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Server Load Balancer:DescribeLoadBalancerTCPListenerAttribute

Last Updated:Mar 02, 2026

Queries the configuration of a TCP listener.

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Test

RAM authorization

The table below describes the authorization required to call this API. You can define it in a Resource Access Management (RAM) policy. The table's columns are detailed below:

  • Action: The actions can be used in the Action element of RAM permission policy statements to grant permissions to perform the operation.

  • API: The API that you can call to perform the action.

  • Access level: The predefined level of access granted for each API. Valid values: create, list, get, update, and delete.

  • Resource type: The type of the resource that supports authorization to perform the action. It indicates if the action supports resource-level permission. The specified resource must be compatible with the action. Otherwise, the policy will be ineffective.

    • For APIs with resource-level permissions, required resource types are marked with an asterisk (*). Specify the corresponding Alibaba Cloud Resource Name (ARN) in the Resource element of the policy.

    • For APIs without resource-level permissions, it is shown as All Resources. Use an asterisk (*) in the Resource element of the policy.

  • Condition key: The condition keys defined by the service. The key allows for granular control, applying to either actions alone or actions associated with specific resources. In addition to service-specific condition keys, Alibaba Cloud provides a set of common condition keys applicable across all RAM-supported services.

  • Dependent action: The dependent actions required to run the action. To complete the action, the RAM user or the RAM role must have the permissions to perform all dependent actions.

Action

Access level

Resource type

Condition key

Dependent action

slb:DescribeLoadBalancerTCPListenerAttribute

get

*loadbalancer

acs:slb:{#regionId}:{#accountId}:loadbalancer/{#loadbalancerId}

  • slb:tag
  • slb:tag
  • slb:tag
  • slb:tag
  • slb:tag
None

Request parameters

Parameter

Type

Required

Description

Example

RegionId

string

No

The region ID of the Classic Load Balancer instance.

You can find the region ID in the Regions and zones list or by calling the DescribeRegions operation.

cn-hangzhou

LoadBalancerId

string

Yes

The ID of the Classic Load Balancer instance.

lb-bp1ygod3yctvg1y****

ListenerPort

integer

Yes

The frontend port used by the Classic Load Balancer instance.

Valid values: 1 to 65535.

80

Response elements

Element

Type

Description

Example

object

VServerGroupId

string

The ID of the attached vServer group.

rsp-cige6******8

Status

string

The current status of the listener. Valid values:

  • running: The listener is running normally.

  • stopped: The listener is stopped.

stopped

AclType

string

The access control type. Valid values:

  • white: Only requests from IP addresses or CIDR blocks in the specified access control policy group are forwarded. Use this option when your application allows only specific IP addresses to access it. Enabling a whitelist carries business risks. After you enable a whitelist, only IP addresses in the whitelist can access the listener.

If you enable a whitelist but do not add any IP addresses to the access control policy group, the listener forwards all requests.

  • black: Requests from IP addresses or CIDR blocks in the specified access control policy group are blocked. Use this option when your application restricts access from specific IP addresses.

If you enable a blacklist but do not add any IP addresses to the access control policy group, the listener forwards all requests.

Note

This parameter is required if the AclStatus parameter is set to on.

white

ConnectionDrainTimeout

integer

The timeout period for connection draining. This parameter is returned only if the ConnectionDrain parameter is set to on.

Valid values: 10 to 900 seconds.

300

RequestId

string

The request ID.

365F4154-92F6-4AE4-92F8-7FF34B540710

HealthCheckConnectPort

integer

The port used for health checks. Valid values: 1 to 65535. If you do not specify this parameter, the backend server port (BackendServerPort) is used.

8080

Description

string

The custom name of the listener.

TCP_80

Bandwidth

integer

The peak bandwidth of the listener, in Mbit/s. Valid values:

  • -1: For Internet-facing SLB instances that use pay-by-data-transfer billing, you can set the peak bandwidth to -1 to remove the bandwidth limit.

  • 1 to 5120: For Internet-facing SLB instances that use pay-by-bandwidth billing, you can set the peak bandwidth for each listener. However, the sum of the peak bandwidths of all listeners cannot exceed the peak bandwidth of the instance.

-1

HealthCheckType

string

The health check method for the TCP listener.

Valid values: tcp or http.

tcp

MasterSlaveServerGroupId

string

The ID of the attached primary/secondary server group.

rsp-0bfucw****

BackendServerPort

integer

The backend port used by the Classic Load Balancer instance.

Note

This parameter is not displayed if the backend server group is a vServer group.

443

AclStatus

string

Whether to enable access control. Valid values:

  • on: Enable access control.

  • off: Disable access control.

off

HealthCheckDomain

string

The domain name used for health checks. Valid values:

  • $_ip: The private IP address of the backend server. If you specify an IP address or omit this parameter, Server Load Balancer uses the private IP address of each backend server as the domain name for health checks.

  • domain: A domain name that is 1 to 80 characters in length and contains only letters, digits, periods (.), and hyphens (-).

www.domain.com

UnhealthyThreshold

integer

The unhealthy threshold. After consecutive health check failures reach this value, the health check status of a backend server changes from success to failure. Valid values: 2 to 10.

