This topic describes how to create a Destination Network Address Translation (DNAT) entry by using the Alibaba Cloud SDK for Python.

Background information

The following operations are included in the example code:
  1. Create a virtual private cloud (VPC) in the China (Shanghai) region.
  2. Create a VSwitch for the VPC.
  3. Create a NAT gateway for the VPC.
  4. Create an elastic IP address (EIP) in the China (Shanghai) region.
  5. Associate the EIP with the NAT gateway.
  6. Create a DNAT entry.
  7. Query the EIP that is associated with the NAT gateway.
  8. Query the NAT gateway.
  9. Delete the DNAT entry.
  10. Disassociate the EIP from the NAT gateway.
  11. Delete the NAT gateway.
  12. Releases the EIP.
  13. Delete the VSwitch.
  14. Delete the VPC.

Procedure

  1. In the downloaded SDK directory, open the $aliyun-openapi-python-sdk-examples\sdk_examples\examples\natgw folder.
  2. Open the natgw_snat.py file in your text editor. Set the parameters as required, save the configuration, and then exit the editor.
    The following sample code is displayed:
    #encoding=utf-8
    import sys
    import json
    import time
    
    from aliyunsdkcore.acs_exception.exceptions import ServerException, ClientException
    from aliyunsdkvpc.request.v20160428 import CreateNatGatewayRequest
    from aliyunsdkvpc.request.v20160428 import DeleteNatGatewayRequest
    from aliyunsdkvpc.request.v20160428 import DescribeNatGatewaysRequest
    from aliyunsdkvpc.request.v20160428 import CreateForwardEntryRequest
    from aliyunsdkvpc.request.v20160428 import DescribeForwardTableEntriesRequest
    from aliyunsdkvpc.request.v20160428 import DeleteForwardEntryRequest
    from sdk_lib.sdk_vpc import Vpc
    from sdk_lib.sdk_vswitch import VSwitch
    from sdk_lib.sdk_eip import Eip
    from sdk_lib.sdk_cbwp import CommonBandwidthPackage
    from sdk_lib.common_util import CommonUtil
    from sdk_lib.check_status import CheckStatus
    from sdk_lib.exception import ExceptionHandler
    from sdk_lib.consts import *
    
    client = AcsClient(
        'accessKeyId',
        'accessSecret',
        'RegionId'
        #timeout = 35
    )
    
    
    class NatGateway(object):
        def __init__(self, client):
            self.client = client
    
        def create_nat_gateway(self, params):
            """
            create_nat_gateway: creates a NAT gateway.
            """
            try:
                request = CreateNatGatewayRequest.CreateNatGatewayRequest()
                request.set_VpcId(params['vpc_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the NAT gateway is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME,
                                            self.describe_nat_gateway_status,
                                            AVAILABLE, response_json['NatGatewayId']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_nat_gateway(self, nat_gateway_id):
            """
            describe_nat_gateway: queries information about the created NAT gateway in a specified region.
            """
            try:
                request = DescribeNatGatewaysRequest.DescribeNatGatewaysRequest()
                request.set_NatGatewayId(nat_gateway_id)
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def delete_nat_gateway(self, params):
            """
            delete_nat_gateway: deletes the NAT gateway.
            """
            try:
                request = DeleteNatGatewayRequest.DeleteNatGatewayRequest()
                request.set_NatGatewayId(params['nat_gateway_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the NAT gateway is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME * 5,
                                            self.describe_nat_gateway_status,
                                            '', params['nat_gateway_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_nat_gateway_status(self, nat_gateway_id):
            """
            describe_nat_gateway_status: queries the status of created NAT gateway in a specified region.
            """
            response = self.describe_nat_gateway(nat_gateway_id)
            if len(response["NatGateways"]["NatGateway"]) == 0:
                return ''
            return response["NatGateways"]["NatGateway"][0]['Status']
    
