UPDATE: LUFS AND SHFS are deprecated in favor of SSHFS. I still left the description below

Suppose that you want to mount a filesystem on a remote computer sitting somewhere on the internet. There are two standard ways to do this in Linux:

NFS (Network FileSystem) - the standard UN*X way
Samba (SMB/CIFS/Microsoft Windows Networking) - can be handy. Samba is a good Linux tool for setting up Microsoft networking

NFS is nice: it's fast, it's standard, etc. Unfortunately, there are drawbacks to NFS, at least as far as I can tell:

1) You will need FULL access to both systems in order to configure them to use NFS - this means that you will need to be root on both systems

2) Both systems need to be able to talk to each other directly without being impeded by firewalls, gateways, etc. This isn't going to work in my case (and probably in yours) where my computer is not directly on the internet, but instead is behind a router and firewall. Nevertheless, there ARE machines on the internet with filesystems that I really want to mount (not really, but in principle).

3) I have experienced machine crashing when one side of the link goes down. In other words, if one machine is expecting the other machine to be there, and it isn't... BOOM... good luck regaining control. Note that this happens to me whether I use so-called "hard" or "soft" mount options.

4) Neither NFS nor Samba is particulary secure. I would never dare set up a share without being behind a firewall. Even then I'm a bit scared.

The Alternatives: SSHFS LUFS and SHFS
There ARE alternatives to NFS and Samba, and I will document two of them here - namely lufs and shfs. UPDATE: added SSHFS. The beauty is that they use your favorite secure networking tool - ssh! Everybody loves ssh... it's great. Personally I find that SHFS SSHFS is more usable now the only choice.

First, a brief comment is in order. Since you will be using ssh, you might want to use ssh authentication. This will allow you to login to a remote computer without having to type your password every time. I use it, and I'm quite happy with it (especially since it is still secure).

Obviously you will need to be the root user (but only on the local machine) to do ALL of the following.

Both LUFS and SHFS and SSHFS are kernel modules (in addition LUFS utilizes a "user space" daemon), so you will need to download the module source and compile it. Before you can do that, however, you will need to make sure that your "kernel headers" are installed (if you compiled your own custom kernel then don't worry about it).

If you are running a stock Debian kernel then use "apt-get" to install your relevant kernel headers package. The following command will do this for you:

apt-get install linux-headers-`uname -r`

The *BETTER* way to do this is to just compile your own custom kernel from source - then you won't need these silly headers if you keep your source directory around.

If you are using Debian, then you will also want to install the package

module-assistant

SSHFS (Replacement for LUFS and SHFS)
Now it's time to get a hold of the SSHFS utilities and the FUSE kernel module (which you will have to compile). In Debian just apt-get the packages:

sshfs
fuse-utils
fuse-source

The remainder of this document will assume that you are using Debian. Now you will need to compile and install the FUSE module. This can be achieved by issuing the following two commands

module-assistant build fuse
module-assistant install fuse

modprobe fuse

Now add the privileged users to the group "fuse" (just edit the file /etc/group and add your username). You probably need to log out and log back in for the settings to take effect.

That's IT!!! For example, to mount the directory "/remote/directory" which is located on the (remote) computer remotecomputer.com, I would issue the command

sshfs username@remotecomputer.com:/remote/directory /local/directory

fusermount -u /local/directory

TIP: Note that using the "home" directory designation "~/" in place of "/remote/directory" does not seem to work. Instead you will probably be forced to use the full path for remote directories.

LUFS (Linux Userspace FileSystem)
DEPRECATED... USE SSHFS INSTEAD Now it's time to get a hold of the LUFS utilities and the LUFS kernel module (which you will have to compile). You can either go to the original website, or (if you are using Debian) then you can just apt-get the packages:

lufs-source
lufs-utils

There used to be an "lufs-crytofs" package - I don't know if encryption has been included into the other packages. That might be kind of cool to look at.

The remainder of this document will assume that you are using Debian. Now you will need to compile and install the LUFS module. This can be achieved by issuing the following two commands

module-assistant build lufs
module-assistant install lufs

That's IT!!! It should work right out of the box now! So, for example, to mount the directory "/remote/directory" which is located on the (remote) computer remotecomputer.com, I would issue the command

lufsmount sshfs://username@remotecomputer.com/remote/directory /local/directory

Note that using the "home" directory designation "~/" in place of "/remote/directory" does not seem to work. Instead you will probably be forced to use the full path for remote directories.

At this point you might want to allow users (other than root) to be able to use the "lufsmount" and "lufsumount" utilities. You will need to change the "suid" flag on the binaries "/usr/bin/lufsmount" and "/usr/bin/lufsumount" by issuing the following commands (as root)

chmod +s /usr/bin/lufsmount
chmod +s /usr/bin/lufsumount

SHFS
DEPRECATED... USE SSHFS INSTEAD This is another project which implements the same thing, with a few differences. First, it runs only as a kernel module (whereas LUFS actually runs as a kernel module AND in "user space"). This means that SHFS is likely faster than LUFS, but LUFS is more flexible.

The installation will be almost identical. First you will need to apt-get the Debian packages

shfs-source
shfs-utils

When you get these packages, you will be prompted to "suid" the shfs utils so that ANY user will be able to mount and unmount. Note that for LUFS above you needed to do this manually. Apparently the SHFS package maintainers already thought this through, which is kind of nice. I obviously said "yes" since I trust all of my users (I'm lucky).

Now I just have to build and install the module by issuing the following commands (in Debian)

module-assistant build shfs
module-assistant install shfs

That's IT! Now to mount the remote directory I just type

shfsmount username@remotecomputer.com /local/directory

Clearly this mounts username's home directory (on the remote machine) onto /local/directory (on the local machine). I can actually specify any remote directory that I want by using the command

shfsmount username@remotecomputer.com:/remote/directory /local/directory

In some sense, I feel that SHFS is better if you just want to use SSH for a standard filesystem mount. It's simpler (although not much, I admit). LUFS, however, seems far more flexible and has a lot of fun toys (which I will need to check out in the future... like encrypted filesystems).

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