4

HealthCheckHttpCode

string

The HTTP status code that indicates a successful health check.

http_2xx

ProxyProtocolV2Enabled

boolean

Whether to enable Proxy Protocol V2 to pass client source IP addresses to backend servers. Valid values:

  • true: Enable.

  • false: Disable.

false

PersistenceTimeout

integer

The timeout period for session persistence.

Valid values: 0 to 3600 seconds. Default value: 0, which disables session persistence.

0

ListenerPort

integer

The frontend port used by the Classic Load Balancer instance.

110

HealthCheckInterval

integer

The interval between health checks. Valid values: 1 to 50 seconds.

5

HealthCheckURI

string

The URL used for health checks. The URL must be 1 to 80 characters in length and can contain only letters, digits, hyphens (-), forward slashes (/), periods (.), percent signs (%), question marks (?), number signs (#), and ampersands (&). The URL cannot be just a forward slash (/), but it must start with a forward slash (/).

/test/index.html

AclId

string

The ID of the access control policy group attached to the listener.

This parameter is required if the AclStatus parameter is set to on.

acl-uf60jwfi******

SynProxy

string

Whether to enable SynProxy attack prevention for the load balancer.

We recommend that you do not change this parameter. Let Server Load Balancer manage it.

  • enable: Enable SynProxy.

  • disable: Disable SynProxy.

disable

Scheduler

string

The scheduling algorithm. Valid values:

  • wrr (default): Backend servers with higher weights receive more requests.

  • rr: Requests are distributed to backend servers in sequence.

  • sch: Consistent hashing based on source IP addresses. Requests from the same source IP address are routed to the same backend server.

  • tch: Consistent hashing based on four-tuples (source IP address, destination IP address, source port, and destination port). Requests in the same flow are routed to the same backend server.

Note

The sch and tch algorithms are supported only by guaranteed-performance instances.

wrr

EstablishedTimeout

integer

The connection timeout period.

500

HealthCheckConnectTimeout

integer

The timeout period for health checks.

100

HealthyThreshold

integer

The healthy threshold. After consecutive health check successes reach this value, the health check status of a backend server changes from failure to success. Valid values: 2 to 10.

4

ConnectionDrain

string

Whether to enable connection draining. This parameter is returned only if the ConnectionDrain parameter is set to on. Valid values:

  • on: Enable connection draining.

  • off: Disable connection draining.

off

HealthCheckMethod

string

The health check method.

tcp

HealthCheck

string

Whether to enable health checks. Valid values:

  • on: Enable health checks.

  • off: Disable health checks.

on

AclIds

object

AclId

array

A list of access control policy group IDs.

LoadBalancerId

string

The ID of the Classic Load Balancer instance.

lb-bp1ygod3yctvg1y****

Tags

object

Tag

array<object>

A list of tags.

object

A list of tags.

TagKey

string

The tag key of the listener. Valid values of N: 1 to 20. If you specify this parameter, it cannot be an empty string. It can be up to 128 characters in length. It cannot start with aliyun or acs:. It cannot contain http:// or https://.

TestKey

TagValue

string

The tag value of the listener. Valid values of N: 1 to 20. If you specify this parameter, it can be an empty string. It can be up to 128 characters in length. It cannot start with acs:. It cannot contain http:// or https://.

TestValue

Examples

Success response

JSON format

{
  "VServerGroupId": "rsp-cige6******8",
  "Status": "stopped",
  "AclType": "white",
  "ConnectionDrainTimeout": 300,
  "RequestId": "365F4154-92F6-4AE4-92F8-7FF34B540710",
  "HealthCheckConnectPort": 8080,
  "Description": "TCP_80",
  "Bandwidth": -1,
  "HealthCheckType": "tcp",
  "MasterSlaveServerGroupId": "rsp-0bfucw****",
  "BackendServerPort": 443,
  "AclStatus": "off",
  "HealthCheckDomain": "www.domain.com",
  "UnhealthyThreshold": 4,
  "HealthCheckHttpCode": "http_2xx",
  "ProxyProtocolV2Enabled": false,
  "PersistenceTimeout": 0,
  "ListenerPort": 110,
  "HealthCheckInterval": 5,
  "HealthCheckURI": "/test/index.html",
  "AclId": "acl-uf60jwfi******",
  "SynProxy": "disable",
  "Scheduler": "wrr",
  "EstablishedTimeout": 500,
  "HealthCheckConnectTimeout": 100,
  "HealthyThreshold": 4,
  "ConnectionDrain": "off",
  "HealthCheckMethod": "tcp",
  "HealthCheck": "on",
  "AclIds": {
    "AclId": [
      ""
    ]
  },
  "LoadBalancerId": "lb-bp1ygod3yctvg1y****",
  "Tags": {
    "Tag": [
      {
        "TagKey": "TestKey",
        "TagValue": "TestValue"
      }
    ]
  }
}

Error codes

HTTP status code

Error code

Error message

Description

400 LocationServiceTimeout Location service connection timeout. Please try again later.
403 UnauthorizedRegion The specified region of is not authorized. The specified region of is not authorized.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.