dl: download ticket service

dl” is a simple file sharing service for quick/one-off file transfers. Upload a file to get a link you can share. Or create a sharing link to receive files from others. The uploaded files are automatically removed when left unused, requiring zero additional maintenance.

dl” is built for your users: easy to use with any browser, integrates smoothly with Thunderbird for large attachments, works on Android, Windows and OSX or straight from the command line for maximum convenience.


  • PHP 5.5 or higher.
  • PHP SQLite module (or another PDO database module).
  • PHP mbstring module.
  • PHP OpenSSL module.
  • PHP Zip module.
  • Web server access for installation and setup.


The installation is divided into three steps:

  1. Installation of the files
  2. Database creation/setup or database upgrade
  3. Initial user creation

Due to the number of possible configurations, the installation must be carried on manually.

DL installation

  • Copy the htdocs directory contained in the archive to a directory of choice under your web server.

  • Copy include/config.php.dist to either include/config.php or /etc/dl.php and customize as needed. This usually means changing the URL and E-Mail of the service.

  • Ensure the include and style/*/include directories are not directly accessible externally. Type http://dl.example.com/include/config.php and verify that you correctly get an “Access Denied” error.

    If you use Apache, the provided .htaccess files should be already sufficient; consult your web server documentation otherwise.

  • Create a spool directory that will be used by the service to store the files, user and ticket information. This directory should be outside of the document root of your web server. Fix the permissions so that PHP has read/write access to it.

    In the provided include/config.php this is configured as /var/spool/dl. If you web server runs as “nobody:nogroup”, issue:

    mkdir -p -m770 /var/spool/dl
    chgrp nogroup /var/spool/dl

    to create correctly this directory.

  • Create a database (as described in Database setup).

  • Create at least one user (as described in Internal authentication).

Database setup

DL needs a database to store the ticket and user information. By default, DL will use an embedded “sqlite” database stored within the spool directory, but some manual setup is still required.

To create the database, you need the sqlite3 command. On Ubuntu/Debian, sqlite3 can by installed by executing:

sudo apt-get install sqlite3

You should then execute the provided SQL batch for SQLite with the same user as your web server (by using su or sudo if necessary):

cd /var/spool/dl/
sqlite3 data.sdb < /your-installation-directory/include/scripts/db/sqlite.sql
chmod 660 data.sdb

If you want to change the database path, or use a real database server, you need to properly configure the $dsn parameters in include/config.php according to your setup. The DSN string changes according to the PDO module that you want to use. Please see one of:

for the most popular configuration choices. When a username/password is required, using the appropriate variables $dbUser/$dbPassword is preferred instead of embedding the values in the DSN string.

The directory include/scripts/db/ provides SQL initialization scripts for SQLite, MySQL and PostgreSQL.

PHP setup

The following parameters are required to be set in your php.ini:

  • date.timezone: must be set to your system preference.
  • session.auto_start: must be “Off”.

The maximal upload limit is determined by several PHP configuration parameters. Check your php.ini for:

  • upload_max_filesize: change as needed.
  • post_max_size: must be at least 1M larger than upload_max_filesize.
  • session.gc_maxlifetime: must be long enough to allow large uploads to finish.

All the above settings can be configured per-directory and affect only DL. In addition, the following parameters need to be set for the entire PHP server:

  • file_uploads: must be “On”.
  • upload_tmp_dir: ensure enough space is available for temporary files.
  • max_file_uploads: change as needed.

The upload limit as shown in the submission form is determined automatically from the upload_max_filesize parameter.

Any upload beyond post_max_size will be completely ignored: users will get a blank page instead of an error message. You should raise post_max_size above upload_max_filesize to get an acceptable “error window” in old browsers or browsers with JavaScript disabled.

session.gc_maxlifetime (which is in seconds) needs to be long enough for your users to complete a large upload. Uploading 500MB on a slow ADSL connection can take as much as 12 hours, so set it to at least 43200.

