About NFSv4.1 protocol

The following guide describes the NFSv4.1 protocol.

Filestore offers NFSv4.1 protocol support for instances created in the following service tiers:

Zonal
Regional
Enterprise

This capability can be integrated with Managed Service for Microsoft Active Directory (Managed Microsoft AD) to support workloads that require client and server authentication, message data integrity checks, and in-transit data encryption, capabilities previously unavailable in Filestore.

Authentication is supported using LDAP and Kerberos and includes the following security flavors (settings):

Client and server authentication (krb5).
Message integrity checks (krb5i). Includes the capabilities of the previous setting.
In-transit data encryption (krb5p). Includes the capabilities of the previous setting.

Managed Microsoft AD is the only fully-managed Google Cloud solution that supports both LDAP and Kerberos, requirements for the NFSv4.1 protocol and its security and privacy benefits. While integration with Managed Microsoft AD is not required, it is highly recommended for an optimal Google Cloud user experience to manage user accounts and fluctuating groups and permissions.

Should you use NFSv4.1?

Many enterprise organizations rely on legacy systems for business-critical operations. Many of these systems require authentication and in-transit encryption for their network file storage. NFSv3 was not designed with authentication in mind. Filestore's NFSv4.1 protocol integration with Managed Microsoft AD now meets this critical user requirement.

For more information on NFSv4.1 benefits, see About supported protocols.

Understanding network-based access control lists (ACLs) in NFSv4.1.

In NFSv3, only the sys security flavor is supported. This setting trusts the user uid and gid provided by the client during mounting.

In the Filestore NFSv4.1 protocol, several network ACL security flavors or settings are available:

krb5

Authenticates the client using a Kerberos ticket, which is validated against the Managed Microsoft AD Kerberos server.
krb5i

Includes the authentication provided by krb5 and also uses Kerberos to run message integrity checks on all network traffic to and from the instance.
krb5p

Includes the authentication provided by krb5 and message integrity checks of krb5i and also uses Kerberos for in-transit data encryption.

If you want to take advantage of these options, Managed Service for Microsoft Active Directory integration is required. For more information, see Create a Filestore instance with Managed Microsoft AD.

If a Managed Service for Microsoft Active Directory domain isn't specified, only the sys security flavor is supported.

For more information, see NFSv4.1 limitations.

Mounting Filestore NFSv4.1 instances on Linux clients

The following steps show you how to mount instances on Linux clients.

Mount with sec=sys for standard NFS permissions:

sudo mount -vvvv -t nfs4 -o vers=4.1,sec=sys,rw \ FILESTORE-INSTANCE-FQDN:/INSTANCE_SHARE_POINT /MOUNT_POINT

Mount with sec=krb5 for Kerberos-based authentication:

sudo mount -vvvv -t nfs4 -o vers=4.1,sec=krb5,rw \ FILESTORE-INSTANCE-FQDN:/INSTANCE_SHARE_POINT /MOUNT_POINT

Mount with sec=krb5i for Kerberos-based authentication and message integrity checks:

sudo mount -vvvv -t nfs4 -o vers=4.1,sec=krb5i,rw \ FILESTORE-INSTANCE-FQDN:/INSTANCE_SHARE_POINT /MOUNT_POINT

Mount with sec=krb5p for Kerberos-based authentication, integrity checks, and in-transit encryption:
```
sudo mount -vvvv -t nfs4 -o vers=4.1,sec=krb5p,rw \ FILESTORE-INSTANCE-FQ
DN:/INSTANCE_SHARE_POINT /MOUNT_POINT
```
Replace the following:
- FILESTORE-INSTANCE-FQDN is the fully-qualified domain name where the Filestore instance is located.
- INSTANCE_SHARE_POINT is the file share name of the Filestore instance that you want to connect.
- MOUNT_POINT is the mount point or directory name where you want to mount.

Linux client configuration

An NFSv4.1 Filestore instance allows clients to perform NFS operations using various security flavors. These flavors are configured by the instance administrator through network ACLs on the Filestore NFSv4.1 instance, during creation or if updated after creation.

The sys security flavor uses standard Unix authentication, while krb5, krb5i, and krb5p flavors use Kerberos-based authentication.

The krb5, krb5i, and krb5p flavors require the clients to be connected to the same Managed Microsoft AD domain as the Filestore instance. Complete the following steps appropriate for your environment.

