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Configure connections with network attachments
BigQuery supports federated queries that let you send a query statement to external databases and get the result back as a temporary table. Federated queries use the BigQuery Connection API to establish a connection. This document shows you how to increase the security of this connection.
Because the connection connects directly to your database, you must allow traffic from Google Cloud to your database engine. To increase security, you should only allow traffic that comes from your BigQuery queries. This traffic restriction can be accomplished in one of two ways:
By defining a static IP address that is used by a BigQuery connection and adding it to the firewall rules of the external data source.
By creating a VPN between BigQuery and your internal infrastructure, and using it for your queries.
Both of these techniques are supported through the use of network attachments.
Before you begin
Grant Identity and Access Management (IAM) roles that give users the necessary permissions to perform each task in this document.
Required roles
To get the permissions that you need to configure a connection with network attachments, ask your administrator to grant you the Compute Admin (roles/compute.admin) IAM role on the project. For more information about granting roles, see Manage access to projects, folders, and organizations.
This predefined role contains the permissions required to configure a connection with network attachments. To see the exact permissions that are required, expand the Required permissions section:
Required permissions
The following permissions are required to configure a connection with network attachments:
For standard regions, network attachments must be located in the same region as the connection. For connections in the US multi-region, the network attachment must be located in the us-central1 region. For connections in the EU multi-region, the network attachment must be located in the europe-west4 region.
You can't make any changes to your network attachment after you create it. To configure anything in a new way, you need to recreate the network attachment.
Network attachments can't be deleted unless the producer (BigQuery) deletes the allocated resources. To initiate the deletion process, you must contact BigQuery support.
Create a network attachment
When you create a connection for query federation, you can use the optional network attachment parameter, which points to a network attachment that provides connectivity to the network from which the connection to your database is established. You can create a network attachment by either defining a static IP address or creating a VPN. For either option, do the following:
Optional: Depending on your organization's security policies, you might need to configure your Google Cloud firewall to allow egress by creating a firewall rule with the following settings:
Set Targets to All instances in the network.
Set Destination IPv4 ranges to the entire IP address range.
Set Specified protocols and ports to the port that is used by your database.
Configure your internal firewall to allow ingress from the static IP address that you created. This process varies by data source.
Create a connection, and include the name of the network attachment that you created.
Run any federated query to synchronize your project with the network attachment.
Your connection is now configured with a network attachment, and you can run federated queries.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-25 UTC."],[[["\u003cp\u003eBigQuery federated queries can connect to external databases, using the BigQuery Connection API to establish this connection.\u003c/p\u003e\n"],["\u003cp\u003eTo enhance connection security, traffic should be restricted to only originate from BigQuery queries, achieved by using either a static IP address or a VPN.\u003c/p\u003e\n"],["\u003cp\u003eNetwork attachments, which can be created with a static IP address or a VPN, are used to define this connectivity to external data sources and are compatible with SAP Datasphere connections.\u003c/p\u003e\n"],["\u003cp\u003eTo configure the connection, after creating a VPC network and subnet, you must also create a network attachment using either a Cloud NAT gateway with a static IP address or a VPN.\u003c/p\u003e\n"],["\u003cp\u003eAfter creating the network attachment, a connection is created which will include the name of this attachment, allowing the project to synchronize using a federated query.\u003c/p\u003e\n"]]],[],null,["# Configure connections with network attachments\n==============================================\n\nBigQuery supports federated queries that let you send a query\nstatement to external databases and get the result back as a temporary table.\nFederated queries use the BigQuery Connection API to establish a connection. This\ndocument shows you how to increase the security of this connection.\n\nBecause the connection connects directly to your database, you must allow\ntraffic from Google Cloud to your database engine. To increase security, you\nshould only allow traffic that comes from your BigQuery queries.\nThis traffic restriction can be accomplished in one of two ways:\n\n- By defining a static IP address that is used by a BigQuery connection and adding it to the firewall rules of the external data source.