If PHP was built as an Apache module you can set per-directory parameters through .htaccess (see http://www.php.net/manual/en/configuration.changes.php) or directly inside your Apache’s configuration (see Apache/mod_php for an example). The provided htdocs/.htaccess contains a reasonable pre-set, but requires AllowOverride All to be set for the directory in your main configuration.

User setup

DL can use both an internal and an external user database, by trusting the authentication credentials provided by your web server.

dl supports both “normal” users and “administrators”. A normal user can only see and manage tickets created by himself. Administrators can see/manage all the tickets.

Internal authentication

Once dl has been installed and PHP is set-up correctly, you have to create at least one user to be able to log in. User management is handled through the command line by using the bundled useradmin.php utility.

On the server, execute the following commands with the same user as your web server (by using su or sudo if necessary):

cd /your-installation-directory/include/scripts
php useradmin.php add "admin" "true" "change me"


  • admin is the user name
  • true (or false) sets the administrator status
  • change me is the password

Repeat as many times as necessary. You should now be able to use the web service. Other users/administrators can be added through the web interface.

External authentication

External authentication should be the preferred form of authentication for corporate use since it supports whatever authentication scheme your web server already supports (for example, LDAP, ActiveDirectory, etc).

To enable external authentication you have to protect the two files:

  • admin.php
  • rest.php

using a “Basic” authentication scheme. You should then set $authRealm to the same authentication realm used in your web server. The other files must not be protected.

DL will implicitly trust the credentials provided by the web server. All users are logged in as “normal” by default. The only setup required is adding the administrators with useradmin.php without using any password.

Logout with HTTP authentication is not guaranteed to work: users should simply close their browser to clear their session (closing a tab or window is not enough in many browsers). Currently, logout works as expected on:

  • Firefox
  • Safari
  • Google Chrome/Chromium

Logout does not work on:

  • Internet Explorer 7/8.
  • Opera 9/10.

Again, only the Basic authentication is supported, which transmits the password in clear-text unless you use SSL.

When using external authentication, the HTTP header USER_EMAIL can additionally provide the user’s default email address. Such header is provided automatically, for example, when using “LemonLDAP::NG”.

Large file support

Large file support (for uploads larger than 2GB) requires a combination of PHP version, web server and browser support.

Apache 2.2 and above support large request bodies but needs to be built for 64bit (see LimitRequestBody). Same for Lighttpd 1.4 (>2gb but only for 64bit builds, see server.max-request-size).

Due to several bugs in PHP prior to 5.6, upload_max_filesize and post_max_size are limited to a 31/32bit integer, which limits the upload size to 2/4GB even on 64bit systems. The maximal uploadable sizes are shown below:

PHP Version Upload limit
<5.4 2gb: post_max_size = 2147483647
5.4-5.5 4gb: post_max_size = 4294967295
>=5.6 no limit

Note that PHP versions before 5.5 are no longer supported, and older versions are shown here for reference purposes only.

Finally, not all browsers support large file uploads:

Browser Upload limit
IE <= 8 2gb
IE >= 9 no limit
Firefox <= 16 2gb
Firefox >= 17 no limit
Chrome no limit
Opera >= 10 no limit


Web-server Configuration


With internal authentication:

<Directory /your-installation-directory>
  AcceptPathInfo On
  AllowOverride Limit
  Options -Indexes
  DirectoryIndex index.php index.html

With external authentication:

<Directory /your-installation-directory>
  # Normal DL configuration
  AcceptPathInfo On
  AllowOverride Limit
  Options -Indexes
  DirectoryIndex index.php index.html

  # Require a Basic authentication scheme for admin/rest.php
  <FilesMatch "^(admin|rest)\.php$">
    # The scheme must be Basic
    AuthType Basic
    AuthName "Restricted Area"
    Require valid-user
    Satisfy any

