Controlling network traffic with network policies¶

Workflow¶

The general workflow of using network policies to control inbound network traffic is:

1. Create network rules based on their purpose and type of network identifier.

2. Create one or more network policies that include the network rules that contain the identifiers to be allowed or blocked.

3. Activate the network policy for an account, user, or security integration. A network policy does not restrict network traffic until it is activated.

Interaction between allowed lists and blocked lists¶

When you add a network rule to the allowed list of a network policy, you do not have to use the blocked list to explicitly block other identifiers of the same type; only the allowed identifiers have access. However, identifiers of a different type are not automatically blocked. For example, if you add an IPv4 network rule with a single IP address to the allowed list, all other IPv4 addresses are blocked. There is no need to use the blocked list to restrict access from other IP addresses. However, VPC endpoints still have access unless additional network rules are added to the network policy.

If a network policy has the same IP address values in both the ALLOWED_IP_LIST and the BLOCKED_IP_LIST parameters, Snowflake applies the values in the BLOCKED_IP_LIST parameter first. This behavior also applies to the ALLOWED_NETWORK_RULE_LIST and the BLOCKED_NETWORK_RULE_LIST parameters.

Over private connections, if a network policy has a VPCE ID (AWS) or LinkID (Azure) network rule in the ALLOWED_NETWORK_RULE_LIST parameter, IP network rules in the BLOCKED_NETWORK_RULE_LIST parameter are ignored, causing VPCE ID or LinkID network rules to take precedence.

As an example, a network rule that uses private endpoint identifiers such as Azure LinkIDs or AWS VPCE IDs to restrict access have no effect on requests coming from the public network. If you want to restrict access based on private endpoint identifiers, and then completely block requests from public IPv4 addresses, you must create two separate network rules, one for the allowed list and another for the blocked list.

The following network rules could be combined in a network policy to allow a VPCE ID while blocking public network traffic.

CREATE NETWORK RULE block_public_access
  MODE = INGRESS
  TYPE = IPV4
  VALUE_LIST = ('0.0.0.0/0');

CREATE NETWORK RULE allow_vpceid_access
  MODE = INGRESS
  TYPE = AWSVPCEID
  VALUE_LIST = ('vpce-0fa383eb170331202');

CREATE NETWORK POLICY allow_vpceid_block_public_policy
  ALLOWED_NETWORK_RULE_LIST = ('allow_vpceid_access')
  BLOCKED_NETWORK_RULE_LIST=('block_public_access');

CREATE NETWORK RULE allow_access_rule
  MODE = INGRESS
  TYPE = IPV4
  VALUE_LIST = ('192.168.1.0/24');

CREATE NETWORK RULE block_access_rule
  MODE = INGRESS
  TYPE = IPV4
  VALUE_LIST = ('192.168.1.99');

CREATE NETWORK POLICY public_network_policy
  ALLOWED_NETWORK_RULE_LIST = ('allow_access_rule')
  BLOCKED_NETWORK_RULE_LIST=('block_access_rule');

Network policy precedence¶

You can apply a network policy to an account, a security integration, or a user. If there are network policies applied to more than one of these, the most specific network policy overrides more general network policies. The following summarizes the order of precedence:

Account:

Network policies applied to an account are the most general network policies. They are overridden by network policies applied to a security integration or user.

Security Integration:

Network policies applied to a security integration override network policies applied to the account, but are overridden by a network policy applied to a user.

User:

Network policies applied to a user are the most specific network policies. They override both accounts and security integrations.

Bypassing a network policy¶

It is possible to temporarily bypass a network policy for a set number of minutes by configuring the user object property MINS_TO_BYPASS_NETWORK_POLICY, which can be viewed by executing DESCRIBE USER. Only Snowflake can set the value for this object property. Please contact Snowflake Support to set a value for this property.

Best practices¶

• Limit the scope. Network rules are designed to group together small units of related network identifiers. Previously, network policies often contained a large, monolithic list of IP addresses that should be allowed or blocked. The introduction of network rules changes this strategy. For example, you could break up network identifiers by:

  • Creating a network rule to contain client IP addresses for the North American region, and a different rule for the Europe and Middle Eastern region.

  • Creating a network rule whose purpose is to allow access for a special population, such as highly privileged users and service account users. This network rule can be added to a network policy that is applied to individual users.

