> ## Documentation Index > Fetch the complete documentation index at: https://altostrat.io/docs/llms.txt > Use this file to discover all available pages before exploring further. # Create a prefix list > Creates a new prefix list with a defined set of CIDR blocks and initial site associations. Site associations and address list deployments are handled asynchronously. ## OpenAPI ````yaml /api/en/security-groups.yaml post /vpc/prefix-lists openapi: 3.0.3 info: title: Altostrat Security Groups API version: 1.0.0 description: >- The Altostrat Security Groups API is the microservice responsible for the centralized management of stateful firewall rulesets and reusable IP address collections. It serves as the source of truth for all network security policies within the Altostrat SDX platform, translating abstract rules into concrete configurations that are asynchronously deployed to MikroTik routers. This API allows you to programmatically manage: - **Security Groups:** Containers for stateful firewall rules that define allowed inbound and outbound traffic for associated network sites. - **Prefix Lists:** Reusable, named collections of IP addresses and CIDR blocks that can be referenced within Security Group rules to simplify policy management. Developers use this API to programmatically define, manage, and automate network security policies at scale across their entire MikroTik infrastructure. servers: - url: https://v1.api.altostrat.io description: Production API Server security: [] tags: - name: Security Groups description: Manage firewall rule containers and their associations with network sites. - name: Prefix Lists description: Manage reusable collections of IP addresses and CIDR blocks. - name: Reference Data description: Retrieve static data like supported protocols and services. paths: /vpc/prefix-lists: post: tags: - Prefix Lists summary: Create a prefix list description: >- Creates a new prefix list with a defined set of CIDR blocks and initial site associations. Site associations and address list deployments are handled asynchronously. operationId: createPrefixList requestBody: description: The details of the new prefix list. required: true content: application/json: schema: $ref: '#/components/schemas/PrefixListWrite' responses: '201': description: The prefix list was created successfully. content: application/json: schema: $ref: '#/components/schemas/PrefixList' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '422': $ref: '#/components/responses/UnprocessableEntity' '500': $ref: '#/components/responses/InternalServerError' security: - bearerAuth: [] components: schemas: PrefixListWrite: type: object description: Defines the writable properties for creating or updating a prefix list. required: - name - prefixes - sites properties: name: type: string maxLength: 255 description: A human-readable name for the prefix list. example: Third-Party API Endpoints description: type: string maxLength: 1000 nullable: true description: An optional description for the prefix list. example: Static IPs for services we integrate with. prefixes: type: array maxItems: 500 description: >- A list of prefixes (CIDR blocks). The entire list is replaced on update. items: $ref: '#/components/schemas/PrefixWrite' sites: type: array description: >- A list of site IDs where this prefix list should be directly applied. The entire list of sites is replaced on update. items: type: string example: site_0ujsswThIGTUYm2K8FjOOfxcYpw example: name: Corporate Office IPs description: Static IPs for our main corporate office. prefixes: - cidr: 203.0.113.0/28 description: Primary ISP Block - cidr: 198.51.100.10/32 description: Backup ISP sites: [] PrefixList: type: object description: Represents a reusable, named collection of IP addresses and CIDR blocks. properties: id: type: string description: >- The unique identifier for the prefix list, prefixed with `prfx_lst_`. readOnly: true example: prfx_lst_0ujsswThIGTUYm2K8FjOOfxcYpw name: type: string description: A human-readable name for the prefix list. example: Main Office IPs description: type: string description: An optional description for the prefix list. example: Public IP ranges for the main office. status: type: string description: The current synchronization status of the prefix list. readOnly: true enum: - active - syncing - failed example: active sites: type: array description: A list of site IDs where this prefix list is directly applied. items: type: string example: site_12345 prefixes: type: array description: The list of CIDR blocks in this prefix list. items: $ref: '#/components/schemas/Prefix' PrefixWrite: type: object description: Defines the writable properties for a prefix. required: - cidr properties: cidr: type: string description: A valid IPv4 CIDR block. example: 203.0.113.0/24 description: type: string maxLength: 500 nullable: true description: An optional description for this prefix. example: Payment provider API IPs Prefix: type: object description: Represents a single IP address or CIDR block within a prefix list. properties: id: type: string description: The unique identifier for the prefix entry, prefixed with `prfx_`. readOnly: true example: prfx_0ujsswThIGTUYm2K8FjOOfxcYpw cidr: type: string description: The IP address range in CIDR notation. example: 192.0.2.0/24 description: type: string description: An optional description for this specific prefix. example: Main server subnet ErrorResponse: type: object properties: type: type: string description: A broad category for the error (e.g., 'invalid_request_error'). example: invalid_request_error code: type: string description: A short, unique string identifying the specific error. example: parameter_missing message: type: string description: A human-readable description of what went wrong. example: The 'name' parameter is required for this request. doc_url: type: string description: >- A direct link to the documentation page for this specific error code. example: https://docs.altostrat.io/errors/parameter_missing responses: BadRequest: description: >- Bad Request - The request was malformed, for example, due to invalid JSON. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' Unauthorized: description: >- Unauthorized - The request requires authentication, and a valid Bearer token was not provided. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' UnprocessableEntity: description: >- Unprocessable Entity - The request was well-formed but was unable to be followed due to semantic errors (e.g., validation failed). content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' InternalServerError: description: Internal Server Error - An unexpected error occurred on the server. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: >- Authentication is performed via an Auth0-issued JSON Web Token (JWT). Provide the token in the `Authorization` header with the `Bearer` scheme. ````