TechBoyJK]

Are these both private address schemes that can be used for the same purposes?

 

[n0cmonkey]

An important note, its 10.0.0.0/8 and 192.168.0.0/16. There is also 172.16.0.0/12.

3. Private Address Space

The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the IP address space for private internets:

10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

From RFC 1918

EDIT: Duh, I forgot to answer the question. Yes, they can be used for the same thing. I am currently using 2 of these addresses on my home network, considering a third eventually.

 

[Santa]

There is also the Microsoft Automatic Private IP Addressing range (APIPA) of 169.254.0.1 through 169.254.255.254 with a mask of 255.255.0.0

 

[TechBoyJK]

thanks, i know that concept now.

 

[alrox]

169.254.0.0/16 is not part of the offical private address space found in rfc1918. Your windows box will assign a dhcp enabled NIC an address from that subnet when it can't contact a DHCP server. Anyone using those IP's on a permanent basis has an improperly configured network.

 

[lobadobadingdong]

192.168.0.1 is also the IP address WinXP sets when you enable internet connection sharing, kind of a pain, but if you need it it's there.

 

[PlatinumGold]

192.x.x.x is for smaller networks, 10.x.x.x is for larger networks.

 

[PlatinumGold]

There is also the Microsoft Automatic Private IP Addressing range (APIPA) of 169.254.0.1 through 169.254.255.254 with a mask of 255.255.0.0

The way i understand it, Microsoft owns this range of addresses, not private but public. it isn't in circulation and ms uses that range of addresses for apipa. basically if you get an apipa IP address ur not reaching ur dhcp server.

 

[Santa]

Correct,

It is not apart of the orginial RFC 1918 but it is a private subnet that has been recognized by the IANA as something used on a local network and to not be routed.

It is a feature of Windows 98 and up to get these IP assignments but doesn't mean you can't use it for your own Network.

You are correct in that the block ultimatly does belong to Microsoft but you won't have trouble using it locally since that is what Microsoft has allocated that block for.

http://www.microsoft.com/windowsxp/pro/using/howto/networking/autoconfig.asp

When APIPA is used, Windows XP TCP/IP uses an address in the APIPA IP address range (169.254.0.1 through 169.254.255.254) and the subnet mask is set to 255.255.0.0. The range of IP addresses (169.254.0.1 through 169.254.255.254) used for APIPA is reserved by the Internet Assigned Numbers Authority (IANA). Any IP addresses within this range are not used on the Internet.

Sorry this is offtopic slightly but thought people would find it interesting..

I am sure TechBoyJK has all the answers he wanted and then some by now

 

[TechBoyJK]

yea, i almost forgot i started the post.

 

[Buddha Bart]

fundamentaly: the number of IPs you get

[edit]Oh yeah, and 10.0.0.x is much easier to type, even if you have a really small network, right on the bottom of the number pad[/edit]

bart

 

[mobly99]

For clarification:

From RFC 3330
169.254.0.0/16 - This is the "link local" block. It is allocated for
communication between hosts on a single link. Hosts obtain these
addresses by auto-configuration, such as when a DHCP server may not
be found.

Check the ARIN whois server, you'll see that block belongs to IANA for special use, not Microsoft, nor are Microsoft the only ones who use it (they have since Windows 98), Apple has been using it as well since OS 8.

Microsoft and Apple (and Sun recently) have been colaberating on the draft for several years (the first draft was out in November 2000 ... http://www.ietf.org/internet-drafts/draft-ietf-zeroconf-ipv4-linklocal-07.txt

-Dave

 

[andrey]

Private IP addresses are defined in Internet RFC 1918. For those wishing to know more about Private IP, RFC 1918 is suggested reading. See ftp://ftp.ufl.edu/net/rfcs. The private IP adresses are the following blocks:

Class A 10.0.0.0 - 10.255.255.255
Class B 172.16.0.0 - 172.31.255.255
Class C 192.168.0.0 - 192.168.255.255

These addresses are not recognized by Internet routers. Packets with either source or destination private addresses are not forwarded across Internet links. As such these addresses can be used by machines which do not require direct connection to other hosts across the Internet. It is possible, through address translation, for some UF hosts using private IP to access a host across the Internet. The configuration of an address translator requires a pool of public IP addresses. When an IP application originating from a host with a private IP address which is destined for the Internet is opened, the address translator assigns an IP number from the address pool. Every packet related to this application aquires the assigned IP number at the translator. UF supports an IP translator for this purpose. The translator will be located near the Internet POP. Each block of IP private addresses will be labelled as translated or untranslated. Packets carrying addesses from a translated block are routed through the translator. Public addresses for the translator pool will be assigned from one of the blocks of UF public IP addresses.

I hope this helps,
--Andrey

 

[spidey07]

A little more info...

Internet routers actually can and do forward the private IP networks and routes. Many providers run their backbone and internal routing with a 10.x.x.x network. It is at the network edge where the public domain resides.

But for the most part any person configuring a border or gateway router will always put in access lists that drop packets with a source and/or destination address of the private blocks.

 

[TechBoyJK]

so, would a primary rule in a firewall config be to block all incoming packets from these private addresses? The only network traffic from these addresses that the firewall should see should be behind the firewall.

 

[n0cmonkey]

Originally posted by: TechBoyJK
so, would a primary rule in a firewall config be to block all incoming packets from these private addresses? The only network traffic from these addresses that the firewall should see should be behind the firewall.

Yes, it should be near the top of the list.

 

[spidey07]

Yes. It should be one of the first rules on a firewall.

Also you generally put some anti spoofing rules on the internet router.

Drop all RFC 1918 addresses.
Drop any source address inbound on my internet circuits that have a source address of my address block, etc.

 

[n0cmonkey]

Originally posted by: spidey07
Yes. It should be one of the first rules on a firewall.

Also you generally put some anti spoofing rules on the internet router.

Drop all RFC 1918 addresses.
Drop any source address inbound on my internet circuits that have a source address of my address block, etc.

Add in 127.0.0.0/8, (if you have any of them) unassigned ips, etc.

 

[spidey07]

Follow RFC2827 and you're all set.