  • Creating a network rule that is scoped to one or more data apps.

  With the introduction of network rules, Snowflake recommends that you also limit the scope of network policies. Whenever possible, narrowly scope a network policy to a group of users or a security integration rather than an entire account.

• Add comments. When creating a network rule, use the COMMENT property to keep track of what the rule is supposed to do. Comments are important because Snowflake encourages a large number of small targeted rules over fewer monolithic ones.

  You can use the SHOW NETWORK RULES command to list all of the network rules, including their comments.

Supported identifiers¶

Each network rule contains a list of one or more network identifiers of the same type (e.g. an IPv4 address rule or a private endpoint rule).

A network rule’s TYPE property identifies what type of identifiers the network rule contains.

For a complete list of the types of identifiers that can be restricted using network rules, see Supported network identifiers.

Protecting the Snowflake service¶

This section discusses how to use network rules to restrict access to the Snowflake service only. If you want to restrict access to both the service and the internal stage of an account on AWS, see Protecting internal stages on AWS.

To restrict access to the Snowflake service, set the MODE property of the network rule to INGRESS.

You can then use the TYPE property to specify the identifiers that should be allowed or blocked.

Protecting internal stages on AWS¶

This section discusses how to use network rules to restrict access to internal stages on AWS, including how to simultaneously restrict access to the Snowflake service and internal stage. It includes:

• Limitations

• Prerequisite: Enabling internal stage restrictions

• Guidelines for internal stages

• Strategy for protecting the internal stage only

• Strategies for protecting both service and internal stage

USE ROLE ACCOUNTADMIN;
ALTER ACCOUNT SET ENFORCE_NETWORK_RULES_FOR_INTERNAL_STAGES = true;

Create a network rule¶

You need the CREATE NETWORK RULE privilege on the schema to create a network rule. By default, only the ACCOUNTADMIN and SECURITYADMIN roles, along with the schema owner, have this privilege.

The mode of a network rule that will be used by a network policy must be INGRESS or INTERNAL STAGE.

To gain a better understand of best practices and strategies for creating network rules, see About network rules.

You can create a network rule using Snowsight or by executing a SQL command:

Snowsight:

1. Sign in to Snowsight.

2. Select Admin » Security.

3. Select the Network Rules tab.

4. Select + Network Rule.

5. Enter the name of the network rule.

6. Select the schema of the network rule. Network rule are schema-level objects.

7. Optionally, add a descriptive comment for the network rule to help organize and maintain network rules in the schema.

8. In the Type drop-down, select the type of identifier being defined in the network rule. The Host Port type is not a valid option for network rules being used with network policies.

9. In the Mode drop-down, select Ingress or Internal Stage. The Egress mode is not a valid option for network rules being used with network policies.

10. Enter a comma-separated list of the identifiers that will be allowed or blocked when the network rule is added to a network policy. The identifiers in this list must all be of the type specified in the Type drop-down.

11. Select Create Network Rule.

SQL:

An administrator can execute the CREATE NETWORK RULE command to create a new network rule, specifying a list of network identifiers along with the type of those identifiers.

For example, to use a custom role to create a network rule that can be used to allow or block traffic from a range of IP addresses:

GRANT USAGE ON DATABASE securitydb TO ROLE network_admin;
GRANT USAGE ON SCHEMA securitydb.myrules TO ROLE network_admin;
GRANT CREATE NETWORK RULE ON SCHEMA securitydb.myrules TO ROLE network_admin;
USE ROLE network_admin;

CREATE NETWORK RULE cloud_network TYPE = IPV4 VALUE_LIST = ('47.88.25.32/27');

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Modify a network rule¶

You can modify the network rule using Snowsight or SQL.

Snowsight:

1. Sign in to Snowsight.

2. Select Admin » Security.

3. Select the Network Rules tab.

4. Find the network rule, select the … button, and then select Edit.

5. Modify the network rule as needed.

6. Select Update Network Rule.

SQL:

Execute an ALTER NETWORK RULE statement.

Create a network policy¶

Only security administrators (i.e. users with the SECURITYADMIN role) or higher or a role with the global CREATE NETWORK POLICY privilege can create network policies. Ownership of a network policy can be transferred to another role.

