SSHFS

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You can use sshfs to mount a remote system - accessible via SSH - to a local folder, so you will be able to do any operation on the mounted files with any tool (copy, rename, edit with vim, etc.).

Installation

Install sshfs from the official repositories.

Mounting

Tip: Google Authenticator can be used with sshfs as additional security.

Before attempting to mount a directory, make sure the file permissions on the target directory allow your user correct access. To mount, invoke sshfs to mount a remote directory:

$ sshfs USERNAME@HOSTNAME_OR_IP:/REMOTE_PATH LOCAL_MOUNT_POINT SSH_OPTIONS

For example:

$ sshfs sessy@mycomputer:/remote/path /local/path -C -p 9876 -o allow_other

Where -p 9876 stands for the port number, -C use compression and -o allow_other to allow non-rooted users have read/write access.

Note: Users may also define a non-standard port on a host-by-host basis in ~/.ssh/config to avoid appending the -p switch here. For more information see Secure Shell#Saving connection data in SSH config.

SSH will ask for the password, if needed. If you do not want to type in the password multiple times a day, read: How to Use RSA Key Authentication with SSH or Using SSH Keys.

Tip: To quickly mount a remote dir, do some file-management and unmount it, put this in a script:
sshfs USERNAME@HOSTNAME_OR_IP:/REMOTE_PATH LOCAL_MOUNT_POINT SSH_OPTIONS
mc LOCAL_MOUNT_POINT
fusermount -u LOCAL_MOUNT_POINT
This will mount the remote directory, launch MC, and unmount it when you exit.

Unmounting

To unmount the remote system:

$ fusermount -u LOCAL_MOUNT_POINT

Example:

$ fusermount -u /mnt/sessy

Chrooting

You may want to jail a (specific) user to a directory by editing /etc/ssh/sshd_config:

/etc/ssh/sshd_config
.....
Match User someuser 
       ChrootDirectory /chroot/%u
       ForceCommand internal-sftp #to restrict the user to sftp only
       AllowTcpForwarding no
       X11Forwarding no
.....
Note: The chroot directory must be owned by root, otherwise you will not be able to connect. For more info check the manpages for Match, ChrootDirectory and ForceCommand.

Helpers

If you often need to mount sshfs filesystems you may be interested in using an sshfs helper, such as sftpman.

It provides a command-line and a GTK frontend, to make mounting and unmounting a simple one click/command process.

Automounting

Automounting can happen on boot, or on demand (when accessing the directory). For both, the setup happens in /etc/fstab.

Note: Be mindful that automounting is done through the root user, therefore you cannot use Hosts configured in .ssh/config of your normal user.

To let root user use an SSH key of a normal user, specify its full path in option IdentityFile.

And most importantly, use each sshfs mount at least once manually while root so the host's signature is added to the .ssh/known_hosts file.

On demand

With systemd on-demand mounting is possible using /etc/fstab entries.

Example:

user@host:/remote/folder /mount/point  fuse.sshfs noauto,x-systemd.automount,_netdev,users,idmap=user,IdentityFile=/home/user/.ssh/id_rsa,allow_other,reconnect 0 0

The important mount options here are noauto,x-systemd.automount,_netdev.

  • noauto tells it not to mount at boot
  • x-systemd.automount does the on-demand magic
  • _netdev tells it that it is a network device, not a block device (without it "No such device" errors might happen)
Tip:

There are two other ways to do this. Both do not require editing /etc/fstab to add a new mountpoint. Instead, regular users can create one by simply attempting to access it (with e. g. something like ls ~/mnt/ssh/[user@]yourremotehost[:port]):

  • autosshfs-gitAUR uses AutoFS. Users need to be enabled to use it with autosshfs-user.
  • afuseAUR is a general-purpose userspace automounter for FUSE filesystems. It works well with sshfs. No user-activation is necessary. Example invocation: afuse -o mount_template='sshfs -o ServerAliveInterval=10 -o reconnect %r:/ %m' -o unmount_template='fusermount -u -z %m' ~/mnt/ssh

On boot

An example on how to use sshfs to mount a remote filesystem through /etc/fstab

USERNAME@HOSTNAME_OR_IP:/REMOTE/DIRECTORY  /LOCAL/MOUNTPOINT  fuse.sshfs  defaults,_netdev  0  0

Take for example the fstab line

llib@192.168.1.200:/home/llib/FAH  /media/FAH2  fuse.sshfs  defaults,_netdev  0  0

The above will work automatically if you are using an SSH key for the user. See Using SSH Keys.

If you want to use sshfs with multiple users:

user@domain.org:/home/user  /media/user   fuse.sshfs    defaults,allow_other,_netdev    0  0

Again, it is important to set the _netdev mount option to make sure the network is available before trying to mount.

Secure user access

When automounting via /etc/fstab, the filesystem will generally be mounted by root. By default, this produces undesireable results if you wish access as an ordinary user and limit access to other users.

An example mountpoint configuration:

USERNAME@HOSTNAME_OR_IP:/REMOTE/DIRECTORY  /LOCAL/MOUNTPOINT  fuse.sshfs noauto,x-systemd.automount,_netdev,user,idmap=user,transform_symlinks,identityfile=/home/USERNAME/.ssh/id_rsa,allow_other,default_permissions,uid=USER_ID_N,gid=USER_GID_N 0 0

Summary of the relevant options:

  • allow_other - Allow other users than the mounter (i.e. root) to access the share.
  • default_permissions - Allow kernel to check permissions, i.e. use the actual permissions on the remote filesystem. This allows prohibiting access to everybody otherwise granted by allow_other.
  • uid, gid - set reported ownership of files to given values; uid is the numeric user ID of your user, gid is the numeric group ID of your user.

