Category Archives: Linux

Python Curses – Custom Progress Bar

Custom Progress BarIn making a visual editor for my XFDL project, I’ve decided to do the basic start in curses.  This is a module of python/library of C that I have not been able to utilize much at this point despite interest.  Unfortunately, there seems to be limiteexid documentation beyond the standard ‘Hello World’ type of program.  I’ll write this short tutorial with the assumption you can get through those tutorials and utilize this object.

The concept here is to create a progress bar in curses.  This example does not have any data but a basic understanding of python would allow you to create the refreshes on percentage of completion rather than time based as I have here.

def show_progress():
    #Create a window object.
    win = curses.newwin(3,32,14,10)
    # Add the Border
    # Current text: Progress
    win.addstr(1,1,"Progress ")
    # This is to move the progress bar per iteration.
    pos = 10
    # Random number I chose for demonstration.
    for i in range(15):
        # Add '.' for each iteration.
        # Refresh or we'll never see it.
        # Here is where you can customize for data/percentage.
        # Need to move up or we'll just redraw the same cell!
        pos += 1
    # Current text: Progress ............... Done!
    # Gotta show our changes.
    # Without this the bar fades too quickly for this example.

See, nothing to it.  The first line creates a new window object for and the next line adds its border.  I mapped out the relative positions for text, and you’ll want to customize this to what you need to use in your program, but for the sake of demonstration, it will show a period for each iteration.  As previously stated, you can customize this to be data or percentage driven in your program.  Don’t forget to call win.refresh() for each iteration you want to show on the screen!

XFDL in Linux :: Part 2

More for the ongoing series of producing an XFDL viewer in Linux.  In the previous tutorial, we decompressed an XFDL file, although I have had trouble recompressing the file.  It turns out that I need to do some experimentation and find the exact compression method used in gzip to be able to make the form readable.  That will be for the next update though.  I thought I would give a short preview of what’s next on this.

An XFDL file is an XML (xform) by IBM meant to run through their interpreter. IBM has some great documentation on this format.  PureEdge works much like a browser does to decompress the file by Mime-type and to then parse and read the file, including embedded binaries (for pictures, files, etc) and embedded coding (custom functions).  My interpreter will have a long ways to go so I’ll be happy to just be able to place my values in the correct fields.  I’m re-reading XML parsing within Python to make this an easy function, so be patient on that part.  But for those eager to see what I’m talking about, I’ve pasted a small section of XML from a decompressed XFDL.

      <field sid="NAME">
            <ae>Times New Roman</ae>
         <acclabel>d ay form 46 44-r, december 19 82.
ay p d. p e version 1.00.
edition of 1 august 19 77 is obsolete.
army reserve reenlistment data.
for use of this form, see ay r 1 40-1 11, the proponent agency is r c p ay c.
item 1. enter name using last name comma first name comma middle initial format.</acclabel>
As you can see, there is a <value> tag for these nodes.  For my next post, I’ll write some python code to break this xml to an object that can print the label and insert a value into the xml.  There is a lot of work to interpret the embedded items, code and other tags, but this will be a start!

XFDL in Linux :: Part 1

Earlier, I wrote about using PureEdge Viewer, which is Windows software from IBM on Linux through Wine. This got me thinking, do we need to use Windows software. A quick look at the file and through Google and it’s easy to see that an *.xfdl file is a gzipped, base64 encoded xml file. So this is part one of what I hope to be a tutorial into designing software on Linux using python to open, read and write xfdl files in the same way as PureEdge Viewer. It gets annoying, to say the least, to need to open Windows in VirtualBox, or an actual install to read and edit *.xfdl files. The barriers I see at this preliminary point is to convert the xml to a readable image and then to make that editable where possible.

So, in this first part, we will do the very basic converting an *.xfdl file to an *.xml file. The code should be self explanatory but if there are questions, post them through comments and I’ll do my best at getting an answer to you.

""" IMPORTS """
from base64 import *
import gzip, os, sys

""" DEATH!!! """
# Standard way to die...
def die(msg=None):
    if msg == None:
        msg = "Unknown error."
    print " [*] ERROR - %s" % msg

# No file name, then we have nothing to do!
if len(sys.argv) < 2:
    die("Did not specifiy a file name.")

""" GET FILE """
# In a more advanced version, this will check the magic value of the file as well to
# ensure it is an *.xfdl file.
filename = sys.argv[1]
print "Using %s" % filename

# Nothing tough, grab the magic number (1st line) and then store the rest as a variable.
f = open(filename,'r').read()
magic = f.splitlines()[0]
print "magic: %s" % magic
data = f.split(magic)[1]
print "Got Data."
del f

""" BASE64 DECODE """
# First we decode the base64.
f = open('temp.gz','wb')
print "Base64 Decoded."

# Yes, I know this writing to a file and then deleting it is ugly but I have not found
# a way to gunzip from a data stream.
f ='temp.gz','rb')
gunzip_data =
print "Gunzipped Data."

