Allow lists in Apache Kafka® clusters

This page explains what allow lists are and which IP address allocation methods are used to define them.

Allow list

Allow list consists of CIDRs and dedicated IP addresses you define as approved to access your cluster. You can also allow or block the DoubleCloud system services from accessing the data on your cluster.

If you define an allow list, IP addresses not added to this list can't access your cluster.

IP address allocation methods

There are two main IP address allocation methods in DoubleCloud allow lists: CIDRs and single IP addresses.

  • CIDR is a compact method for specifying IP addresses and their routing suffixes.

    You can express, for example, the IP address range from 192.168.0.1 to 192.168.0.255 by using a much shorter CIDR notation of 192.168.0.1/24, where 24 represents the Netmask (or the Subnet mask) 255.255.255.0.

    Keep in mind that an IPv4 address is 32 bits in size, so the Netmask value for a CIDR can be between 0 and 32.

    You can check the Netmask value with an external subnet calculator, if needed. For example, CIDR Subnet calculator .

  • Single IP address allows you to add one IP address to your allow list.

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