Options

sshfs can automatically convert your local and remote user IDs.

Add the idmap option with user value to translate UID of connecting user:

# sshfs -o idmap=user sessy@mycomputer:/home/sessy /mnt/sessy -C -p 9876

This will map UID of the remote user "sessy" to the local user, who runs this process ("root" in the above example) and GID remains unchanged. If you need more precise control over UID and GID translation, look at the options idmap=file and uidfile and gidfile.

Troubleshooting

Checklist

Read the SSH Checklist Wiki entry first. Further issues to check are:

1. Is your SSH login sending additional information from server's /etc/issue file e.g.? This might confuse SSHFS. You should temporarily deactivate server's /etc/issue file:

$ mv /etc/issue /etc/issue.orig

2. Keep in mind that most SSH related troubleshooting articles you will find on the web are not Systemd related. Often /etc/fstab definitions wrongly begin with sshfs#user@host:/mnt/server/folder ... fuse ... instead of using the syntax user@host:/mnt/server/folder ... fuse.sshfs ... x-systemd, ....

3. Check that the owner of server's source folder and content is owned by the server's user.

$ chown -R USER_S: /mnt/servers/folder

4. The server's user ID can be different from the client's one. Obviously both user names have to be the same. You just have to care for the client's user IDs. SSHFS will translate the UID for you with the following mount options:

uid=USER_C_ID,gid=GROUP_C_ID

5. Check that the client's target mount point (folder) is owned by the client user. This folder should have the same user ID as defined in SSHFS's mount options.

$ chown -R USER_C: /mnt/client/folder

6. Check that the client's mount point (folder) is empty. By default you cannot mount SSHFS folders to non-empty folders.

7. If you want to automount SSH shares by using an SSH public key authentication (no password) via /etc/fstab, you can use this line as an example:

USER_S@SERVER:/mnt/on/server      /nmt/on/client        fuse.sshfs      x-systemd.automount,_netdev,user,idmap=user,transform_symlinks,identityfile=/home/USER_C/.ssh/id_rsa,allow_other,default_permissions,uid=USER_C_ID,gid=GROUP_C_ID,umask=0   0 0

Considering the following example settings ...

SERVER = Server host name (serv) USER_S = Server user name (pete) USER_C = Client user name (pete) USER_S_ID = Server user ID (1004) USER_C_ID = Client user ID (1000) GROUP_C_ID = Client user's group ID (100)

you get the client user's ID and group ID with

$ id USERNAME

this is the final SSHFS mount row in /etc/fstab;

pete@serv:/mnt/on/server      /nmt/on/client        fuse.sshfs      x-systemd.automount,_netdev,user,idmap=user,transform_symlinks,identityfile=/home/pete/.ssh/id_rsa,allow_other,default_permissions,uid=1004,gid=1000,umask=0   0 0

8. If you know another issue for this checklist please add it the list above.

Connection reset by peer

  • If you are trying to access the remote system with a hostname, try using its IP address, as it can be a domain name solving issue. Make sure you edit /etc/hosts with the server details.
  • If you are using non-default key names and are passing it as -i .ssh/my_key, this will not work. You have to use -o IdentityFile=/home/user/.ssh/my_key, with the full path to the key.
  • If your /root/.ssh/config is a symlink, you will be getting this error as well. See this serverfault topic
  • Adding the option 'sshfs_debug' (as in 'sshfs -o sshfs_debug user@server ...') can help in resolving the issue.
  • If that doesn't reveal anything useful, you might also try adding the option 'debug'
  • If you are trying to sshfs into a router running DD-WRT or the like, there is a solution here. (note that the -osftp_server=/opt/libexec/sftp-server option can be used to the sshfs command in stead of patching dropbear)
  • Old Forum thread: sshfs: Connection reset by peer
  • Make sure your user can log into the server (especially when using AllowUsers)
  • Make sure Subsystem sftp /usr/lib/ssh/sftp-server is enabled in /etc/ssh/sshd_config.
Note: When providing more than one option for sshfs, they must be comma separated. Like so: 'sshfs -o sshfs_debug,IdentityFile=</path/to/key> user@server ...')

Remote host has disconnected

If you receive this message directly after attempting to use sshfs:

  • First make sure that the remote machine has sftp installed! It will not work, if not.
Tip: If your remote server is running OpenWRT: opkg install openssh-sftp-server will do the trick
  • Then, try checking the path of the Subsystem listed in /etc/ssh/sshd_config on the remote machine to see, if it is valid. You can check the path to it with find / -name sftp-server.

For Arch Linux the default value in /etc/ssh/sshd_config is Subsystem sftp /usr/lib/ssh/sftp-server.

Freezing apps (e.g. Nautilus, Gedit)

Note: This prevents the recently used file list from being populated and may lead to possible write errors.

If you experience freezing/hanging (stopped responding) applications, you may need to disable write-access to the ~/recently-used.xbel file.

# chattr +i /home/USERNAME/.local/share/recently-used.xbel

See the following bug report for more details and/or solutions.

Shutdown hangs when sshfs is mounted

Systemd may hang on shutdown if an sshfs mount was mounted manually and not unmounted before shutdown. To solve this problem, create this file (as root):

/etc/systemd/system/killsshfs.service
[Unit]
After=network.target

[Service]
RemainAfterExit=yes
ExecStart=-/bin/true
ExecStop=-/usr/bin/pkill sshfs

[Install]
WantedBy=multi-user.target

Then enable the service: systemctl enable killsshfs.service

See also