====== How to fun_plug ======
Creating a ''fun_plug'' file on your hard disk allows you to run a custom boot script. 
This feature allows additional software to run on the DNS-323.

The most popular fun_plug implementation is [[http://www.inreto.de/dns323/fun-plug/|Fonz fun_plug]]. 
For a good set of tutorial see [[howto:ffp]].

===== How fun_plug works: ===== 
When the DNS-323 boots it reads ''[[information:dlink_files:102b114:etc:initab|/etc/inittab]]'' which will execute the ''[[information:dlink_files:102b114:etc:rc.sh|/etc/rc.sh]]'' script, just as the [[http://dns323.kood.org/dsmg600/howto:fun_plug|DSM-G600]]: 
<code bash>
::sysinit:/etc/rc.sh
</code>
This file will mount your disks and startup daemons running on the unit.

The last thing that happens is the //magic// we use to get access to the unit. 
This is what makes the [[wp>Black_box_(systems)|black box]] a white box.

What happens is that the ''[[information:dlink_files:102b114:etc:rc.sh|/etc/rc.sh]]'' script calls the ''[[information:dlink_files:102b114:usr:sbin:chk_fun_plug|/usr/sbin/chk_fun_plug]]'' script:
<code bash>
/usr/sbin/chk_fun_plug &
</code>

The ''[[information:dlink_files:102b114:usr:sbin:chk_fun_plug|/usr/sbin/chk_fun_plug]]'' script itself will check the mounted disk ''/mnt/HD_a2'' for presence of a file called ''fun_plug'' and execute it if there.

<box center|DNS-323 Boot Process>{{:dns-323_boot.gif|DNS-323 Boot Process}}
</box>

As this file is located in one of the inserted disks we can place our own file there and 
get access to the unit, most likely through [[telnet]].



===== Installing a fun_plug =====
There are many ways to achieve this, but all of them includes creating the file. The file we use here is a very simple fun_plug which only prints some system startup information into another file:

<code bash>
#!/bin/sh
#
# Simple fun_plug
#
dmesg > /mnt/HD_a2/dmesg.out
</code>

Next step is to transfer this file and give it proper rights, i.e. the right to execute.




==== Transfer using FTP ====

  - Enable FTP through the admin pages and set up an ftp user.
  - Create a test fun_plug file on your system.
  - Connect to your DNS-323 using a command line ftp client (in windows: start / run / ftp)
  - Change to the root directory: cd /
  - Upload your fun_plug: ''put fun_plug''
  - Make it executable: chmod 777 fun_plug
  - If command prompt doesn't recognize 'chmod', use 'quote site chmod 777 fun_plug'
  - Quit ftp: quit


----

**NOTE For v1.03+**
From the [[information:beginner_s_faq|Beginner's FAQ]]:
''Q: Where does it go?
A: The fun_plug file needs to be in your root directory where you can see it when you access the network drive. When using 1.03 firmware for example that location would be inside the directory called “Volume_1”''

----



==== Transfer using SMB mounted drives ====
  - Create a test fun_plug on your system.
  - FW 1.01: Create the test fun_plug on \\NAS\HDD_1
  - FW 1.02: Create the test fun_plug on \\NAS\Volume_1

Version 1.01 and 1.02 have proper umask set so the files //should// have proper rights. But; better to be safe than sorry and ftp to your unit and make sure the file has at least ''rwx------'' rights.

Windows users should note that the fun_plug file must be in unix file format (LF for newline) and not in Windows (CR LF for newline). One suggested editor for Windows is UltraEdit or Notepad++ which let you save the file in both formats.


==== Creating one from a serial connection ====

  - With a [[hardware:serial|serial connector]] on your unit, break into shell by issuing **5784468** at the prompt. 
  - Change directory to /mnt/HD_a2
  - Create the fun_plug using "echo dmesg >> /mnt/HD_a2/fun_plug"


==== Inserting one using an external system ====
See the instructions for [[http://dns323.kood.org/dsmg600/howto:fun_plug|DSM-G600]]. 


==== File Permissions ====

An important point in the fun_plug installation. The "fun_plug" file on the device needs to have the executable permissions. Otherwise known as 777 for the chmod command. This will give it read write and execute by all users on the system.

This is achieved by executing the chmod command (given below) from the directory of the fun_plug.

chmod 777 fun_plug 

The key is being able to do this. In earlier versions of the D-Link firmware, this could be done through ftp. All one had to do is set-up an account with read write permissions. Then through a command line version of an ftp client one could execute this command.

The D-Link firmware version 1.09 does not allow FTP users to change permissions. However the earlier version 1.06 does. If users are stuck with changing permissions, you should install firmware 1.06. Then proceed to install fun_plug. If the user wants features in the latest firmware they can still upgrade and retain fun_plug functionality provided that the fun_plug script has kept the executable permissions.


===== What's Next =====
So; you have a fun_plug working and want to do something with it. Start with [[telnet]] and maybe a [[chroot_debian|debian]] Sarge chroot system. Upgrade your [[firefly|iTunes server]] or make your ftp server working in a [[open_ports_ftpd|NAT]]'ed environment.

For a comprehensive list of what you can do with your DNS-323 take a look at the [[howto:ffp| howtos list]].

But remember, always have //fun//, ;-), and be aware that you're now in a position where you can easily [[wp>bricked|brick]] your unit.

===== Having issues? =====
Visit out our [[information:Beginner's FAQ]] for more information about what to do.

A simple step by step description can be found here: [[Simple fun_plug StepByStep]]