GeoClue vs Geocode-Glib

This post has been superseded by a more recent post with updated information.  

GeoClue, used in Gnome and Unity, is a Dbus service that consolidates location input from multiple sources to estimate a best location. It's lightly maintained, and the most recent maintainer has essentially deprecated it in favor of his newer Geocode-Glib

That announcement is here, plus a bit of reading-between-the-lines and a few subsequent clarifications.

The big advantage if geocode-glib0, is that it uses GObject introspection instead of specialty DBus bindings. The big disadvantage is that it leaves KDE and other non-Gnome environments unsupported...and has less functionality that the older Geoclue.

For now, it looks like I need to stick with GeoClue, and perhaps even help maintain it for my current weather-backend project. geocode-glib simply doesn't do the job I need GeoClue to do.

---

Here is an example of using python and geocode-glib to get geolocation information. I have not seen any examples of geocode-glib anywhere else, so I may be first here to use the lib with python:

#!/usr/bin/env python3
import gi.repository
from gi.repository import GeocodeGlib

# Create an object and add location information to it 
location = GeocodeGlib.Object()
location.add('city','Milwaukee')

# Do the gelocation and print the response dict
result = location.resolve()
[print(item[0], item[1]) for item in result.items()]

Give it a try...
The relevant packages are libgeocode-glib0 and gir1.2-geocodeglib-1.0
The Geocode-Glib source code and API reference are hosted at Gnome.

Add NTP to the router/gateway

This post is obsolete and has been superseded

NTP is useful to set the time of LAN devices. In addition, the 'adjtimex' package updates the hardware clock. (Slightly out-of-date instructions)

1. Install NTP with the following command:
   

   apt-get install ntp adjtimex

2. Edit the /etc/ntp.conf file to broadcast time to the LAN:
   

   ## Around Line 48
   # If you want to provide time to your local subnet, change the next line.
   # (Again, the address is an example only.)
   #broadcast 192.168.123.255
   broadcast 192.168.1.0

3. Edit /etc/hosts.allow and /etc/hosts.deny to limit access to ntpd. Edit /etc/hosts.allow to look more like this:
   

   sshd:              192.168.1.0/26
   debtorrent-client: 192.168.1.0/26
   ntpd:              192.168.1.0/26
   ALL:               192.168.1.0/26
   # /26 creates the range .1.0 - .1.62
   

   And edit /etc/hosts.deny to look more like this:
   

   sshd:              ALL
   debtorrent-client: ALL
   ntpd:              ALL
   ALL:               ALL
   

4. xinted and dnsmasq do not interact with ntpd, and no changes are required.
5. Firewall rules to open those two listening ports. Edit the file /etc/network/if-up.d/00-firewall to add the following rules:
   

   # ALLOW INCOMING OPEN PORTS TO THE SERVER FROM OUTSIDE HERE
   #
   # Allow incoming debtorrent requests on TCP ports 9899-9990
   iptables -A INPUT -p tcp --dport 9899 -j ACCEPT
   iptables -A INPUT -p tcp --dport 9900 -j ACCEPT
   #
   # Allow NTP syncs on UDP port 123
   iptables -A INPUT -p udp --dport 123 -j ACCEPT 
   iptables -A OUTPUT -p udp --sport 123 -j ACCEPT
   #
   #
   

6. Restart ntpd with these commands:
   

   sh /etc/network/if-up.d/00-firewall  # Reload the firewall
   service ntpd restart                 # Reload /etc/ntp.conf
   

Installing a Sangoma S518 DSL Modem card in a Dell Optiplex GX60 running Debian 6

This post is obsolete and has been superseded

Ebay provided a new-to-me used DSL PCI modem card to replace my 10-year-old DSL modem. The old modem still works; this is purely for fun.

The card is recognized, but no kernel module is associated with it.

lspci -vv
01:07.0 Network controller: Globespan Semiconductor Inc. Pulsar [PCI ADSL Card] (rev 01)
 Subsystem: Globespan Semiconductor Inc. Device d018
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping+ SERR+ FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=slow >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 64 (750ns min, 50000ns max)
 Interrupt: pin A routed to IRQ 16
 Region 0: Memory at ff8f0000 (32-bit, non-prefetchable) [size=64K]
 Capabilities: [40] Power Management version 2
  Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
  Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-

Sangoma has a Linux driver, but it needs to be compiled, so it needs linux source code to refer to during compilation. The linux kernel itself does not need to be recompiled. It's annoying and time consuming, but it does work. Sangoma's information and downloads are at their wiki. Details of how to prepare the kernel source and headers is here.