\n- By creating a VPN between BigQuery and your internal infrastructure, and using it for your queries.\n\nBoth of these techniques are supported through the use of\n[network attachments](/vpc/docs/create-manage-network-attachments).\n\nBefore you begin\n----------------\n\nGrant Identity and Access Management (IAM) roles that give users the necessary permissions\nto perform each task in this document.\n\n### Required roles\n\n\nTo get the permissions that\nyou need to configure a connection with network attachments,\n\nask your administrator to grant you the\n\n\n[Compute Admin](/iam/docs/roles-permissions/compute#compute.admin) (`roles/compute.admin`)\nIAM role on the project.\n\n\nFor more information about granting roles, see [Manage access to projects, folders, and organizations](/iam/docs/granting-changing-revoking-access).\n\n\nThis predefined role contains\n\nthe permissions required to configure a connection with network attachments. To see the exact permissions that are\nrequired, expand the **Required permissions** section:\n\n\n#### Required permissions\n\nThe following permissions are required to configure a connection with network attachments:\n\n- ` compute.networkAttachments.get `\n- ` compute.networkAttachments.update`\n\n\nYou might also be able to get\nthese permissions\nwith [custom roles](/iam/docs/creating-custom-roles) or\nother [predefined roles](/iam/docs/roles-overview#predefined).\n\nFor more information about IAM roles and permissions in\nBigQuery, see\n[BigQuery IAM roles and permissions](/bigquery/docs/access-control).\n\nLimitations\n-----------\n\nConnections with network attachments are subject to the following limitations:\n\n- Network attachments are supported only for [SAP Datasphere connections](/bigquery/docs/sap-datasphere-federated-queries).\n- For standard regions, network attachments must be located in the same region as the connection. For connections in the `US` multi-region, the network attachment must be located in the `us-central1` region. For connections in the `EU` multi-region, the network attachment must be located in the `europe-west4` region.\n- You can't make any changes to your network attachment after you create it. To configure anything in a new way, you need to recreate the network attachment.\n- Network attachments can't be deleted unless the producer (BigQuery) deletes the allocated resources. To initiate the deletion process, you must [contact BigQuery support](/bigquery/docs/support).\n\nCreate a network attachment\n---------------------------\n\nWhen you create a connection for query federation, you can use the optional\nnetwork attachment parameter, which points to a network attachment that provides\nconnectivity to the network from which the connection to your database is\nestablished. You can create a network attachment by either defining a static IP\naddress or creating a VPN. For either option, do the following:\n\n1. If you don't already have one,\n [create a VPC network and subnet](/vpc/docs/create-modify-vpc-networks#create-custom-network).\n\n2. If you want to create a network attachment by defining a static IP address,\n [create a Cloud NAT gateway with a static IP address](/nat/docs/set-up-manage-network-address-translation#create-nat-gateway),\n using the network, region, and subnet that you created. If you want to\n create a network attachment by creating a VPN, create a\n [VPN that is connected to your private network](/network-connectivity/docs/vpn).\n\n3. [Create a network attachment](/vpc/docs/create-manage-network-attachments#create-manual-accept)\n using the network, region, and subnet that you created.\n\n4. Optional: Depending on your organization's security policies, you might need\n to configure your Google Cloud firewall to allow egress by\n [creating a firewall rule](/firewall/docs/using-firewalls#creating_firewall_rules)\n with the following settings:\n\n - Set **Targets** to **All instances in the network**.\n - Set **Destination IPv4 ranges** to the entire IP address range.\n - Set **Specified protocols and ports** to the port that is used by your database.\n5. Configure your internal firewall to allow ingress from the static IP address\n that you created. This process varies by data source.\n\n6. [Create a connection](/bigquery/docs/connections-api-intro), and include the\n name of the network attachment that you created.\n\n7. Run any [federated query](/bigquery/docs/federated-queries-intro) to\n synchronize your project with the network attachment.\n\nYour connection is now configured with a network attachment, and you can run\nfederated queries.\n\nPricing\n-------\n\n- Standard [federated query pricing](/bigquery/docs/federated-queries-intro#pricing) applies.\n- Using VPC is subject to [Virtual Private Cloud pricing](/vpc/pricing).\n- Using Cloud VPN is subject to [Cloud VPN pricing](/network-connectivity/docs/vpn/pricing).\n- Using Cloud NAT is subject to [Cloud NAT pricing](/nat/pricing).\n\nWhat's next\n-----------\n\n- Learn about different [connection types](/bigquery/docs/connections-api-intro).\n- Learn about [managing connections](/bigquery/docs/working-with-connections).\n- Learn about [federated queries](/bigquery/docs/federated-queries-intro)."]]
