Mounting Network File Systems

Using sshfs File Shares in Linux

Note

This guide describes connecting to either local or remote server file systems from Linux or Unix desktops. The specific commands in this guide are given for Ubuntu; syntax will differ with other systems.

Part 1: Configure File Systems

This section must be performed once on each local desktop to prepare the system to connect. First configure the desktop to use remote filesystems by installing packages and loading the kernel module fuse. (The fuse file system is not included in default system configurations.) For Debian/Ubuntu users, use your preferred editor to create a script file on the Desktop as follows (cut and paste the text):

#!/usr/bin/env bash
apt-get --no-upgrade install sshfs fuse-utils autofs
modprobe --first-time fuse
if [ $? -eq 0 ]
then echo "fuse" >> /etc/modules
fi

Save the bash script on the Desktop as fuse.sh. Open a terminal session on the desktop, set the permissions for the file to executable, and execute the script:

chmod +x fuse.sh
sudo ./fuse.sh

Part 2. Setup Server Access

This section is performed once for each remote server, to add information about the server to the local desktop. Instructions are provided using Domain Names. IP addresses would also work, but then the shares would not be accessible both locally and remotely. When DNS is properly configured, access works whether the connection is local, bridged, VPN, or public.

Note

Throughout these instructions, replace HOSTSERVER, DOMAIN, and TLD with the name of the server to be accessed, the domain for the server, and the top-level domain (.com, .net, etc.). For example, HOSTSERVER.DOMAIN.TLD might be replaced with officeserver.aaltsys.com for the office server at AAltSys.

/etc/auto.master

Each entry in auto.master defines a file access point which binds to a remote server. For example, file requests to /mnt/HOSTSERVER will automount HOSTSERVER shares. Shares will be unmounted if idle for over 30 seconds.

/etc/auto.HOSTSERVER

A list of share mappings is required for each remote server. Here HOSTSERVER has two shares, PUBLIC and *. Entries start with a name (e.g., public), followed by configuration parameters: -fstype=fuse,rw,..., and user ssh credentials: IdentityFile=$HOME/.ssh/id_rsa. Last is the URI for accessing the share: :sshfs\#$USER@HOSTSERVER.DOMAIN.TLD\:/.../public.

Assign a mount point (a file directory pointer) for the remote server to use:

sudo mkdir /mnt/HOSTSERVER/

The master configuration file, auto.master, provides autofs with mount names and server configurations for shares. At the terminal, type the command:

sudoedit /etc/auto.master

and add the following line of text, replacing HOSTSERVER with the server name:

/mnt/HOSTSERVER /etc/auto.HOSTSERVER --timeout=30,--ghost

Now create and edit the server configuration file, auto.HOSTSERVER, to provide server-specific information:

sudoedit /etc/auto.HOSTSERVER

and enter and save the share configuration information, such as:

public -fstype=fuse,rw,nodev,nonempty,noatime,max_read=65536,allow_other,compression=yes,uid=$UID,gid=$GID,StrictHostKeyChecking=no,IdentityFile=$HOME/.ssh/id_rsa,umask=0007 :sshfs\#$USER@HOSTSERVER.DOMAIN.TLD\:/home/samba/shares/public/
* -fstype=fuse,rw,allow_other,nodev,nonempty,noatime,max_read=65536,compression=yes,uid=$UID,gid=$GID,StrictHostKeyChecking=no,IdentityFile=$HOME/.ssh/id_rsa,umask=0077 :sshfs\#$USER@HOSTSERVER.DOMAIN.TLD\:/home/&

Restart the autofs module to load the changed configuration:

sudo /etc/init.d/autofs restart
sudo ssh HOSTSERVER.DOMAIN.TLD

When prompted for the root password of the remote host, press <Ctrl-C> to exit the command.

Part 3. Provide your ssh key

This section must be performed for each local user who will access the remote server. Type the following commands to (1) create an ssh private key provided one does not exist, and (2) copy a user public key to the remote server for authentication:

if [ ! -f "$HOME/.ssh/id_rsa" ]; then ssh-keygen; fi
ssh-copy-id `id -un`@HOSTSERVER.DOMAIN.TLD

Now verify that the remote folders will mount:

ls -al /mnt/HOSTSERVER
ls /mnt/HOSTSERVER/`id -un`

Bookmark folders in /mnt/HOSTSERVER in the file manager for easy access.

When this does not work

If the public folder or user home folder will not mount, try the following:

ssh `id -un`@HOSTSERVER.DOMAIN.TLD
chmod og-w ~
chmod og-w ~/.ssh
chmod 600 ~/.ssh/authorized_keys

Mounting File Shares in Windows

Note

Local file sharing to Windows desktops is handled through Microsoft CIFS services, also known as SAMBA in the Linux community. Due to inherent security limitations, SAMBA shares should not be accessed remotely. The secure shell service (ssh) which provides local and remote access with Linux is not supported by Windows. Remote file sharing for Windows desktops generally requires using a VPN instead.

Server SSHFS Configuration

Install authentication and sharing modules on the server as follows:

sudo aptitude install openssh-server libpam-modules

The default server umask=0022 will shade permissions for files and folders created on the server. Private home folders with umask=0077 will work just fine, but public folders needing umask=0007 will result in incorrect permissions which block write access. To prevent this problem:

sudoedit /etc/pam.d/sshd

Now add the following three lines:

# Default umask mask for SSH/SFTP sessions
# Shell sessions: Override with /etc/profile or ~/.bashrc or ~/.profile
session optional        pam_umask.so umask=0000

As noted above, actual ssh shell logins on the server will get the default umask=022 on new files and directories. The following command will change this for all shell logins:

sudo sed -i s/umask 022/umask 0007/ /etc/profile

A logged in user could change just their own default umask with the command:

sudo sed -i s/#umask\ 022/umask\ 0007/ ~/.profile

References:

How to mount SFTP accesses.