    # You'll need to provide a valid source for passwords using either the
    # following or some other authentication source (such as LDAP)
    AuthBasicProvider file
    AuthUserFile /path/to/passwd/file

With LDAP or ActiveDirectory authentication:

<Directory /your-installation-directory>
  # Normal DL configuration
  AcceptPathInfo On
  AllowOverride Limit
  Options -Indexes
  DirectoryIndex index.php index.html

  # Require a Basic authentication scheme for admin/rest.php
  <FilesMatch "^(admin|rest)\.php$">
    # The scheme must be Basic
    AuthType Basic
    AuthName "Restricted Area"
    Require valid-user
    Satisfy any

    # Use the LDAP provider (just an example query)
    AuthBasicProvider ldap
    AuthzLDAPAuthoritative off
    AuthLDAPURL ldap://XXXXXX:XXXX/ou=XXXX,dc=XXXX,dc=XXX?sAMAccountName?sub?(objectClass=*)
    AuthLDAPBindDN "cn=XXXX,ou=XXXXX,dc=XXX,dc=XXX"
    AuthLDAPBindPassword "XXXXX"


FastCGI support in Apache up to 2.2.x is severely lacking with all the available modules: mod_fcgi, mod_fcgid (now merged officially into Apache’s mod_fcgi) and mod_fastcgi.

  • mod_fcgi and mod_fcgid buffer the entire request in memory before handing-off the request to PHP, meaning that the maximal upload limit is bound to your available memory at the time of the request, independently of how PHP is setup. This is a known, old bug that’s still present in both mod_fcgi 2.2.14 and mod_fcgid 2.3.4. There is no known work-around: either use mod_php or use a different server.
  • mod_fastcgi has been proved to be slow (and sometimes unstable) in most configurations. It is not advisable to use PHP with mod_fastcgi.

For the REST service to work, independently of the authentication method, mod_rewrite needs to be enabled and configured as follows:

<Directory /your-installation-directory>
  # Normal DL configuration
  AcceptPathInfo On
  AllowOverride Limit
  Options -Indexes
  DirectoryIndex index.php index.html

  <FilesMatch "^(admin|rest)\.php$">
    # Forward the credentials for the PHP process
    RewriteEngine on
    RewriteCond %{HTTP:Authorization} ^(.*)
    RewriteRule ^(.*) - [E=HTTP_AUTHORIZATION:%1]

This is required to correctly pass the Authorization header to the PHP process.

If you want to enable HTTP/External authentication, just add the usual authorization configuration as well:

<Directory /your-installation-directory>
  # Normal DL configuration
  AcceptPathInfo On
  AllowOverride Limit
  Options -Indexes
  DirectoryIndex index.php index.html
  <FilesMatch "^(admin|rest)\.php$">
    # Forward the credentials for the PHP process
    RewriteEngine on
    RewriteCond %{HTTP:Authorization} ^(.*)
    RewriteRule ^(.*) - [E=HTTP_AUTHORIZATION:%1]

    # Require a Basic authentication scheme for admin/rest.php
    AuthType Basic
    AuthName "Restricted Area"
    Require valid-user


PHP/FastCGI works fine with Lighttpd 1.4.x without any special setup. The following configuration is required to protect the include directories:

$HTTP["url"] =~ "^/dl(?:/|/.*/)include/" {
  url.access-deny = ( "" )

You can also enable external authentication with the following:

$HTTP["url"]    =~ "^/dl/(?:admin|rest)\.php$" {
  auth.require  += ( "" => (
      "method"  => "basic",
      "realm"   => "Restricted Area",
      "require" => "valid-user"
  ) )


Nginx in combination with PHP/FastCGI works fine but needs special configuration to setup PATH_INFO correctly. Here is an example configuration with DL installed as a subdirectory in the document root:

location ^~ /dl {
    # Protect the include directories
    location ~ ^/dl(?:/|/.*/)include {
        deny all;

    index index.php index.html;
    try_files $uri $uri/ =404;

