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# IP Address
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The [IP](/IP) address, something like 192.168.0.10, is used to address an IP endpoint. The IP address is typically used to address a single network interface card ([NIC](/NIC)). Every NIC used to communicate through IP, must have at least one IP address.
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One machine can have a lot of IP addresses, as a machine can have more than one NIC, and a NIC can have more than one IP address (however, that's not widely used).
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The IP address can be statically assigned to a NIC through system specific configuration, or dynamically assigned using [DHCP](/DHCP) or [APIPA](/APIPA).
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## IP address classes
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- 0.1.0.0 - 126.0.0.0 Class A
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- 128.0.0.0 - 191.255.0.0 Class B
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- 192.0.1.0 - 223.255.255.0 Class C
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- 224.0.0.0 - 239.255.255.255 Class D
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- 240.0.0.0 - 247.255.255.255 Class E
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## Special IP addresses
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- 127.0.0.0 - 127.255.255.255 local loopback, should never appear on the network
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- 169.254.0.0 - 169.254.255.254 link local for use with Automatic Private IP Addressing ([APIPA](/APIPA))
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- 224.0.0.0 - 239.255.255.255 multicasting [RFC1112](http://www.ietf.org/rfc/rfc1112.txt), transmission to a host group
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- 255.255.255.255 limited broadcast, send to all nodes
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## Private IP Addresses
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The following IP addresses should be used for private networks:
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- 10.0.0.0 - 10.255.255.255 private in Class A
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- 172.16.0.0 - 172.31.255.255 private in Class B
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- 192.168.0.0 - 192.168.255.255 private in Class C
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## Stupid Tricks Involving IP Addresses
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Most operating systems let you specify an IP address as an integer as opposed to the traditional dotted-quad format. For instance, the following commands are equivalent:
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```
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ping 192.168.5.1
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ping 0xc0a80501 # Hexadecimal
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ping 3232236801 # Decimal
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ping 030052002401 # Octal
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```
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## External Links
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- [RFC1166](http://www.ietf.org/rfc/rfc1166.txt) "INTERNET NUMBERS" list of assigned IP addresses is a very out-of-date list of IP address ranges. To find out to whom an IP address belongs, you can use various "WHOIS" services:
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- Asia: [Asia Pacific Network Information Centre (APNIC)](http://www.apnic.net/) [WHOIS site](http://www.apnic.net/apnic-bin/whois.pl)
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- Europe: [Réseaux IP Européens (RIPE)](http://www.ripe.net/) [WHOIS site](http://www.ripe.net/db/whois/whois.html) [Assigned IP addresses in Europe](ftp://ftp.ripe.net/ripe/stats/)
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- Latin America and Caribbean: [Latin American and Caribbean Internet Addresses Registry (LACNIC)](http://lacnic.net/en/index.html) [WHOIS site](http://lacnic.net/cgi-bin/lacnic/whois?lg=EN).
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- United States and Canada: [American Registry for Internet Numbers (ARIN)](http://www.arin.net) [WHOIS site](http://www.arin.net/whois/index.html)
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- [RFC1918](http://www.ietf.org/rfc/rfc1918.txt) Private IP addresses
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- [RFC3330](http://www.ietf.org/rfc/rfc3330.txt) Special-Use IPv4 Addresses
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- [My IP Tool](http://www.iptool.us/extensions/iptool.us) Quickly detect your local and public IP Addresses. Firefox extension.
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## Discussion
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What about IPv6? See, for example, RFC 2373. - *Guy Harris*
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---
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Imported from https://wiki.wireshark.org/IP-address on 2020-08-11 23:15:11 UTC |