You can create a network policy using Snowsight or SQL:

Snowsight:

1. Sign in to Snowsight.

2. Select Admin » Security.

3. Select the Network Policies tab.

4. Select + Network Policy.

5. Enter the name of the network policy.

6. Optionally, enter a descriptive comment.

7. To add a network rule to the allowed list, select Allowed, and then select Select rule. You can add multiple network rules to the allowed list by re-selecting Select rule.

8. To add a network rule to the blocked list, select Blocked, and then select Select rule. You can add multiple network rules to the blocked list by re-selecting Select rule.

9. Select Create Network Policy.

SQL:

Execute a CREATE NETWORK POLICY statement.

Identify network policies in your account¶

You can identify the network policies in your account using Snowsight or SQL.

Snowsight:

1. Sign in to Snowsight.

2. Select Admin » Security.

3. Select the Network Policies tab.

SQL:

Do one of the following:

• Call the POLICY_REFERENCES Information Schema table function.

• Query the POLICY_REFERENCES or NETWORK_POLICIES Account Usage view.

• Run the SHOW PARAMETERS command as follows:

  SHOW PARAMETERS LIKE 'network_policy' IN ACCOUNT;
  

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Modify a network policy¶

You can add or remove network rules from the allowed list and blocked list of an existing network policy using Snowsight or SQL. If you are editing a network policy that uses the ALLOWED_IP_LIST and BLOCKED_IP_LIST parameters instead of a network rule, you must use SQL to modify the network policy.

Snowsight:

1. Sign in to Snowsight.

2. Select Admin » Security.

3. Select the Network Policies tab.

4. Find the network policy, select the … button, and then select Edit.

5. To add a network rule to the allowed list, select Allowed, and then select Select rule. You can add multiple network rules to the allowed list by re-selecting Select rule.

6. To add a network rule to the blocked list, select Blocked, and then select Select rule. You can add multiple network rules to the blocked list by re-selecting Select rule.

7. To remove a network rule from the allowed list or blocked list of the network policy:

   1. Select Allowed or Blocked.

   2. Find the network rule in the list and select X to remove.

SQL:

Use the ALTER NETWORK POLICY command to add or remove network rules from an existing network policy.

When adding a network rule to the allowed list or blocked list, you can either replace all existing network rules in the list or add the new rule while keeping the existing list. The following examples show each of these options:

• Use the SET clause to replace network rules in the blocked list with a new network rule named other_network:

  ALTER NETWORK POLICY my_policy SET BLOCKED_NETWORK_RULE_LIST = ( 'other_network' );
  

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• Use the ADD clause to add a single network rule to the allowed list of an existing network policy. Network rules that were previously added to the policy’s allowed list remain in effect.

  ALTER NETWORK POLICY my_policy ADD ALLOWED_NETWORK_RULE_LIST = ( 'new_rule' );
  

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You can also remove a network rule from an existing list without replacing the entire list. For example, to remove a network rule from the network policy’s blocked list:

ALTER NETWORK POLICY my_policy REMOVE BLOCKED_NETWORK_RULE_LIST = ( 'other_network' );

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Activate a network policy for your account¶

Activating a network policy for an account enforces the policy for all users in the account.

Only security administrators (i.e. users with the SECURITYADMIN role) or higher or a role with the global ATTACH POLICY privilege can activate a network policy for an account.

Once the policy is associated with your account, Snowflake restricts access to your account based on the allowed list and blocked list. Any user who attempts to log in from an network origin restricted by the rules is denied access. In addition, when a network policy is associated with your account, any restricted users who are already logged into Snowflake are prevented from executing further queries.

You can create multiple network policies, however only one network policy can be associated with an account at any one time. Associating a network policy with your account automatically removes the currently-associated network policy (if any).

Note that your current IP address or private endpoint identifier must be included in the allowed list in the policy. Otherwise, when you activate the policy, Snowflake returns an error. In addition, your current identifier cannot be included in the blocked list.

If you want to determine whether there is already an account-level network policy before activating a new one, see Identify an activated network policy.