Compatibility with networking and commands:

• Do not make any changes to the /etc/network/interfaces file. The wanrouter program defines and brings up/down the dsl interface without using the file.
• Ifup/ifdown does not work, because they rely on the interfaces file.
• Ifconfig *does* work but only after a wanpipe is already active. Ifconfig up/down do work without restarting the wanpipe.

The nomenclature and order of events can be confusing:

wanrouter is the command that starts everything. It's just a bash script at usr/sbin/wanrouter. Don't be fooled by the name - it's not really a router. The wanrouter command turns on/off a wanpipe. A wanpipe is the low-level connection to the PCI card, and they create/destroy the dsl0 high-level network interface. Wanpipes are configured by the wancfg command.

pon/poff create a pppoe connection from the dsl0 interface to the upstream network provider. The pppoe connection, including dsl login/password, are configured by the pppoeconf command. pon/poff are actually just part of pppd, the ppp daemon, which creates another high-level interface, ppp0 to represent the actual live dsl link.

The upshot of all this is that wanrouter must create the dsl0 interface before pon can create the ppp0 connection (interface), and poff must terminate the ppp0 interface before wanrouter can destroy the dsl0 interface. Happily, wanpipes include a place to insert these commands so wanrouter appears to handle it all.

How to install the Sangoma wanpipe drivers, configure the card, configure the interface, and configure pppoe. The dsl line does not need to be plugged in until the final steps of configuring pppoe.

# Install the tools needed
apt-get install build-essential linux-source-2.6.32 linux-headers-2.6.32-5-686 libncurses5-dev bison libtool pppoe

# Get the Sangoma Wanpipe package. Unpack the linux-source and wanpipe packages 
cd /usr/src
wget ftp://ftp.sangoma.com/linux/current_wanpipe/wanpipe-3.5.18.tgz
tar zxvf wanpipe-3.5.18.tgz
tar xjf /usr/src/linux-source-2.6.32.tar.bz2

# Prepare the linux source for the wanpipe install script 
cd linux-source-2.6.32
cp /usr/src/linux-headers-2.6.32-5-686/Module.symvers ./
make oldconfig && make prepare && make modules_prepare

# Run the wanpipe install script
cd /usr/src/wanpipe-3.5.18
./Setup install

The script will ask for the linux source directory: /usr/src/linux-source-2.6.32. It will throw a lot of questions about using 2.6.32-5-686 instead, just answer yes and let the installer continue.

# When install is successfully completed
cd /home/USERNAME
wanrouter hwprobe  # Test if the card is detected
wancfg             # Ncurses tool to configure the wanpipe and interface

See the Sangoma Wiki for details, really all you need to choose is the interface name (for example, 'dsl0')

wanrouter start wanpipe1   # Test - should bring up interface
ifconfig                   # The interface should be on the list
ifconfig dsl0 down         # Test - should bring down interface
ifconfig                   # The interface should *not* be on the list
ifconfig dsl0 up           # Test - should bring up interface
ifconfig                   # The interface should be on the list
wanrouter stop wanpipe1    # Test - should being down interface
ifconfig                   # The interface should *not* be on the list

Plug in the dsl connection in order to configure pppoe. Then run the PPPoE configuration program (pppoeconf). You need your dsl login and password at this point.

ppoeconf

The pppoeconf program will ask two important questions:

• Do you want to start PPPoE at each startup? NO, because it will fail - dsl0 will not be ready yet
• Do you want to start PPPoE now? You can, but if there are any problems, the process will be orphaned. Kill it with the command 'poff -a'

You can see the PPPoE configuration (linking it to the dsl0 interface) in /etc/ppp/peers/dsl-provider. You can see your dsl username and password in /etc/ppp/pap-secrets.

To manually open/close the dsl connection:

wanrouter start     # To bring up the dsl0 interface. Doing this at boot is part of the Wanrouter install
pon dsl-provider    # To bring up the ppp0 interface, which is the real PPPoE connection 
                    # (with an IP address). We'll automate this in the next section
plog                # A handy debugging tool. Take a quick look at the log
ifconfig            # The dsl0 interface does not have an IP, and the new ppp0 interface does have an IP
poff                # To close the PPPoE connection, and bring down the ppp0 interface
wanrouter stop      # To bring down the dsl0 interface. Doing this at shutdown is part of the Wanrouter install

To automatically open/close the dsl connection: Go back into wancfg. Edit the wanpipe1 file --> Interface Setup --> Interface Configuration --> Advanced options. Insert a start script and a stop script as follows:

pon dsl-provider    # Append this to the bottom of the START script

poff -a             # Append this to the bottom of the STOP script

Save the wanpipe1 config file, and let's test automatic dsl connection/disconnection:

wanrouter stop      # In case it was on.
ifconfig            # Neither dsl0 nor ppp0 interfaces should be live.
wanrouter start     # Bring up dsl0. The script should then bring up ppp0
ifconfig            # ppp0 should be up, and have an IP address. If not, try again - ppp0 is often missing the first time I try.
wanrouter stop      # Bring down the intefaces
ifconfig            # Should be back to the normal down state. ppp0 and dsl0 should not be showing.

