terraform/website/docs/configuration/functions/cidrhost.html.md

layout	page_title	sidebar_current	description
functions	cidrhost - Functions - Configuration Language	docs-funcs-ipnet-cidrhost	The cidrhost function calculates a full host IP address within a given IP network address prefix.

cidrhost Function

-> Note: This page is about Terraform 0.12 and later. For Terraform 0.11 and earlier, see 0.11 Configuration Language: Interpolation Syntax.

cidrhost calculates a full host IP address for a given host number within a given IP network address prefix.

cidrhost(prefix, hostnum)

prefix must be given in CIDR notation, as defined in RFC 4632 section 3.1.

hostnum is a whole number that can be represented as a binary integer with no more than the number of digits remaining in the address after the given prefix. For more details on how this function interprets CIDR prefixes and populates host numbers, see the worked example for cidrsubnet.

Conventionally host number zero is used to represent the address of the network itself and the host number that would fill all the host bits with binary 1 represents the network's broadcast address. These numbers should generally not be used to identify individual hosts except in unusual situations, such as point-to-point links.

This function accepts both IPv6 and IPv4 prefixes, and the result always uses the same addressing scheme as the given prefix.

Examples

> cidrhost("10.12.127.0/20", 16)
10.12.112.16
> cidrhost("10.12.127.0/20", 268)
10.12.113.12
> cidrhost("fd00:fd12:3456:7890:00a2::/72", 34)
fd00:fd12:3456:7890::22

Related Functions

• cidrsubnet calculates a subnet address under a given network address prefix.