Simple LAN filesharing with WebDAV

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WebDAV is both a quite popular and yet overlooked way to access and edit files remotely across a wide range of operating systems. Yes it's web stuff, again, but surprisingly fast, lightweight, and that can recover quite well on unstable networks or when the server has to be restarted, or has gone for lunch. A reason why it may be overlooked is possibly because it's often associated with sausage factories like own/nextcloud, or standalone implementations that are not particularly exciting. What is less known is that many web servers come with their own WebDAV implementation. Out of the usual suspects, nginx, Apache, and lighttpd, the latter has both the most lightweight and most complete implementation. No need for anything else!

In these notes we only cover a simple LAN setup, you can build upon it for more complex use case of course.

Server side

Installation

  • This is for Debian, but I know you're smart, you will figure it out for ${FLAVOUR_OF_THE_MONTH_DISTRO}
sudo apt install lighttpd lighttpd-mod-webdav

Example Configuration

Basically the configuration that matters for now are in /etc/lighttpd/conf-available and with symlinks in /etc/lighttpd/conf-enabled. In our simple example we will have three shared folders, one that can be mounted read-only by anyone, and two that are read-write but require a username and password.

  • By default a temp config file called 99-unconfigured.conf provides a generic landing page. We don't need it and we just have to enable the authentication config.
sudo lighttpd-disable-mod unconfigured
sudo lighttpd-enable-mod auth
  • Create a user and password for the read-write share
sudo apt install apache2-utils
sudo htpasswd -c /etc/lighttpd/user.htpasswd turtleprincess heygirl
  • create a new configuration file /etc/lighttpd/conf-available/66-webdav.conf with the following:
server.modules += ( "mod_webdav" )
dir-listing.encoding = "utf-8"
  
# This is needed for keepings tracks of locks and props which
# are needed for shares that can be edited
webdav.sqlite-db-name = "/var/cache/lighttpd/lighttpd.webdav.db"
  
# auth
server.modules += ("mod_authn_file")
auth.backend = "htpasswd" 
auth.backend.htpasswd.userfile = "/etc/lighttpd/user.htpasswd"
auth.require = ( "/readwrite1"     => ( "method" => "basic", 
                                 "realm" => "YOU WOT MATE", 
                                 "require" => "valid-user" ),
                 "/readwrite2" => ( "method" => "basic",
                                 "realm" => "YOU WOT MATE",
                                 "require" => "valid-user" ))
  
# read-only stuff
$HTTP["url"] =~ "^/readonly(?:/|$)" {
    alias.url = ( "/readonly" => "/local/path/to/readonly" )
    dir-listing.activate = "enable" 
    webdav.activate = "enable" 
    webdav.is-readonly = "enable" 
}
 
# shared pit of madness
# for users listed in /etc/lighttpd/user.htpasswd
$HTTP["url"] =~ "^/readwrite1(?:/|$)" {
    alias.url = ( "/readwrite1" => "/local/path/to/readwrite1" )
    dir-listing.activate = "enable" 
    webdav.activate = "enable"
    webdav.is-readonly = "disable" 
}
$HTTP["url"] =~ "^/readwrite2(?:/|$)" {
    alias.url = ( "/readwrite2" => "/local/path/to/readwrite2" )
    dir-listing.activate = "enable" 
    webdav.activate = "enable"
    webdav.is-readonly = "disable" 
}

Now if you wonder what kind of magic will happen so that the lighttpd process, local and remote users can happily live together ever after, and edit the same files, well, none. It won't happen just like this, it does not work and you will be sad. Then you will start binge drinking to forget about server administration. You will go in the streets, pick up fights with strangers who are in a much better physical condition because they don't spend hours configuring neovim plugins that you haven't even used once. It will be painful. So to avoid this unfortunate situation you need to do two things:

  • First, the folder needs to be group-owned by the lighttpd process owner, in our case, on Debian, it's www-data. You also need to set the group ID bit on the folder you intend to use as WedDAV share, so that all newly created files will inherit the group ownership of this folder.
sudo chown regular_user:www-data /local/path/to/readwrite1
sudo chmod g+ws /local/path/to/readwrite1
  • Second, you need to change the way lighttpd is started so that its umask is set in a way that any permission may be set for user and group (default is just user). On a systemd based system (haters gonna hate) you need to edit /etc/systemd/system/lighttpd.service like this:
ExecStart=/bin/sh -c 'umask 002;/usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf'

That's it, you have a working simple LAN filesharing with WebDAV check the documentation for more options, and more fun config time, at home, where it's much safer for you.