Finally, test with a reboot and a shutdown to see in the interfaces change properly. Success! Time to clean up using the following commands:

apt-get remove build-essential linux-source-2.6.32 linux-headers-2.6.32-5-686 libncurses5-dev bison libtool
apt-get autoremove
rm -r /usr/src/wanpipe-3.5.18
rm -r /usr/src/linux-source-2.6.32

BUG: missing LSB tags and overrides. When I tried to install something else later, I got the following warnings:

insserv: warning: script 'K01wanrouter' missing LSB tags and overrides
insserv: warning: script 'wanrouter' missing LSB tags and overrides

A quick search on the warnings gave an answer. LSB tags are used by init, and the tags are easily added to the beginning of the /etc/init.d/wanrouter script. Here is a sample script that eliminated the warning:

#! /bin/sh        # Just to show where we are in the file

### BEGIN INIT INFO
# Provides:             wanpipe
# Required-Start:       $syslog
# Required-Stop:        $syslog
# Default-Start:        2 3 4 5
# Default-Stop:         
# Short-Description:    kernal support to DSL modem
### END INIT INFO

Final notes:

• Three elements of the Sangoma package failed to compile: LibSangoma API library, LibStelephony API library, and API Development Utilities. I have seen no effect from those failures.
• To uninstall WANPIPE package run ./Setup remove
• There is additional documentation at /usr/share/doc/wanpipe
• A firmware update utility is included in /etc/wanpipe/util
• 'wanpipemon' is an included diagnostic tool. The easiest way to use it is 'wanpipemon -g' for the ncurses gui.
• Changing the default route to send packets across the dsl connection is beyond the scope of what I wanted to do. I just wanted to see if it worked.

Using a US DOD CAC Card with Ubuntu 9.10

Superseded by http://cheesehead-techblog.blogspot.com/2015/10/cac-on-firefox-using-ubuntu-1504.html

Adding a CAC Card reader and using a CAC card with Ubuntu used to be bloody hard. Getting the hardware recognized, getting the add-ons to Firefox and Evolution, installing the certificates, what a pain!
Well, I tried agin, using the Ubuntu help center instructions at https://help.ubuntu.com/community/CommonAccessCard
Result: I can log into AKO using my CAC Card! After four years of hoping. Hooray!

Xubuntu desktop wallpaper from a website (NOAA Radar)

This post has been superseded by a newer post. Much of this information is still valid, but the newer post has more detail amd examples, and includes more services.

---

Living in the midwest, I check the weather radar a lot to protect my laundry drying outside from lots of pesky thunderstorms. So I want to make the radar image my desktop picture in Xubuntu, and to have it automatically update.

To get the image: I'm using http://radar.weather.gov/lite/N0R/MKX_0.png. It is from the United States National Weather Service and updates every 5-6 minutes.

A shell script to refresh the radar image as the desktop picture:

#!/bin/sh
# BEGIN CONFIGURATION
# This is the path of the final output files that get read by other processes.
# Working files show up here, too. You may wish to create your own directory.
Local_Path=/home/me/.config/weather/
Local_Name="${Local_Path}radar_image.png"
Username=<your username>

# This is the closest weather station for observations. Find your weather 
# station: http://www.nws.noaa.gov/xml/current_obs/. Format is four letters. 
# All UPPER CASE. For example, 'KMKE' for Mitchell Field in Milwaukee, WI
Station=KMKE

# This is the closest weather radar. Find your radar: http://radar.weather.gov/
# Check the link to your weather radar, for example:
# http://radar.weather.gov/ridge/radar.php?rid=mkx&product=N0R&overlay=11101111&loop=no
# The radar name is in the 'rid=' field. In this example, mkx is Milwaukee, WI
# Format is UPPER CASE. For example, 'MKX' for Milwaukee.
Radar_Name=MKX
Radar_Url="http://radar.weather.gov/lite/N0R/${Radar_Name}_0.png"

# (OPTIONAL) The height of your top menu bar, in pixels.
# The radar image is padded by this amount on the top edge so the menu doesn't
# block the timestamp in the image.
#Radar_Image_Top_Padding=15
# END CONFIGURATION