    # Enable PHP
    location ~ \.php(?:$|/) {
        include fastcgi_params;

        # Set maximum body size (should be the same as PHP's post_max_size)
        client_max_body_size 512M;

        # Setup PATH_INFO (http://trac.nginx.org/nginx/ticket/321)
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        set $path_info          $fastcgi_path_info;
        fastcgi_param PATH_INFO $path_info;

        try_files $fastcgi_script_name =404;

        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_index index.php;
        fastcgi_pass unix:/var/run/php5-fpm.sock;

Ticket expiration

Ticket expiration can be either performed internally to DL (the default), or by using the external include/scripts/expire.php utility with a cron job. This preference can be set by controlling the $gcInternal parameter.

The internal method requires no setup, but the external method has the added advantage of not interrupting the web interface during the expiration process, and also ensures that the spool is emptied when DL itself is not used actively.

Internal method

Expiration is usually performed aggressively at every page request. You can control this behavior (thus reducing the DB pressure) by tuning the $gcProbability and $gcLimit parameters.

If you notice too much load on your DB, start by lowering $gcProbability to 0.5 and set $gcLimit to roughly the number of active tickets currently present in your DB.

Continue to lower $gcProbability even further until the load becomes acceptable. When the load is acceptable, but queries take too long, reduce $gcLimit.

External method

Simply call include/scripts/expire.php within a cron job, which should be executed with the same user as the web server. Executing the script once a day is sufficient for low traffic websites, but can be executed as often as needed. $gcLimit still controls how many tickets are expired for each run to limit the execution time.

Upgrading from an earlier version

  • Backup your current config.php file and spool directory.

  • Overwrite the DL installation directory with the new copy.

  • Either copy over the old config.php file or customize the new version.

  • Run dbupgrade.php as your web server user:

    cd /your-installation-directory/include/scripts
    php dbupgrade.php
  • Test your new setup.

Internationalization support

DL has been translated in several languages and will attempt to detect the correct locale of the browser and use it automatically when available. If no matching translation can be found, a default will be used, which is configured to be English in the main distribution. The user can however switch the language anytime.

Adding a new translation is easy for anyone familiar with the gettext tools: you don’t need programming knowledge. If you want to contribute a new language, or suggest a better translation, we recommend to subscribe to the mailing list and ask for guidance. We really appreciate your help.

Contributing/updating a translation

Contributing a new translation is easy enough:

  • Edit htdocs/include/lang.php and add your new language name and alias to $langData, as done for the other languages.

  • Execute:

    cd htdocs/include/scripts/

    to freshen the strings to be translated.

  • Translate the generated messages.po in the directory htdocs/include/locale/<locale_NAME>/LC_MESSAGES/ using a text editor, or by using PoEdit, or any other “po” editing tool.

  • Optionally translate the user guide, which is located in htdocs/include/static/guide/.

    Copy the english directory tree into a new tree with the new locale name and translate index.rst. index.html is regenerated automatically.

  • To test/update the translations run langupd.php:

    cd htdocs/include/scripts/


DL should be usable by users without any training. The web interface must be self-explanatory. If you find the usage to be difficult or that the interface could be improved, it’s a bug. Please let us know.

Command-line client: dl-cli

A command-line client to the REST interface is included in the distribution in client/dl-cli.py. This client requires a simple text configuration file, by default stored in ~/.dl.rc, containing the following values:

  • url: REST URL of the service
  • user: your user name
  • pass (optional): your password (if not specified, you will be prompted for it by the client)
  • passcmd (optional): invoke the supplied command to obtain the password
  • verify (optional): “true” or “false”: enable/disable SSL verification (might be required for testing, but defaults to true)
  • email (optional): default email address for grant notifications
  • fingerprint: Validate the server against the specified certificate or fingerprint (See Public key pinning).

