# Mounting EFS file systems using the EFS mount helper After you install the Amazon EFS client (`amazon-efs-utils`), you can use the EFS mount helper to mount EFS file systems on your EC2 Linux and Mac instances running a [supported distributions](using-amazon-efs-utils.md#efs-utils-supported-distros). Amazon EFS does not support mounting from EC2 Windows instances. **Important** We recommend that you always use the most current version of `amazon-efs-utils` to ensure successful mounting. For example, versions of `amazon-efs-utils` prior to 2.3 do not support mounting with IPv6 addresses. When mounting a file system, the mount helper defines a new network file system type, called `efs`, which is fully compatible with the standard `mount` command in Linux. The mount helper also supports mounting an EFS file system at instance boot time automatically by using entries in the `/etc/fstab` configuration file on EC2 Linux instances. **Warning** Use the `_netdev` option, used to identify network file systems, when mounting your file system automatically. If `_netdev` is missing, your EC2 instance might stop responding. This result is because network file systems need to be initialized after the compute instance starts its networking. For more information, see [Automatic mounting fails and the instance is unresponsive](troubleshooting-efs-mounting.md#automount-fails). You can mount a file system by specifying one of the following properties: + **File system DNS name** – If you use the file system DNS name, and the mount helper cannot resolve it, for example when you are mounting a file system in a different VPC, it will fall back to using the mount target IP address. For more information, see [Mounting EFS file systems from another Amazon Web Services account or VPC](manage-fs-access-vpc-peering.md). + **File system ID** – If you use the file system ID, the mount helper resolves it to the local IP address of the mount target elastic network interface (ENI) without calling external resources. + **Mount target IP address** – You can use the IP address of one of the file systems mount targets. You can find the value for all of these properties in the Amazon EFS console. The file system DNS name is found in the **Attach** screen. When encryption of data in transit is declared as a mount option for your EFS file system, the mount helper initializes a client `stunnel` process, and a supervisor process called `amazon-efs-mount-watchdog`. The `amazon-efs-mount-watchdog` process monitors the health of TLS mounts, and is started automatically the first time an EFS file system is mounted over TLS. If your client is running on Linux, this process is managed by either `upstart` or `systemd` depending on your Linux distribution. For clients running on a supported macOS, it is managed by `launchd`. `Stunnel` is an open-source multipurpose network relay. The client `stunnel` process listens on a local port for inbound traffic, and the mount helper redirects NFS client traffic to this local port. The mount helper uses TLS version 1.2 to communicate with your file system. Using TLS requires certificates, and these certificates are signed by a trusted Amazon Certificate Authority. For more information on how encryption works, see [Data encryption in Amazon EFS](encryption.md). **Topics** + [Mount settings used by EFS mount helper](mount-helper-setting.md) + [Getting support logs](mount-helper-logs.md) + [Prerequisites for using the EFS mount helper](mount-helper-prerequisites.md) + [Mounting on EC2 Linux instances using the EFS mount helper](mounting-fs-mount-helper-ec2-linux.md) + [Mounting on EC2 Mac instances using the EFS mount helper](mounting-fs-mount-helper-ec2-mac.md) + [Mounting EFS file systems from a different Amazon Web Services Region](mount-different-region.md) + [Mounting One Zone file systems](mounting-one-zone.md) + [Mounting with IAM authorization](mounting-IAM-option.md) + [Mounting with EFS access points](mounting-access-points.md) + [Mounting EFS to multiple EC2 instances](mount-multiple-ec2-instances.md) + [Mounting EFS file systems from another Amazon Web Services account or VPC](manage-fs-access-vpc-peering.md)