A prefix list is a set of one or more network prefixes (CIDR blocks). You can reference prefix lists to configure network rules for other network resources. This topic describes how to create a prefix list.
Prerequisites
If Resource Access Management (RAM) users are used, the RAM users are granted permissions on prefix lists. For more information, see Grant a RAM user permissions on prefix lists.
Procedure
Create a prefix list in the ECS console
Log on to the ECS console.
In the left-side navigation pane, choose .
In the upper-left corner of the top navigation bar, select a region.
On the Prefix List page, click Create Prefix List.
In the Create Prefix List dialog box, configure the parameters described in the following table.
Parameter
Description
Name
Enter a name for the prefix list.
Description
Enter a description for the prefix list. We recommend that you describe the intended purpose of the prefix list.
Address Family
Select IPv4 or IPv6. After you create a prefix list, you cannot modify its address family.
If you select IPv4, you can specify only IPv4 CIDR blocks in the entries of the prefix list.
If you select IPv6, you can specify only IPv6 CIDR blocks in the entries of the prefix list.
Max Entries
Specify the maximum number of entries in the prefix list. After you create a prefix list, you cannot modify the maximum number of entries in the prefix list.
Valid values: 1 to 200.
Entries
Specify CIDR blocks as entries for the prefix list. You can click Add Entries to add a CIDR block and enter a description for the CIDR block.
The following limits apply to entries in a prefix list:
The total number of entries cannot exceed the value set for Max Entries.
You can enter multiple CIDR blocks at a time. Separate the CIDR blocks with spaces or commas (,).
The address type of a CIDR block in each entry is determined by the Address Family parameter. You cannot combine IPv4 and IPv6 CIDR blocks in a single prefix list.
CIDR blocks within entries in a prefix list must be unique. For example, you cannot specify 192.168.1.0/24 twice in the entries of the prefix list.
You can specify an IP address. The system automatically converts the IP address to a CIDR block.
For example, if you specify 192.168.1.100, the system automatically converts the IP address to 192.168.1.100/32.
If an IPv6 CIDR block is specified, the system automatically converts it to the zero compression format.
For example, if you specify 2001:0DB8:0000:0000:0000:0000:0000:0000/32, the system converts it to 2001:db8::/32.
Click Create.
Create a prefix list by calling an API operation
Call the CreatePrefixList operation with parameters configured to create a prefix list.
What to do next
After the prefix list is created, you can perform the following operations:
Maintain the prefix list. For information about how to modify the name or entries of a prefix list, see Manage the entries in a prefix list.
Reference the prefix list. For information about how to reference a prefix list in a security group rule, see Add a security group rule.