Client side

Web browser

The nice advantage of the setup above is that all the files can be readily browsed at the local IP of the machine running lighttpd, for instance http://192.168.100.100/readonly. If you're into web stuff have a look at https://github.com/dom111/webdav-js, it would be really trivial to serve this js file with the lighttpd server and provide more functionality than just browsing and downloading.

Linux filesystem

Mounting a WebDAV on Linux is straightforward with davfs2 and requires minimal configuration. davfs2 is also able to recover quite well from disconnections and potential read/write fuckery (there is a daemon and a local cache, but you don't need to worry about this). If the server is dead, that you need to poweroff your machine, and you still have something mounted, it's a good idea to unmount things first to speed up shutdown. No it won't lock like a little NFS shit but there is a timeout and you're a busy person.

  • To mount manually the read-only folder from above:
sudo apt install davfs2
sudo mount -t davfs http://192.168.100.100/readonly /mnt/readonly
  • To remember username passwords you can create a personal ~/davfs2/secrets file with:
http://192.168.100.100/readwrite1 turtleprincess heygirl
http://192.168.100.100/readwrite2 turtleprincess heygirl
etc
  • You can also have everything configured in your /etc/fstab and then mount everything as a regular user:
# My cool LAN WebDAV thing
http://192.168.100.100/readonly    /mnt/readonly/    davfs  user,uid=username,noauto  0  0
http://192.168.100.100/readwrite1  /mnt/readonly/    davfs  user,uid=username,noauto  0  0
http://192.168.100.100/readwrite2  /mnt/readonly/    davfs  user,uid=username,noauto  0  0

FreeBSD filesystem

On FreeBSD it's basically the same as on Linux. lol. Of course not! What did you think? That would be too easy. You need to work hard to earn your condescending smug BSD coolness. At time of writing, davfs2 is being ported to FreeBSD by its author. Don't hold your breath, but hopefully this will happen because the FreeBSD usual way to mount WebDAV stuff with mount.webdavfs just sucks ("Device not configured" on certain reading operations, not able to recover when the server disconnects). As a workaround, the all-you-can-eat-software-buffet rclone is the only reliable way to have WebDAV mounted in a FreeBSD filesystem.

  • installation
pkg install rclone # yeah yeah you can use portmaster and disable stuff you will regret later
  • load fuse
sudo kldload fusefs
  • to make it permanent add the following to /boot/loader.conf
# Filesystems in Userspace
fusefs_load="YES
  • create a ~/.config/rclone/rclone.conf config file with:
[192.168.100.100]
type = webdav
url = http://192.168.100.100/
vendor = other
user = turtleprincess
pass = SEE_BELOW
  • generate the password with this:
echo "heygirl" | rclone obscure -
  • test if it works
sudo mkdir /mnt/readwrite2
sudo chown user:user /mnt/readwrite2
rclone mount 192.168.100.100:readwrite2 /mnt/readwrite2/ --vfs-cache-mode writes --daemon

You can also make entries in your /etc/fstab

  • rclone can't really be used directly, so we will trick fuse
sudo ln -s /usr/local/bin/rclone /usr/local/bin/mount.rclone
  • in /etc/fstab
# My cool LAN WebDAV thing
192.168.100.100:readonly     /mnt/readonly    fuse noauto,ro,mountprog=/usr/local/bin/mount.rclone
192.168.100.100:readwrite1   /mnt/readwrite1  fuse noauto,rw,mountprog=/usr/local/bin/mount.rclone
192.168.100.100:readwrite1   /mnt/readwrite1  fuse noauto,rw,mountprog=/usr/local/bin/mount.rclone

Nautilus

For those into GUI (not judging, it's a free country) WebDAV is really easy to access thanks to the GVfs daemon. It's also a solid option in terms of recovery and making sure little to no fuckery is possible when writing on an unstable network. In practice, click on the "other" location button on the left pane, choose WedDAV and enter the URL in the form of dav://192.168.100.100/readwrite1 and give your credentials. The only caveat is that the mounted folder name will be the server name, only the server name (IP in this case), so you may want to add your share to the bookmarks, and rename the bookmark to something more meaningful.

Android

Several commercial, closed source options. We don't talk to these people. There are however three interesting FLOSS options:

Nintendo Switch

Because you know, reasons:

Pro Tips

  • IPs are used above but you can use a local DNS or make use of your local /etc/hosts files to give a nice name to your WedDAV server, look into RFC 8375 for pointers.
  • To debug things if things are not behaving as nice things:
lighttpd-enable-mod accesslog
systemctl restart lighttpd
tail -f /var/log/lighttpd/access.log
# 17.4 hours later
# Problem solved at last
lighttpd-disable-mod accesslog
systemctl restart lighttpd
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