> ## Documentation Index > Fetch the complete documentation index at: https://gcore.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Assign security group > Assign the security group to the server. To assign multiple security groups to all ports, use the NULL value for the `port_id` field ## OpenAPI ````yaml /api-reference/services_documented/cloud_api.yaml post /cloud/v1/instances/{project_id}/{region_id}/{instance_id}/addsecuritygroup openapi: 3.1.0 info: title: Gcore OpenAPI – Cloud API description: >- This OpenAPI is an aggregated OpenAPI specification that unifies all Gcore products into a single file. It covers Cloud, CDN, DNS, WAAP, DDoS Protection, Object Storage, Streaming, and FastEdge services. version: '2026-05-07T20:33:46.548242+00:00' servers: - url: https://api.gcore.com security: - APIKey: [] tags: - name: Bare Metal x-displayName: Bare Metal - name: Container as a Service x-displayName: Container as a Service - name: Cost Reports x-displayName: Cost Reports - name: DDoS Protection x-displayName: DDoS Protection - name: Everywhere Inference x-displayName: Everywhere Inference - name: Everywhere Inference Apps x-displayName: Everywhere Inference Apps - name: File Shares x-displayName: File Shares - name: Floating IPs x-displayName: Floating IPs - name: Function as a Service x-displayName: Function as a Service - name: GPU Bare Metal x-displayName: GPU Bare Metal - name: GPU Virtual x-displayName: GPU Virtual - name: IP Ranges x-displayName: IP Ranges - name: Images x-displayName: Images - name: Instances x-displayName: Instances - name: Load Balancers x-displayName: Load Balancers - name: Logging x-displayName: Logging - name: Managed Kubernetes x-displayName: Managed Kubernetes - name: Managed PostgreSQL x-displayName: Managed PostgreSQL - name: Networks x-displayName: Networks - name: Placement Groups x-displayName: Placement Groups - name: Projects x-displayName: Projects - name: Quotas x-displayName: Quotas - name: Regions x-displayName: Regions - name: Registry x-displayName: Registry - name: Reservations x-displayName: Reservations - name: Reserved IPs x-displayName: Reserved IPs - name: Routers x-displayName: Routers - name: SSH Keys x-displayName: SSH Keys - name: Secrets x-displayName: Secrets - name: Security Groups x-displayName: Security Groups - name: Snapshot Schedules x-displayName: Snapshot Schedules - name: Snapshots x-displayName: Snapshots - name: Tasks x-displayName: Tasks - name: User Actions x-displayName: User Actions - name: User Role Assignments x-displayName: User Role Assignments - name: Volumes x-displayName: Volumes paths: /cloud/v1/instances/{project_id}/{region_id}/{instance_id}/addsecuritygroup: post: tags: - Instances summary: Assign security group description: >- Assign the security group to the server. To assign multiple security groups to all ports, use the NULL value for the `port_id` field operationId: InstanceAddSecurityGroupHandler.post parameters: - in: path name: project_id required: true description: Project ID schema: type: integer - in: path name: region_id required: true description: Region ID schema: type: integer - in: path name: instance_id required: true description: Instance ID schema: type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/InstancePortsSecurityGroupsSchema' responses: '204': description: Everything is OK x-codeSamples: - lang: Python source: |- import os from gcore import Gcore client = Gcore( api_key=os.environ.get("GCORE_API_KEY"), # This is the default and can be omitted ) client.cloud.instances.assign_security_group( instance_id="instance_id", project_id=0, region_id=0, ) - lang: Go source: "package main\n\nimport (\n\t\"context\"\n\n\t\"github.com/G-Core/gcore-go\"\n\t\"github.com/G-Core/gcore-go/cloud\"\n\t\"github.com/G-Core/gcore-go/option\"\n)\n\nfunc main() {\n\tclient := gcore.NewClient(\n\t\toption.WithAPIKey(\"My API Key\"),\n\t)\n\terr := client.Cloud.Instances.AssignSecurityGroup(\n\t\tcontext.TODO(),\n\t\t\"instance_id\",\n\t\tcloud.InstanceAssignSecurityGroupParams{\n\t\t\tProjectID: gcore.Int(0),\n\t\t\tRegionID: gcore.Int(0),\n\t\t},\n\t)\n\tif err != nil {\n\t\tpanic(err.Error())\n\t}\n}\n" components: schemas: InstancePortsSecurityGroupsSchema: type: object properties: name: type: string pattern: ^[a-zA-Z0-9][a-zA-Z 0-9._\-]{1,61}[a-zA-Z0-9._]$ description: Security group name, applies to all ports ports_security_group_names: type: array description: Port security groups mapping items: $ref: '#/components/schemas/PortSecurityGroupNamesSchema' description: Instance ports security groups example: name: some_name ports_security_group_names: - port_id: null security_group_names: - some_name - port_id: ee2402d0-f0cd-4503-9b75-69be1d11c5f1 security_group_names: - name1 - name2 PortSecurityGroupNamesSchema: type: object properties: port_id: type: - string - 'null' description: Port ID. If None, security groups will be applied to all ports security_group_names: type: array description: List of security group names items: pattern: ^[a-zA-Z0-9][a-zA-Z 0-9._\-]{1,61}[a-zA-Z0-9._]$ type: string required: - port_id - security_group_names description: Port security group names example: port_id: ee2402d0-f0cd-4503-9b75-69be1d11c5f1 security_group_names: - name1 - name2 securitySchemes: APIKey: description: >- API key for authentication. Make sure to include the word `apikey`, followed by a single space and then your token. Example: `apikey 1234$abcdef` type: apiKey in: header name: Authorization ````