Ubuntu image

SSH to the Compute Engine instance.
Run the following commands to join the Managed Microsoft AD domain.
1. Run the following setup command:
```
sudo apt-get update \
sudo apt-get -y -qq install adcli realmd sssd sssd-tools packagekit krb5-user \ nfs-common expect retry
```
2. When prompted for realm, replace the existing entry with the Managed Microsoft AD domain used on the Filestore instance. Enter the value in uppercase, then press the arrow key to select OK, then press Enter.
3. When prompted for hosts, leave it empty and proceed.
4. Complete either of the following steps:
  - For VMs with a hostname length that is less than or equal to 15 characters, run the following command:
```
sudo realm join -vU JOIN_DOMAIN_USER --automatic-id-mapping=no MANAGED_AD_DOMAIN_NAME
```
    Replace the following:
    - JOIN_DOMAIN_USER is the name of the user account used to join the domain.
    - MANAGED_AD_DOMAIN_NAME is the domain name of the Managed Microsoft AD service you want to use.
  - For VMs with a hostname length that is greater than 15 characters, run the following command:
```
sudo realm join -vU JOIN_DOMAIN_USER --automatic-id-mapping=no \ --user-principal=host/`hostname -f`@MANAGED_AD_REALM_NAME MANAGED_AD_DOMAIN_NAME
```
    Replace the following:
    - JOIN_DOMAIN_USER is the name of the user account used to join the domain.
    - MANAGED_AD_REALM_NAME is the realm name of the Managed Microsoft AD service you want to use.
    - MANAGED_AD_DOMAIN_NAME is the domain name of the Managed Microsoft AD service you want to use.

Update Kerberos configuration. Update /etc/krb5.conf with the required realm definition and realm-domain mapping:

 [realms]
          DOMAIN_NAME = {
                   kdc = DOMAIN_NAME
                   default_domain = DOMAIN_NAME
          }
 [domain_realm]
          .domain_name_lowercase = DOMAIN_NAME
          domain_name_lowercase = DOMAIN_NAME

Replace the following:

DOMAIN_NAME is the domain name you want to use, entered in uppercase.
domain_name_lowercase is the domain name you want to use, entered in lowercase.

Refer to the following for an example:

[realms]
       FILE.DEMO.LOCAL = {
                kdc = FILE.DEMO.LOCAL
                default_domain = FILE.DEMO.LOCAL
       }

[domain_realm]
       .file.demo.local = FILE.DEMO.LOCAL
       file.demo.local = FILE.DEMO.LOCAL

Run the rpc-gssd service. Add the following No-Strip attribute value to [General] section inside /etc/idmapd.conf:
```
 [General]
 No-Strip = both
```
Run the following command:
```
sudo systemctl restart rpc-gssd
```

Centos image

Ssh to the Compute Engine instance.

Join the Managed Microsoft AD domain:

sudo yum update \
sudo yum install -y adcli realmd sssd samba-common-tools krb5-workstation nfs-utils \ bind-utils openldap-clients

Complete either of the following steps:
- For VMs with a hostname length less than or equal to 15 characters, run the following command:
```
sudo realm join -vU JOIN_DOMAIN_USER --automatic-id-mapping=no MANAGED_AD_DOMAIN_NAME
```
  Replace the following:
  - JOIN_DOMAIN_USER is the name of the user account used to join the domain.
  - MANAGED_AD_DOMAIN_NAME is the domain name of the Managed Microsoft AD service you want to use.
- For VMs with a hostname length greater than 15 characters, run the following command:
```
sudo realm join -vU JOIN_DOMAIN_USER --automatic-id-mapping=no \ --user-principal=host/`hostname -f`@MANAGED_AD_REALM_NAME MANAGED_AD_DOMAIN_NAME
```
  Replace the following:
  - JOIN_DOMAIN_USER is the name of the user account used to join the domain.
  - MANAGED_AD_REALM_NAME is the realm name of the Managed Microsoft AD service you want to use.
  - MANAGED_AD_DOMAIN_NAME is the domain name of the Managed Microsoft AD service you want to use.
Ensure that sssd service is running:
```
sudo systemctl status sssd
```
Run rpc-gssd service. Add the following below the No-Strip attribute value to the [General] section inside /etc/idmapd.conf:
```
[General]
No-Strip = both
```
Run the following command. This command helps ensure the NFS client won't strip the domain name from the NFS server hostname. For more information, see NFS Ganesha List Archives and Arch Linux Archive:
```
sudo systemctl start rpc-gssd
```

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