PostgreSQL offers data types to store IPv4, IPv6, and MAC addresses, as shown in Table 8.21. It is better to use these types instead of plain text types to store network addresses, because these types offer input error checking and specialized operators and functions (see Section 9.12).
Table 8.21. Network Address Types
| Name | Storage Size | Description | 
|---|---|---|
| cidr | 7 or 19 bytes | IPv4 and IPv6 networks | 
| inet | 7 or 19 bytes | IPv4 and IPv6 hosts and networks | 
| macaddr | 6 bytes | MAC addresses | 
| macaddr8 | 8 bytes | MAC addresses (EUI-64 format) | 
    When sorting inet or cidr data types,
    IPv4 addresses will always sort before IPv6 addresses, including
    IPv4 addresses encapsulated or mapped to IPv6 addresses, such as
    ::10.2.3.4 or ::ffff:10.4.3.2.
   
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.  Note that if you
     want to accept only networks, you should use the
     cidr type rather than inet.
    
      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 omitted, the
      netmask is taken to be 32 for IPv4 or 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.
    
cidr #
     The cidr type holds an IPv4 or IPv6 network specification.
     Input and output formats follow Classless Internet Domain Routing
     conventions.
     The format for specifying networks is address/y where address is the network's lowest
     address 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.  It is an error to specify a network address
     that has bits set to the right of the specified netmask.
    
Table 8.22 shows some examples.
Table 8.22. cidr Type Input Examples
| cidrInput | cidrOutput |  | 
|---|---|---|
| 192.168.100.128/25 | 192.168.100.128/25 | 192.168.100.128/25 | 
| 192.168/24 | 192.168.0.0/24 | 192.168.0/24 | 
| 192.168/25 | 192.168.0.0/25 | 192.168.0.0/25 | 
| 192.168.1 | 192.168.1.0/24 | 192.168.1/24 | 
| 192.168 | 192.168.0.0/24 | 192.168.0/24 | 
| 128.1 | 128.1.0.0/16 | 128.1/16 | 
| 128 | 128.0.0.0/16 | 128.0/16 | 
| 128.1.2 | 128.1.2.0/24 | 128.1.2/24 | 
| 10.1.2 | 10.1.2.0/24 | 10.1.2/24 | 
| 10.1 | 10.1.0.0/16 | 10.1/16 | 
| 10 | 10.0.0.0/8 | 10/8 | 
| 10.1.2.3/32 | 10.1.2.3/32 | 10.1.2.3/32 | 
| 2001:4f8:3:ba::/64 | 2001:4f8:3:ba::/64 | 2001:4f8:3:ba/64 | 
| 2001:4f8:3:ba:2e0:81ff:fe22:d1f1/128 | 2001:4f8:3:ba:2e0:81ff:fe22:d1f1/128 | 2001:4f8:3:ba:2e0:81ff:fe22:d1f1/128 | 
| ::ffff:1.2.3.0/120 | ::ffff:1.2.3.0/120 | ::ffff:1.2.3/120 | 
| ::ffff:1.2.3.0/128 | ::ffff:1.2.3.0/128 | ::ffff:1.2.3.0/128 | 
inet vs. cidr #
    The essential difference between inet and cidr
    data types is that inet accepts values with nonzero bits to
    the right of the netmask, whereas cidr does not.  For
    example, 192.168.0.1/24 is valid for inet
    but not for cidr.
    
        If you do not like the output format for inet or
        cidr values, try the functions host,
        text, and abbrev.
        
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' | 
| '0800-2b01-0203' | 
| '08002b010203' | 
     These examples all specify the same address.  Upper and
     lower case is accepted for the digits
     a through f.  Output is always in the
     first of the forms shown.
    
IEEE Standard 802-2001 specifies the second form shown (with hyphens) as the canonical form for MAC addresses, and specifies the first form (with colons) as used with bit-reversed, MSB-first notation, so that 08-00-2b-01-02-03 = 10:00:D4:80:40:C0. This convention is widely ignored nowadays, and it is relevant only for obsolete network protocols (such as Token Ring). PostgreSQL makes no provisions for bit reversal; all accepted formats use the canonical LSB order.
The remaining five input formats are not part of any standard.
macaddr8 #
     The macaddr8 type stores MAC addresses in EUI-64
     format, known for example from Ethernet card hardware addresses
     (although MAC addresses are used for other purposes as well).
     This type can accept both 6 and 8 byte length MAC addresses
     and stores them in 8 byte length format.  MAC addresses given
     in 6 byte format will be stored in 8 byte length format with the
     4th and 5th bytes set to FF and FE, respectively.
     Note that IPv6 uses a modified EUI-64 format where the 7th bit
     should be set to one after the conversion from EUI-48.  The
     function macaddr8_set7bit is provided to make this
     change.
     Generally speaking, any input which is comprised of pairs of hex
     digits (on byte boundaries), optionally separated consistently by
     one of ':', '-' or '.', is
     accepted.  The number of hex digits must be either 16 (8 bytes) or
     12 (6 bytes).  Leading and trailing whitespace is ignored.
     The following are examples of input formats that are accepted:
     
| '08:00:2b:01:02:03:04:05' | 
| '08-00-2b-01-02-03-04-05' | 
| '08002b:0102030405' | 
| '08002b-0102030405' | 
| '0800.2b01.0203.0405' | 
| '0800-2b01-0203-0405' | 
| '08002b01:02030405' | 
| '08002b0102030405' | 
     These examples all specify the same address.  Upper and
     lower case is accepted for the digits
     a through f.  Output is always in the
     first of the forms shown.
    
The last six input formats shown above are not part of any standard.
     To convert a traditional 48 bit MAC address in EUI-48 format to
     modified EUI-64 format to be included as the host portion of an
     IPv6 address, use macaddr8_set7bit as shown:
SELECT macaddr8_set7bit('08:00:2b:01:02:03');
    macaddr8_set7bit
-------------------------
 0a:00:2b:ff:fe:01:02:03
(1 row)