        def create_forward_entry(self, params):
            """
            create_forward_entry: creates a forward entry.
            """
            try:
                request = CreateForwardEntryRequest.CreateForwardEntryRequest()
                request.set_ForwardTableId(params['forward_table_id'])
                request.set_ExternalIp(params['external_ip'])
                request.set_IpProtocol(params['ip_protocol'])
                request.set_ExternalPort(params['external_port'])
                request.set_InternalIp(params['internal_ip'])
                request.set_InternalPort(params['internal_port'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the forward entry is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME,
                                            self.describe_forward_status,
                                            AVAILABLE, params['forward_table_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_forward(self, forward_table_id):
            """
            describe_forward: queries the information about DNAT entries in a specified region.
            """
            try:
                request = DescribeForwardTableEntriesRequest.DescribeForwardTableEntriesRequest()
                request.set_ForwardTableId(forward_table_id)
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
        def describe_forward_status(self, forward_table_id):
            """
            describe_forward_status: queries the status of the created DNAT entries in a specified region.
            """
            response = self.describe_forward(forward_table_id)
            if len(response["ForwardTableEntries"]["ForwardTableEntry"]) == 0:
                return ''
            return response["ForwardTableEntries"]["ForwardTableEntry"][0]['Status']
    
        def delete_forward_entry(self, params):
            """
            delete_forward_entry: deletes a forward entry.
            """
            try:
                request = DeleteForwardEntryRequest.DeleteForwardEntryRequest()
                request.set_ForwardTableId(params['forward_table_id'])
                request.set_ForwardEntryId(params['forward_entry_id'])
                response = client.do_action_with_exception(request)
                response_json = json.loads(response)
                # Check whether the forward entry is in the available state.
                if CheckStatus.check_status(TIME_DEFAULT_OUT, DEFAULT_TIME * 5,
                                            self.describe_forward_status,
                                            '', params['forward_table_id']):
                    return response_json
            except ServerException as e:
                ExceptionHandler.server_exception(e)
            except ClientException as e:
                ExceptionHandler.client_exception(e)
    
    
    def main():
        vpc = Vpc(client)
        vswitch = VSwitch(client)
        eip = Eip(client)
        cbwp = CommonBandwidthPackage(client)
        nat_gateway = NatGateway(client)
    
        params = {}
    
        # Create a VPC.
        vpc_json = vpc.create_vpc()
        CommonUtil.log("create_vpc", vpc_json)
    
        # Create a VSwitch.
        params['vpc_id'] = vpc_json['VpcId']
        params['zone_id'] = "cn-hangzhou-d"
        params['cidr_block'] = "172.16.1.0/24"
        vswitch_json = vswitch.create_vswitch(params)
        CommonUtil.log("create_vswitch", vswitch_json)
        params['vswitch_id'] = vswitch_json['VSwitchId']
    
        # Create a NAT gateway.
        nat_gateway_json = nat_gateway.create_nat_gateway(params)
        CommonUtil.log("create_nat_gateway", nat_gateway_json)
    
        # Create an EIP.
        eip_response_json = eip.allocate_eip_address(params)
        CommonUtil.log("allocate_eip_address", eip_response_json)
        params['allocation_id'] = eip_response_json["AllocationId"]
        params['external_ip'] = eip_response_json['EipAddress']
    
        # Associate the EIP with the NAT gateway.
        params['instance_id'] = nat_gateway_json['NatGatewayId']
        params['allocation_id'] = eip_response_json["AllocationId"]
        params['instance_type'] = 'Nat'
        eip_response_json = eip.associate_eip_address(params)
        CommonUtil.log("associate_eip_address eip", eip_response_json)
    
        # Create a forward entry.
        params['forward_table_id'] = nat_gateway_json['ForwardTableIds']['ForwardTableId'][0]
        params['ip_protocol'] = 'tcp'
        params['external_port'] = '8080'
        params['internal_port'] = '80'
        params['internal_ip'] = '172.16.1.0'
        forward_entry_json = nat_gateway.create_forward_entry(params)
        CommonUtil.log("create_forward_entry", forward_entry_json)
    
