# Configuring VPCs

VPC provisions an isolated virtual network environment defined and managed by yourself, improving the security of cloud resources and simplifying network deployment. When using SFS, a file system and the associated ECSs need to belong to the same VPC for file sharing.

In addition, VPC can use network access control lists (ACLs) to implement access control. A network ACL is an access control policy system for one or more subnets. Based on inbound and outbound rules, it determines whether data packets are allowed in or out of any associated subnet. In the VPC list of a file system, each time an authorization address is added and the corresponding permissions are set, a network ACL is created.

For more information about VPC, see the Virtual Private Cloud User Guide.

#### Scenarios

Multiple VPCs can be configured for an SFS Capacity-Oriented file system so that ECSs belonging to different VPCs can share the same file system, as long as the VPCs that the ECSs belong to are added to the VPC list of the file system or the ECSs are added to the authorized addresses of the VPCs.

This section describes how to configure multi-VPC access for an SFS Capacity-Oriented file system.

#### Restrictions

- You can add a maximum of 20 VPCs for each file system. A maximum of 400 ACL rules for added VPCs can be created. When adding a VPC, the default IP address 0.0.0.0/0 is automatically added.
- If a VPC bound to the file system has been deleted from the VPC console, the IP address/address segment of this VPC in the VPC list of the file system can still be seen as activated. However, this VPC cannot be used any longer and you are advised to delete the VPC from the list.

#### Procedure

1. Log in to SFS Console.
2. In the file system list, click the name of the target file system. On the page that is displayed, locate the Authorizations area.
3. If no VPCs are available, apply for one. You can add multiple VPCs for a file system. Click Add Authorized VPC and the Add Authorized VPC dialog box is displayed. See Figure 1.

   You can select multiple VPCs from the drop-down list.

   Figure 1 Adding VPCs
4. Click OK. A successfully added VPC is displayed in the list. When adding a VPC, the default IP address 0.0.0.0/0 is automatically added. The default read/write permission is Read-write, the default user permission is no_all_squash, and the default root permission is no_root_squash.
5. View the VPC information in the VPC list. For details about the parameters, see Table 1.

   Table 1 Parameter description
   Parameter | Description
   --- | ---
   Name | Name of the added VPC, for example, vpc-01
   Authorized Addresses/Segments | Number of added IP addresses or IP address segments
   Operation | The value can be Add or Delete. Add: Adds an authorized VPC. This operation configures the IP address, read/write permission, user permission, user root permission, and priority. For details, see Table 2. Delete: Deletes this VPC.

6. Click on the left of the VPC name to view details about the IP addresses/segments added to this VPC. You can add, edit, or delete IP addresses/segments. In the Operation column of the target VPC, click Add. The Add Authorized Address/Segment dialog box is displayed. See Figure 2. Table 2 describes the parameters to be configured.

   Figure 2 Adding an authorized address or segment

   Table 2 Parameter description
   Parameter | Description
   --- | ---

   Authorized Address/Segment

   - Only one IPv4 address or address segment can be entered.
   - The entered IPv4 address or address segment must be valid and cannot be an IP address or address segment starting with 0 except 0.0.0.0/0. The value 0.0.0.0/0 indicates any IP address in the VPC. In addition, the IP address or address segment cannot start with 127 or any number from 224 to 255, such as 127.0.0.1, 224.0.0.1, or 255.255.255.255. This is because IP addresses or address segments starting with any number from 224 to 239 are class D addresses and they are reserved for multicast. IP addresses or address segments starting with any number from 240 to 255 are class E addresses and they are reserved for research purposes. If an invalid IP address or address segment is used, the access rule may fail to be added or the added access rule cannot take effect.
   - Multiple addresses separated by commas (,), such as 10.0.1.32,10.5.5.10 are not allowed.
   - An address segment, for example, 192.168.1.0 to 192.168.1.255, needs to be in the mask format like 192.168.1.0/24. Other formats such as 192.168.1.0-255 are not allowed. The number of bits in a subnet mask must be an integer ranging from 0 to 31. The number of bits 0 is valid only in 0.0.0.0/0.

   Read-Write Permission | The value can be Read-write or Read-only. The default value is Read-write.

   User Permission

   Specifies whether to retain the user identifier (UID) and group identifier (GID) of the shared directory. The default value is no_all_squash.
   - all_squash: The UID and GID of a shared directory are mapped to user nobody, which is applicable to public directories.
   - no_all_squash: The UID and GID of a shared directory are retained.

   User Root Permission

   Specifies whether to allow the root permission of the client. The default value is no_root_squash.
   - root_squash: Clients cannot access as the root user. When a client accesses as the root user, the user is mapped to the nobody user.
   - no_root_squash: Clients are allowed to access as the root user who has full control and access permissions of the root directories.

   Priority

   The value must be an integer ranging from 0 to 100. 0 indicates the highest priority, and 100 indicates the lowest priority. In the same VPC, the permission of the IP address or address segment with the highest priority is preferentially used. If some IP addresses or address segments are of the same priority, the permission of the most recently added or modified one is used.

   For example, if the IP address for mounting is 10.1.1.32 and both 10.1.1.32 (read/write) with priority 100 and 10.1.1.0/24 (read-only) with priority 50 meet the requirements, the permission of 10.1.1.0/24 (read-only) with priority 50 is used. That is, if there is no other authorized priority, the permission of all IP addresses in the 10.1.1.0/24 segment, including 10.1.1.32, is read-only.

   For an ECS in VPC A, its IP address can be added to the authorized IP address list of VPC B, but the file system of VPC B cannot be mounted to this ECS. The VPC used by the ECS and the file system must be the same.

#### Verification

After another VPC is configured for the file system, if the file system can be mounted to ECSs in the VPC and the ECSs can access the file system, the configuration is successful.

#### Example

A user creates an SFS Capacity-Oriented file system A in VPC-B. The network segment is 10.0.0.0/16. The user has an ECS D in VPC-C, using the private IP address 192.168.10.11 in network segment 192.168.10.0/24. If the user wants to mount file system A to ECS D and allow the file system to be read and written, the user needs to add VPC-C to file system A's VPC list, add ECS D's private IP address or address segment to the authorized addresses of VPC-C, and then set Read-Write Permission to Read-write.

The user purchases an ECS F that uses the private IP address 192.168.10.22 in the VPC-C network segment 192.168.10.0/24. If the user wants ECS F to have only the read permission for file system A and its read priority to be lower than that of ECS D, the user needs to add ECS F's private IP address to VPC-C's authorized addresses, set Read-Write Permission to Read-only, and set Priority to an integer between 0 and 100 and greater than the priority set for ECS D.

Parent topic: Network Configuration