Network Address Types

cidr

The cidr type (Classless Inter-Domain Routing) holds an IPv4 or IPv6 network specification. The format for specifying networks is address/y where address is the network represented as an IPv4 or IPv6 address, and y is the number of bits in the netmask. If y is omitted, it is calculated using assumptions from the older classful network numbering system, except it will be at least large enough to include all of the octets written in the input.

• Example 1: Convert a value in the CIDR format to an IP address segment.

  For example, 10.0.0.0/8 is converted into a 32-bit binary address 00001010.00000000.00000000.00000000. /8 indicates an 8-bit network ID. The first eight bits of the 32-bit binary address are fixed. The corresponding network segment is 00001010.00000000.00000000.00000000-00001010.11111111.11111111.11111111. 10.0.0.0/8 indicates that the subnet mask is 255.0.0.0 and the corresponding network segment is 10.0.0.0-10.255.255.255.

• Example 2: Convert an IP address segment to the CIDR format.

  For the IP address segment 192.168.0.0–192.168.31.255, the last two segments can be converted into a binary address 00000000.00000000-00011111.11111111. The first 19 bits (8 x 2 + 3) are fixed. Therefore, the binary address is 192.168.0.0/19.

inet

The inet type holds an IPv4 or IPv6 host address, and optionally its subnet, all in one field. The subnet is represented by the number of network address bits present in the host address (the "netmask"). If the netmask is 32 and the address is IPv4, then the value does not indicate a subnet, only a single host. In IPv6, the address length is 128 bits, so 128 bits specify a unique host address.

The input format for this type is address/y where address is an IPv4 or IPv6 address and y is the number of bits in the netmask. If the /y portion is missing, the netmask is 32 for IPv4 and 128 for IPv6, so the value represents just a single host. On display, the /y portion is suppressed if the netmask specifies a single host.

The essential difference between the inet and cidr data types is that inet accepts values with nonzero bits to the right of the netmask, whereas cidr does not.

macaddr

The macaddr type stores MAC addresses, known for example from Ethernet card hardware addresses (although MAC addresses are used for other purposes as well). Input is accepted in the following formats:

'08:00:2b:01:02:03'
'08-00-2b-01-02-03'
'08002b:010203'
'08002b-010203'
'0800.2b01.0203'
'08002b010203'

These examples would all specify the same address. Upper and lower cases are accepted for the digits a through f. Output is always in the first of the forms shown.