You can activate a network policy for your account using Snowsight or SQL:

Snowsight:

1. Select Admin » Security.

2. Select the Network Policies tab.

3. Find the network policy, select the … button, and then select Activate.

4. Select Activate policy.

SQL:

Execute the ALTER ACCOUNT statement to set the NETWORK_POLICY parameter for the account. For example:

ALTER ACCOUNT SET NETWORK_POLICY = my_policy;

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Activate network policies for individual users¶

To enforce a network policy for a specific user in your Snowflake account, activate the network policy for the user. Only a single network policy can be activated for each user at a time. The ability to activate different network policies for different users allows for granular control. Associating a network policy with a user automatically removes the currently-associated network policy (if any).

Once the policy is associated with the user, Snowflake restricts access to the user based on the allowed list and blocked list. If the user with an activated user-level network policy attempts to log in from a network location restricted by the rules, the user is denied access to Snowflake.

In addition, when a user-level network policy is associated with the user and the user is already logged into Snowflake, if the user’s network location does not match the user-level network policy rules, Snowflake prevents the user from executing further queries.

If you want to determine whether there is already a user-level network policy before activating a new one, see Identify an activated network policy.

To activate a network policy for an individual user, execute the ALTER USER command to set the NETWORK_POLICY parameter for the user. For example, execute:

ALTER USER joe SET NETWORK_POLICY = my_policy;

Activate network policies for security integrations¶

Some security integrations support activating a network policy to control network traffic that is governed by that integration. These security integrations have a NETWORK_POLICY parameter that activates the network policy for the integration. Currently, SCIM and Snowflake OAuth support integration-level network policies.

For example, you could activate a network policy when creating a new Snowflake OAuth security integration. The network policy would restrict the access of requests trying to authenticate.

CREATE SECURITY INTEGRATION oauth_kp_int
  TYPE = oauth
  ENABLED = true
  OAUTH_CLIENT = custom
  OAUTH_CLIENT_TYPE = 'CONFIDENTIAL'
  OAUTH_REDIRECT_URI = 'https://example.com'
  NETWORK_POLICY = mypolicy;

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You can execute the ALTER SECURITY INTEGRATION … SET NETWORK_POLICY statement to activate a network policy for an existing security integration.

Identify an activated network policy¶

You can identify which network policy is activated at the account, user, or integration level.

Account:

1. Select Admin » Security.

2. Select the Network Policies tab.

3. Sort the Status column to view the network policies.

   The Status column shows active and inactive network policies. Select the column value to view more details about the network policy, edit the policy, and delete the network policy. You can activate and deactivate a network policy that is set on your account.

Alternatively, you can call the POLICY_REFERENCES function and specify a network policy. The values in the ref_entity_name and ref_entity_domain columns for an individual row indicate the object on which the network policy is set.

Creating a network policy with Classic Console¶

Only security administrators (i.e. users with the SECURITYADMIN role) or higher or a role with the global CREATE NETWORK POLICY privilege can create network policies. Ownership of a network policy can be transferred to another role.

1. Click Account » Policies. The Policies page appears.

2. Click the Create button. The Create Network Policy dialog appears.

3. In the Name field, enter a name for the network policy.

4. In the Allowed IP Addresses field, enter one or more IPv4 addresses that are allowed access to this Snowflake account, separated by commas.

   Note

   To block all IP addresses except for a set of specific addresses, you only need to define an allowed IP address list. Snowflake automatically blocks all IP addresses not included in the allowed list.

5. In the Blocked IP Addresses field, optionally enter one or more IPv4 addresses that are denied access to this Snowflake account, separated by commas. Note that this field is not required and is used primarily to deny specific addresses in a range of addresses in the allowed list.

6. Enter other information for the network policy, as needed, and click Finish.

Modifying a network policy with Classic Console¶

If you are using the Classic Console, do the following to modify a network policy:

1. Click Account » Policies.

2. Click on a policy to select it and populate the side panel on the right.

3. Click the Edit button in the right panel.

4. Modify the fields as necessary:

   • To remove an IP address from the Allowed IP Addresses or Blocked IP Addresses list, click the x next to the entry.

   • To add an IP address to either list, enter one or more comma-separated IPv4 addresses in the appropriate field, and click the Add button.

5. Click Save.

Activating a network policy with Classic Console¶

If you are using the Classic Console, you can enforce a network policy for all users in your Snowflake account by activating the network policy for your account.

1. Click Account » Policies.

2. Click on a policy to select it and populate the side panel on the right.

3. Click the Activate button in the right panel.