Monday, December 12, 2011

How To Install Additional Software On Your Home Router (DD-WRT)

Have you ever wanted to have additional functionality like Email, Bit-torrent or even MySQL directly on your router? Well maybe now you can. How-To Geek dives into how-to install Opkg software on DD-WRT.
Image by Jean Spector and Aviad Raviv
If you haven’t already, be sure and check out the three previous articles in the series:
Assuming you are familiar with those topics, keep reading. Keep in mind that this guide is a little more technical, and beginners should be careful when modding their router.


I’ve recently bought a new Buffalo WZR-HP-AG300H which comes with a re-branded version of DD-WRT. Due to the fact that this router has a USB port, I immediately connected an HD and tried to use the “Optware, The Right Way” wiki guide. Unfortunately I’ve quickly found that the router that I got, is Atheros based and the script from that wiki page, doesn’t support it. So I’ve started digging (as i always do) and came across several guides (1,2 and 3) that aimed to explain how to get Opkg working manually. While their contribution (among other sources on the web) to this guide was invaluable, some of the instructions are (IMHO) simply not straight forward enough. For example, giving you the “lib” files fish, but don’t teach you how to fish it from the source. Also having to make use of a Linux formatted HD or at least a partition of one (which actually doesn’t even work on the firmwares I’ve tested with). That is why, I felt the need to create the below concise, simple to follow and reproducible procedure for getting the OpenWRT Opkg package manager to work on such routers.

What is Opkg?

Opkg is a package manager like apt/aptitude and yum. It acts as a replacement for the Ipkg package manager, and can be used to install software such as: the Transmission BitTorrent daemon, the ssmtp email sender and Knockd a daemon that execute scripts after a specified port triggering sequence, to name a few. From the OpenWRT site:
The opkg utility (an ipkg fork) is a lightweight package manager used to download and install OpenWrt packages from local package repositories or ones located on the Internet. Opkg attempts to resolve dependencies with packages in the repositories – if this fails, it will report an error, and abort the installation of that package.
So using Opkg we can install things like we did with Ipkg on the “Unleash Even More Power from Your Home Router” guide. The major differences, are:
  1. In order to give the examples of SSMTP and Knockd, yours truly, had to figure out the dependencies manually. The procedure to do this manually is bothersome and not very straight forward. Opkg does this automatically.
  2. This time we will be adding software on top of the firmware that’s in place, rather then replacing it. While replacing it was an excellent geek exercise, it was without a doubt: dangerous, prone to problems, irreversible and worst of all router specific. Needless to say that this is way simpler and safer.


In order to complete this guide note the following:
  1. As stated above, this guide was created and tested on Buffalo WZR-HP-AG300H with Buffalo’s “Pro” firmware version 17135. It should work on any Atheros (ar71xx) based routers with any version of DD-WRT of the same revision or above, but your mileage may very.
  2. You will need to enable SSH on the router, as well as install and use WinSCP  to connect to it. This was explained in the “How to Remove Advertisements with Pixelserv on DD-WRT” guide. In fact, it will be assumed that you are able to do everything that is explained in that guide.
  3. You need to be able to connect to the router using a terminal (SSH is recommended). Some pointers on how to do this, are on the DD-WRT wiki.
  4. Space for JFFS and about 4MB of post formatted space for the base setup. JFFS space is not only a prerequisite, it is a show stopper. This is because, If your router doesn’t have at least the above mentioned 4MB of post formatted space, you will not gain any real benefit from this guide, and will be better off using the “Unleash Even More Power from Your Home Router” guide to install Ipkg packages directly into the firmware or installing the Ipkg packages manually. Follow the instructions on the “How to Remove Advertisements with Pixelserv on DD-WRT” guide to enable JFFS, and see how much free space you actually have after it is formatted.
Note: It is possible to do this with only 2MB of space for the setup, but then we would lose the upshot of “/etc” becoming read-writable and would have to invoke Opkg, while specifying the configuration file manually every time… which is like sooo lame… 