        # Query the EIP.
        eip_response_json = eip.describe_eip_address(params['allocation_id'])
        CommonUtil.log("describe_eip_address", eip_response_json)
    
        # Query the NAT gateway.
        params['nat_gateway_id'] = nat_gateway_json['NatGatewayId']
        nat_gateway_json = nat_gateway.describe_nat_gateway(params['nat_gateway_id'])
        CommonUtil.log("describe_nat_gateway", nat_gateway_json)
    
        # Delete a forward entry.
        params['forward_entry_id'] = forward_entry_json['ForwardEntryId']
        forward_entry_json = nat_gateway.delete_forward_entry(params)
        CommonUtil.log("delete_forward_entry", forward_entry_json)
    
        # Disassociate the EIP from the NAT gateway.
        eip_response_json = eip.unassociate_eip_address(params)
        CommonUtil.log("unassociate_eip_address nat", eip_response_json)
    
        # Delete the NAT gateway.
        nat_gateway_json = nat_gateway.delete_nat_gateway(params)
        CommonUtil.log("delete_nat_gateway", nat_gateway_json)
    
        # Release the EIP.
        eip_response_json = eip.release_eip_address(params)
        CommonUtil.log("release_eip_address", eip_response_json)
    
        # Delete the VSwitch.
        params['vswitch_id'] = vswitch_json['VSwitchId']
        vswitch_json = vswitch.delete_vswitch(params)
        CommonUtil.log("delete_vswitch", vswitch_json)
    
        # Delete the VPC.
        vpc_json = vpc.delete_vpc(params)
        CommonUtil.log("delete_vpc", vpc_json)
    
    
    if __name__ == "__main__":
        sys.exit(main())
  3. Go to the directory where natgw_snat.py is located, and run the following command to create a DNAT entry:
    python natgw_dnat.py

Result

The following output is returned:
---------------------------create_vpc---------------------------
{
  "ResourceGroupId": "rg-acfmxazxxxxxxxx",
  "RouteTableId": "vtb-uf63rln6gbb50xxxxxxxx",
  "VRouterId": "vrt-uf6p1hfo0ho8gxxxxxxxx",
  "VpcId": "vpc-uf6c3r8yca7dhxxxxxxxx",
  "RequestId": "1F97FC59-77DF-4D76-BE62-0A13EB4E614C"
}

---------------------------create_vswitch---------------------------
{
  "VSwitchId": "vsw-uf6liy66d9ssuxxxxxxxx",
  "RequestId": "88CCCFED-1448-49D2-8550-71952981A47A"
}

---------------------------create_nat_gateway---------------------------
{
  "NatGatewayId": "ngw-uf6aolgwhssvsxxxxxxxx",
  "BandwidthPackageIds": {
    "BandwidthPackageId": []
  },
  "ForwardTableIds": {
    "ForwardTableId": [
      "ftb-uf6unjiun4i12xxxxxxxx"
    ]
  },
  "RequestId": "62A58351-D608-43A4-849E-1E177E917BEA",
  "SnatTableIds": {
    "SnatTableId": [
      "stb-uf65utljwcdkpxxxxxxxx"
    ]
  }
}

---------------------------allocate_eip_address---------------------------
{
  "EipAddress": "101.xx.xx.110",
  "ResourceGroupId": "rg-acfmxazxxxxxxxx",
  "RequestId": "0565295E-2F49-4511-93BC-747A2D19A6BD",
  "AllocationId": "eip-uf683xrl32ge8xxxxxxxx"
}

---------------------------associate_eip_address eip---------------------------
{
  "RequestId": "8759FCE8-F8C2-4372-91D5-7A25D43FD78C"
}

---------------------------create_forward_entry---------------------------
{
  "ForwardEntryId": "fwd-uf6ng3wt8sfwmxxxxxxxx",
  "RequestId": "CC81BCF6-2F64-40CF-85B0-676A83AC3902"
}

