#summary Authentication via external script/process
#labels Stage-Alpha,Type-Auth

= Introduction =

Allow client authentication to be handled by an external script/process.

= Installation =

mod_auth_external depends on a Lua module called [http://www.tset.de/lpty/ lpty]. You can install it on many platforms using [http://luarocks.org/ LuaRocks], for example:

{{{
   sudo luarocks install lpty
}}}

Note: Earlier versions of the module did not depend on lpty. While using the newer version is strongly recommended, you can find the [https://prosody-modules.googlecode.com/hg-history/50ee38e95e754bf1034d980364f93564028b2f34/mod_auth_external/mod_auth_external.lua older version here] if you need it (revision 50ee38e95e75 of the repository).

= Configuration =

As with all auth modules, there is no need to add this to modules_enabled. Simply add in the global section, or for the relevant hosts:

{{{
    authentication = "external"
}}}

These options are specific to mod_auth_external:

||external_auth_protocol||May be "generic" or "ejabberd" (the latter for compatibility with ejabberd external auth scripts. Default is "generic".||
||external_auth_command||The command/script to execute.||

Two other options are also available, depending on whether the module is running in 'blocking' or 'non-blocking' mode:
||external_auth_timeout||blocking||The number of seconds to wait for a response from the auth process. Default is 5.||
||external_auth_processes||non-blocking||The number of concurrent processes to spawn. Default is 1, increase to handle high connection rates efficiently.||

== Blocking vs non-blocking ==

Non-blocking mode is automatically activated when:

  * Running Prosody trunk ([http://prosody.im/nightly/ nightly] build 414+).
  * [http://prosody.im/doc/libevent libevent] is enabled in the config, and LuaEvent is available.
  * lpty (see installation above) is version 1.0.1 or later.

= Protocol =

Prosody executes the given command/script, and sends it queries.

Your auth script should simply read a line from standard input, and write the result to standard output.
It must do this in a loop, until there's nothing left to read. Prosody can keep sending more lines to the script,
with a command on each line.

Each command is one line, and the response is expected to be a single line containing "0" for failure or "1" for success.
Your script must respond with "0" for anything it doesn't understand.

There are three commands used at the moment:

== auth ==
Check if a user's password is valid.

Example: {{{auth:username:example.com:abc123}}}

Note: The password can contain colons. Make sure to handle that.

== isuser ==
Check if a user exists.

Example: {{{isuser:username:example.com}}}

== setpass ==
Set a new password for the user. Implementing this is optional.

Example: {{{setpass:username:example.com:abc123}}}

Note: The password can contain colons. Make sure to handle that.

== ejabberd compatibilty ==
ejabberd implements a similar protocol. The main difference is that Prosody's protocol is line-based, while ejabberd's is length-prefixed.

Add this to your config if you need to use an ejabberd auth script:
{{{
	external_auth_protocol = "ejabberd"
}}}

= Compatibility =
||0.8||Works||
||0.9||Works||