# As this gets more advanced, it should be able to stay as a data stream for editing.
filename = filename.split(".")[0] + ".xml"
f = open(filename,'wb')
print "Saved to temporary file '%s'" % filename

Nothing too involved here, simply open the file, strip out the first line and the decode the rest from base64 and gunzip that data to get the xml inside.  In the next tutorial, we’ll look at the structure of that xml, once I actually understand it or find decent documentation on it!

64bit Flash for Linux

This has been a pain for a long time.  I went though and installed flash for Linux in this method but it only half worked for my 64bit distro in Ubuntu.  Too many problems coordinating with 32bit libraries and I would have flash applications that loaded fine but would not accept clicks, for example a video that I cannot pause or fast forward.  I set out to find a solution, as I realized this was a problem not with flash but with coordinating that flash with a 64bit distro.  For those interested, there is a 64 bit, Linux release and it’s installation is far more simple.  It is located on Adobe’s website, but hidden deep in some of the small text, definitely not a feature that stands out until you read through the page.  Here’s the solution:


function die {
	if [ "$1" == "" ]; then
		echo "[*] ERROR -- Not Specified."
		echo "[*] ERROR -- $1"
	exit 1

function check_root {
	if [ "`whoami`" != "root" ]; then
		die "You need root to install the 64bit Flash Player."

## Set root user
echo "You are root, the install will begin now."

## Download the package
echo "Downloading..."

## Untar the package
echo "Unpacking..."
tar xzvf

## Move the file
echo "Installing..."
cp -v /usr/lib/mozilla/plugins

## Clean Up
echo "Cleaning..."
rm -rf

## Done!
echo "Done!"
exit 0

VirtualBox – USB Devices

As a military member, I am issued a CAC card, which is a smart card carrying a PKI certificate for logging onto web interfaces and signing documents.  As  Linux user, I’ve been frustrated by the Windows specifics for utilizing CAC cards and have been happy to find alternatives through libcoolkey and pcsc_lite.  These work well with Firefox and I can log onto web interfaces just fine, but have not had a viable, Linux solution to signing documents.  In the military, we use an IBM product, PureEdge to utilize our forms which are *.xfdl documents.

The solution I have come to, although not purely Linux, allows me to sign documents without rebooting to another OS.  For testing purposes, I have had Windows XP running in VirtualBox so I decided to utilize that.  The problem came in that I was using virtualbox-ose and needed to not use the open source version for access to the USB devices.   The process then is relatively and well documented with simple Google searches:

  1. Set vboxuser in the user’s group.
  2. Configure your USB devices (in this case the CAC card reader) to be detected by the guest OS.
  3. Run the guest OS and install ActivClient 6.0 and Silinas ApproveIt to be able to sign *.xfdl documents.

See, simple… hmm, that sounds too close to Windows 7 add but I promise it is not!  I may be a PC but Windows 7 was NOT my idea!!

Linux bash script for wifi.

When starting with Backtrack4, I compiled and installed the Broadcom wl driver for my laptop’s wifi. The unfortunate thing was that I got very frustrated because the default connection manager, wicd was getting confused when I would go to a network other than the one I initially connected to after boot-up. Shortly after that, Ubuntu 9.10 was experiencing the same difficulty after upgrading the kernel. So to work around using a network manager, I created a quick script to use.

In this script, you can see that you can pass a variable for your network name and key in the same format as you would normally. This was a fun script as it could easily be adapted as it’s own network manager, even with a little more work, you could have it in the tray, it’s own gui, etc. It’s nothing more than the commands typically used to connect on wifi but it just automated the process. I then went and created a child script for my most used networks, and after placing these in my bin, I actually have started to prefer this method.

Here’s the script:


# die with honor
function usage() {
	echo "usage: ./connectWifi \"<essid>\" [key]"
	echo "       *key in ascii prefaces s:[key]"
	exit 1

# killed in disgrace
function die() {
	echo "   [*] ERROR: $1..."
	exit 1

# check for essid
if [[ $1 ]]; then
	# setup
	echo "Starting..."
	ifconfig eth1 down
	dhclient -r eth1 -q
	echo " -Previous connection dropped."
	ifconfig eth1 up
	iwconfig eth1 essid "$1"
	echo " -ESSID Set to $1."
	# check for key
	if [[ $2 ]]; then
		iwconfig eth1 key $2
		echo " -Key set to $2."
	# connect
	iwconfig eth1 mode Managed
	echo " -Connecting..."
	dhclient eth1
	# announce success
	if [[ $? -eq 0 ]]; then
		echo "Successfully connected to $1!"
		exit 0

	# no variables

# declare failure
die "Failed to connect to $1."

This can serve as a good example of both the commands in connecting to wifi and an introduction to bash scripting. Please comment on the code and offer any suggestions you may have!