Lets get cracking

At this point you should have enabled JFFS and are able to SSH/WinSCP into the router.
  1. Open a terminal session to the router.
  2. Create a temporary directory that we will be working in:
    mkdir /tmp/1
    cd /tmp/1
Use Ipkg to install Opkg
While we are going to replace Ipkg as the package manager, we will be using it to manually install the Opkg installation package.
  1. To do this, download the Opkg installation package for the ar71xx architecture from the OpenWRT project trunk:
    Note1: At the time of this writing, 618 is the latest version, this may be subject to change in the future, so adjust accordingly.
    Note2: It may be possible that the only difference in getting this guide to work for other architectures is to get the Opkg installer from the applicable architecture for your router… however this is untested by yours truly.
  2. Invoke Ipkg to manually install Opkg using:
    ipkg install opkg_618-2_ar71xx.ipk
    Note: You can, if you wanted too, install every package in the repository manually this way. However this would mean that you will have to resolve the dependencies on your own… and what would be the fun in that?
Obtaining the dynamic library files (“lib”s)
The required “lib” files to make Opkg work, are part of the OpenWRT distribution. To obtain them, one has to extract them from the “Root FileSystem” of said distribution.
  1. To do This, download the latest basic “Root FileSystem” for the openWRT distrebution which containes the required “lib”s from the OpenWRT project trunk:
  2. Extract it using:
    tar xvzf openwrt-ar71xx-generic-rootfs.tar.gz
  3. Copy the “libs” files from the “rootfs” we’ve extracted above to the “libs” directory on our JFFS, while preserving their attributes and symbolic links:
    cp -Pp /tmp/1/lib/* /jffs/usr/lib/
    Note: You will get messages saying that the sub-directories are being omitted. As we don’t need anything but the “lib” files, this is fine and you can safely ignore these messages.
Fixing the LD_LIBRARY “PATH”
We need to tell the router, where to look for the shared libraries (libs) we’ve just “installed” and that it needs to do this before the ones that came with the firmware.
  1. To do this set the LD_LIBRARY environment variable manually (for now), to make it so the location where we copied the new lib files will be the first one in the “PATH”:
    export LD_LIBRARY_PATH=/jffs/usr/lib:$LD_LIBRARY_PATH
Read-writable “/etc”
We are going to copy “/etc” to JFFS and then make the regular “/etc” mount point, point to it. Doing so, will both open up a world of possibilities, because “/etc” will become read-writeable (which I personally have been waiting for give or take 7 years now) and enable packages that expect this behavior, to work correctly.
  1. Create the directory that will hold “/etc”:
    mkdir -p /jffs/geek/etc
  2. Recursively copy the entirety of “/etc” while preserving all subdirectories, file attributes and symbolic links.
    cp -a /etc/* /jffs/geek/etc/
  3. Manually (for now) “bind mount” the “/etc” directory to the JFFS one:
    mount -o bind /jffs/geek/etc/ /etc/
Set the Optware directory (“/opt”)
Opkg from OpenWRT, expects to be used when the router’s firmware is built. As at such time, the FileSystem isn’t on the router yet, and thus still subject to change, there is no problem installing to any location on the FileSystem. That is why the Opkg configuration file points packages to install to the “root” (/) of the FileSystem. However, we are using Opkg after the firmware was built and installed on the router, and as we can’t change the root of the filesystem to be read-writeable, we will point all installations to be installed under “/opt”. However Currently “/opt” also points to a read-only location on the router’s firmware. To overcome this, we will make “/opt” point to JFFS, which is read-writable.
  1. To do this, Create the directory that will contain the Optware packages:
    mkdir -p /jffs/opt
  2. Manually (for now) “bind mount” the “/opt” directory to the JFFS one:
    mount -o bind /jffs/opt/ /opt/
    Note: While beyond the scope of this guide, more advanced users may want to change this mount point, to point to an HD.
Adjusting the Opkg configurations file
We want the Opkg configuration file to be where Opkg searches for it by default (which is “/etc”) and adjusted to install to “/opt”.
  1. To do this, move the opkg configuration file installed by the Opkg package to the read-writable “/etc” location:
    mv /jffs/etc/opkg.conf /etc/
  2. Change the destination for Optware installations to be “/opt” instead of “root” (/).
    To do this, with the “vi” editor or WinSCP navigate to “/etc/” and make the “opkg.conf” file’s content look like:
    src/gz snapshots
    dest root /opt
    dest ram /tmp
    lists_dir ext /var/opkg-lists
    option overlay_root /overlay
    Note: You can change the “lists_dir” directive to point to a location that isn’t in RAM, but rather on JFFS. While this would relieve you from updating the lists, before you can install additional software (if your router is rebooted from the last time), you would lose about 1.5MB of the scarce JFFS space and you would be compounding to its erosion.
Hello baby
You should be able to see that Opkg is working by issuing the update and lists commands.
  1. If all went well you should be seeing that the Opkg lists have been updated without error and you are ready to implement the script in the next step:
    opkg update; opkg list
  2. Take the time to start exploring the packages available on the repository….
StartUp script
We now need to make it so all of the required mounting and path-ing will happen automatically when the router boots. To that end, we’ve created for you, this initialization geek-init script.
  1. Download, then extract it and place it under “/jffs/geek/etc/”. (Consider doing this with WinSCP).
  2. Make the script executable by going into its properties with WinSCP or executing:
    chmod +x /jffs/geek/etc/
  3. Make the script execute on the router’s startup, using the WebGUI. Under Administration -> Commands, in the text box, put:
    /jffs/geek/etc/ web-gui
    And Click “Save Startup”.
Kicking the tires
If all went well, you should now be able to reboot the router and still use the Opkg package manager. That is to update, list and install applications.
Lets test that everything is working by installing the “netstat” command, which for some reason has been omitted from DD-WRT’s builds lately. Before we do this, execute the netstat command in the terminal and you will see that you’re grated by an error from the shell, saying “-sh: netstat: not found”.
  1. Your first step will always be, to update the Opkg lists, as to have the latest packages listing from the repository:
    opkg update
  2. If you don’t know which package contains the “netstat” command, you can filter the results using.
    Opkg list | grep netstat
  3. And now install “netstat” using:
    opkg install net-tools-netstat
    And now, when you execute the netstat command again it works… neat ha? :)
Until the future articles in which we will install and configure software packages using this method, may you have tons of geek fun exploring the vast amount of software that is now right at your finger tips.