# Automatically mount file shares on an Amazon EC2 Linux instance
You can automatically mount your FSx for Windows File Server file share to access your FSx for Windows File Server file system whenever the Amazon EC2 Linux instance to which it's mounted reboots. To do so, add an entry to the `/etc/fstab` file on the EC2 instance. The `/etc/fstab` file contains information about file systems. The command **mount -a**, which runs during instance startup, mounts the file systems listed in the `/etc/fstab` file.
For an Amazon EC2 Linux instance that is *not* joined to your Active Directory, you can only mount an FSx for Windows File Server file share by using its private IP address. You can get the file system's private IP address using the [Amazon FSx console](https://console.amazonaws.cn/fsx), on the **Network & security** tab, in **Preferred File Server IP Address**.
The following procedure uses Microsoft NTLM authentication. You mount the file system as a user that is a member of the Microsoft Active Directory domain to which the FSx for Windows File Server file system is joined. You can retrieve the credentials for the user account from the `creds.txt` file using the following command.
```
$ cat creds.txt
username=user1
password=Password123
domain=EXAMPLE.COM
```
## To automatically mount a file share on an Amazon Linux EC2 instance not joined to your Active Directory
**To launch and configure the Amazon Linux EC2 instance**
1. Launch an Amazon Linux EC2 instance using the [Amazon EC2 console](https://console.amazonaws.cn/ec2). For more information, see [Launch an instance](https://docs.amazonaws.cn/AWSEC2/latest/UserGuide/EC2_GetStarted.html#ec2-launch-instance) in the *Amazon EC2 User Guide*.
1. Connect to your instance. For more information, see [Connect to your Linux instance](https://docs.amazonaws.cn/AWSEC2/latest/UserGuide/AccessingInstances.html) in the *Amazon EC2 User Guide*.
1. Run the following command to install the `cifs-utils` package. This package is used to mount network file systems like Amazon FSx on Linux.
```
$ sudo yum install cifs-utils
```
1. Create the `/mnt/fsx` directory. This is where you will mount the Amazon FSx file system.
```
$ sudo mkdir /mnt/fsx
```
1. Create the `creds.txt` credentials file in the `/home/ec2-user` directory.
1. Set the file permissions so that only you (the owner) can read the file by running the following command.
```
$ sudo chmod 700 creds.txt
```
**To automatically mount the file system**
1. You automatically mount a file share not joined to your Active Directory by using its private IP address. You can get the file system's private IP address using the [Amazon FSx console](https://console.amazonaws.cn/fsx), on the **Network & security** tab, in **Preferred File Server IP Address**.
1. To automatically mount the file share using its private IP address, add the following line to the `/etc/fstab` file.
```
//{{file-system-IP-address}}/{{file_share}} /mnt/fsx cifs vers={{SMB_version}},sec=ntlmsspi,cred=/home/ec2-user/creds.txt,rsize={{CIFSMaxBufSize}},wsize={{CIFSMaxBufSize}},cache=none 0 0
```
Replace `{{CIFSMaxBufSize}}` with the largest value allowed by your kernel. Run the following command to get this value.
```
$ modinfo cifs | grep CIFSMaxBufSize
parm: CIFSMaxBufSize:Network buffer size (not including header). Default: 16384 Range: 8192 to 130048 (uint)
```
The output shows that the maximum buffer size is 130048.
1. Test the `fstab` entry by using the `mount` command with the 'fake' option in conjunction with the 'all' and 'verbose' options.
```
$ sudo mount -fav
home/ec2-user/fsx : successfully mounted
```
1. To mount the file share, reboot the Amazon EC2 instance.
1. When the instance is available again, verify that the file system is mounted by running the following command.
```
$ sudo mount -l -t cifs
//{{file-system-IP-address}}/{{file_share}} on /mnt/fsx type cifs (rw,relatime,vers={{SMB_version}},sec=ntlmsspi,cache={{cache_code}},username=user1,domain=CORP.EXAMPLE.COM,uid=0,noforceuid,gid=0,noforcegid,addr=192.0.20.0,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,actimeo=1)
```
The line added to the `/etc/fstab` file in this procedure does the following at the given points:
+ `//{{file-system-IP-address}}/{{file_share}}` – Specifies the IP address and share of the Amazon FSx file system you're mounting.
+ `/mnt/fsx` – Specifies the mount point for the Amazon FSx file system on your EC2 instance.
+ `cifs vers={{SMB_version}}` – Specifies the type of file system as CIFS and the SMB protocol version. Amazon FSx for Windows File Server supports SMB versions 2.0 through 3.1.1.
+ `sec=ntlmsspi` – Specifies using NT LAN Manager Security Support Provider Interface to facilitate NTLM challenge-response authentication.
+ `cache={{cache_mode}}` – Sets the cache mode. This option for CIFS cache can impact performance, and you should test which settings work best (and review Linux documentation) for your kernel and workload. Options `strict` and `none` are recommended, because `loose` can cause data inconsistency due to the looser protocol semantics.
+ `cred=/home/ec2-user/creds.txt` – Specifies where to get the user credentials.
+ `_netdev` – Tells the operating system that the file system resides on a device that requires network access. Using this option prevents the instance from mounting the file system until the network service is enabled on the client.
+ `0` – Indicates that the file system should be backed up by `dump`, if it's a nonzero value. For Amazon FSx, this value should be `0`.
+ `0` – Specifies the order in which `fsck` checks file systems at boot. For Amazon FSx file systems, this value should be `0` to indicate that `fsck` shouldn't run at start up.