An example:


Simply run the command with no arguments to see usage information. At least Python 2.7 is required (with Python 3+ being recommended), with the “PycURL” and “ConfigObj” modules installed. Under Debian/Ubuntu systems you can install the required dependencies by doing the following:

sudo apt-get install python3-pycurl python3-configobj

Graphical client: dl-wx

A graphical client is also included in the distribution, which allows to create tickets easily from the system’s taskbar. The client can be run by executing client/dl-wx/dl-wx.py or by downloading an executable client.

Upon first execution the user will be prompted for the basic configuration. After that all DL functions can be operated through the taskbar icon:

  • Left-clicking on the taskbar will create a new ticket using the default settings.
  • Right-clicking allows to select different actions.
  • On OSX, you can drop files directly on the dock.

At least Python 2.7 is required, with the “ConfigObj”, “PycURL” and “wxPython” modules installed. Under Debian/Ubuntu systems you can install the required dependencies by doing the following:

sudo apt-get install python-pycurl python-configobj python-wxgtk2.8

dl-cli and dl-wx share the same configuration file, so both can be used interchangeably.

A dl-wx pre-built binary is also available online on the dl-wx page, which includes installation instructions and a simple tutorial.

Public key pinning

The fingerprint option in the ~/.dl.rc configuration file implements public key pinning, and supports any value directly accepted by cURL.

It can be a path to a DER/PEM certificate file, or a SHA256 hash of the public key of the host. The hash can be either a hex-encoded string (with optional colon separators), or a string starting with sha256// and followed by a base64-encoded value of the hash.

The quickest way to obtain the fingerprint is to use curl directly:

curl -vkI --pinnedpubkey 'sha256//' https://example.com/

Look for the “public key hash” in the generated output.

Thunderbird integration

The bundled extension “Thunderbird-Filelink-DL” integrates with the new Thunderbird’s Filelink functionality, by using the REST service provided by DL 0.10 and onward. The extension allows to convert large attachments to links automatically, directly within the Composer window.

The extension also allows the user to generate/insert a new upload grant in the current message from the composer window. Both a menu command (under “Tools” .. “Insert upload grant”) and a toolbar item (that you manually need to drag in the composer toolbar) are provided.

To install the extension, go to Thunderbird’s “Tools” .. “Addons” menu, and click on the “Settings” icon just next to the search bar. Select “Install Add-on from file…” and choose the file client/thunderbird-filelink-dl.xpi as provided in the distribution.

See full installation and usage instructions on the extension web page.

General/support mailing list

Go-to list for general discussions, troubleshooting and suggestions. You can subscribe to dl-ticket-service by either sending an empty email to <dl-ticket-service+subscribe@thregr.org> or by using GMane (group “gmane.comp.web.dl-ticket-service.general”). The archives are accessible via web through https://www.mail-archive.com/dl-ticket-service@thregr.org/ or via news directly.
DL release (and release candidate) announcements (read-only list). Very low traffic. To subscribe, send an email to <dl-announces+subscribe@thregr.org>.
Mailing list reserved for translators coordination.

You can contact the main author directly at <wavexx@thregr.org>, though using the general list is encouraged.

Customisation and development

You are encouraged to change DL as you see fit under the terms of the GNU GPL 2 license, or (at your option) any later version. DL’s GIT repository is publicly accessible at:


or at git://src.thregr.org/dl

Development releases

Development releases directly downloaded from git do not include pre-processed files. To build the localization data gettext and docutils need to be installed. You’ll then need to execute:

cd htdocs/include/scripts/

To build the Thunderbird add-on, the Thunderbird SDK needs to be installed as well. You might need to change the paths inside client/thunderbird-filelink-dl/config_build.sh (which is tuned for Debian’s thunderbird-dev package) and execute:

cd client/thunderbird-filelink-dl/

Database schema changes are not gracefully handled while following a development release. Do not run development releases on a production environment.