---------------------------describe_eip_address---------------------------
{
  "TotalCount": 1,
  "PageNumber": 1,
  "PageSize": 10,
  "EipAddresses": {
    "EipAddress": [
      {
        "ISP": "BGP",
        "ExpiredTime": "",
        "InternetChargeType": "PayByBandwidth",
        "IpAddress": "101.xx.xx.110",
        "AllocationId": "eip-uf683xrl32ge8xxxxxxxx",
        "PrivateIpAddress": "",
        "Status": "InUse",
        "BandwidthPackageId": "",
        "InstanceId": "ngw-uf6aolgwhssvsxxxxxxxx",
        "InstanceRegionId": "cn-shanghai",
        "RegionId": "cn-shanghai",
        "AvailableRegions": {
          "AvailableRegion": [
            "cn-shanghai"
          ]
        },
        "ResourceGroupId": "rg-acfmxazxxxxxxxx",
        "HasReservationData": false,
        "InstanceType": "Nat",
        "AllocationTime": "2019-04-24T10:56:53Z",
        "Name": "",
        "OperationLocks": {
          "LockReason": []
        },
        "Mode": "NAT",
        "BandwidthPackageType": "",
        "BandwidthPackageBandwidth": "",
        "Bandwidth": "5",
        "HDMonitorStatus": "OFF",
        "ChargeType": "PostPaid",
        "SecondLimited": false,
        "Descritpion": ""
      }
    ]
  },
  "RequestId": "CD2B3613-2A99-4687-9C23-A8E9F1F03048"
}

---------------------------describe_nat_gateway---------------------------
{
  "TotalCount": 1,
  "PageNumber": 1,
  "RequestId": "D7519663-8D3B-4CC5-894F-A6798C89688D",
  "PageSize": 10,
  "NatGateways": {
    "NatGateway": [
      {
        "Status": "Available",
        "BandwidthPackageIds": {
          "BandwidthPackageId": []
        },
        "VpcId": "vpc-uf6c3r8yca7dhxxxxxxxx",
        "Description": "",
        "ForwardTableIds": {
          "ForwardTableId": [
            "ftb-uf6unjiun4i12xxxxxxxx"
          ]
        },
        "IpLists": {
          "IpList": [
            {
              "UsingStatus": "UsedByForwardTable",
              "IpAddress": "101.xx.xx.110",
              "AllocationId": "eip-uf683xrl32ge8xxxxxxxx"
            }
          ]
        },
        "BusinessStatus": "Normal",
        "RegionId": "cn-shanghai",
        "CreationTime": "2019-04-24T10:56:50Z",
        "NatGatewayId": "ngw-uf6aolgwhssvsxxxxxxxx",
        "SnatTableIds": {
          "SnatTableId": [
            "stb-uf65utljwcdkpxxxxxxxx"
          ]
        },
        "AutoPay": false,
        "InstanceChargeType": "PostPaid",
        "ExpiredTime": "",
        "Spec": "Small",
        "Name": ""
      }
    ]
  }
}

---------------------------delete_forward_entry---------------------------
{
  "RequestId": "32C76D08-5738-4B07-A638-ACE5F5F5220E"
}

---------------------------unassociate_eip_address nat--------------------------
-
{
  "RequestId": "AE686920-2CD1-4850-AADC-C249484D4B1A"
}

---------------------------delete_nat_gateway---------------------------
{
  "RequestId": "FEBB1E7A-BA5B-4445-B2AB-5B828C17BBE6"
}

---------------------------release_eip_address---------------------------
{
  "RequestId": "812D5E78-5113-4B92-892D-0B293BAD66F6"
}

---------------------------delete_vswitch---------------------------
{
  "RequestId": "8E13EEE4-21B5-4280-B46B-5C168736DC3A"
}

---------------------------delete_vpc---------------------------
{
  "RequestId": "DCBA91E7-F355-4EB6-83E3-27F2E68A8435"
}