# BEGIN RADAR IMAGE
# Download the radar image.
echo "Weather Update: Downloading the most recent radar image available..."
curl -o $Local_Name $Radar_Url

# (OPTIONAL) Use imagemagick to pad the image top so the timestamp is not 
# blocked by the menu bar.
#convert $Local_Name -background none -splice 0x${Radar_Image_Top_Padding} $Local_Name

# Refresh desktop background with 'xfdesktop -reload'. NOTE - some versions 
# of XFCE flicker all the icons brighter when this occurs, providing visual 
# feedback that the refresh occurred. An Alternate method to avoid the 
# flicker is below.
# The 'DISPLAY=:0.0' prefix is required so root processes like cron and 
# Upstart can process it.
# The 'sudo -u $Username' is required because a root process (like an Upstart 
# trigger) may be trying to change a user's desktop. Sudo changes the command 
# to run as user instead of root. Use your username, of course.
DISPLAY=:0.0 sudo -u $Username xfconf-query -v -c xfce4-desktop -p /backdrop/screen0/monitor0/image-path -s $Local_Name
DISPLAY=:0.0 sudo -u $Username xfdesktop -reload

# Alternate method to avoid the flicker by changing desktop pictures for 
# just a moment, then changing it back.
#DISPLAY=:0.0 sudo -u $Username xfconf-query -v -c xfce4-desktop -p /backdrop/screen0/monitor0/image-path -s /usr/share/xfce4/backdrops/xfce4logo.png
#DISPLAY=:0.0 sudo -u $Username xfconf-query -v -c xfce4-desktop -p /backdrop/screen0/monitor0/image-path -s $Local_Name

# END RADAR IMAGE

I'll save this script as radar_background.sh, and make it executable with sudo chmod +x radar_background.sh.

Notes:

1. The DISPLAY=:0.0 element is explained here.
2. The xfconf-query command, and how to change the background using DBus, are discussed in the XFCE forums

Updating the desktop picture manually:

Since we have it in a shell script already, we can create a .bashrc alias to run the script manually.
nano .bashrc opens the .bashrc for editing.
Add the line alias radar='/home/me/radar_background.sh' to the bottom of the file and save it.
Open a new terminal window (terminals only read the .bashrc upon starting) and try the command radar.



Updating the desktop picture automatically: Since we can update the desktop image using bash commands, let's make a crontab entry to update the desktop image automatically. Here's what it looks like - a crontab entry with just the shell command:

# m h  dom mon dow   command
*/20 * * * * /home/me/radar_background.sh

Note that the desktop picture will refresh every 20 minutes.

Explaining the cron instructions:

# m h dom mon dow command - That's just part of the crontab

*/20 * * * * - tells the machine to run the script every 20 minutes. */5 * * * * will run the script every five minutes.

> /dev/null at the end (optional) - tells the machine to not e-mail me every time the script runs.

Make sure the command is all on one line (not wrapped), or you'll get crontab errors.

Using DBus on Xubuntu 8.04

This post is obsolete has been superseded by my 2012 dbus tutorial series.

DBus is a system that permits different applications to exchange information. Tutorial Reference Other Reference.
Sometimes, DBus crashes upon restart from a suspend or hibernation. These bash commands will help you figure out if it has crashed, and how to restart it.

$ps -e | grep `cat /var/run/dbus/pid` # Confirm if DBus is running by checking for the PID number in the list of live processes.
                                      # If DBus is running, this will return the process number. 
                                      # If not, it will return nothing.
$sudo rm /var/run/dbus/pid            # Remove the stale pid file so DBus can be restarted.
$sudo dbus-daemon                     # Start DBus again.

A python script uses DBus to see if the network connection is available by asking Network Manager:

#! /usr/bin/env python
import dbus
bus = dbus.SystemBus()
item = 'org.freedesktop.NetworkManager'
eth0_path = '/org/freedesktop/NetworkManager/Devices/eth0'
eth1_path = '/org/freedesktop/NetworkManager/Devices/eth1'
interface = 'org.freedesktop.NetworkManager.Devices'

# There are two possible network interfaces: eth0 (wired) and eth1 (wireless).
eth0 = dbus.Interface(bus.get_object(item, eth0_path), interface)
if eth0.getLinkActive(): print('The wired network is up') # getLinkActive() is a boolean, TRUE if the network link is active
eth1 = dbus.Interface(bus.get_object(item, eth1_path), interface)
if eth1.getLinkActive(): print('The wireless network is up')

This shell script does exactly the same thing, using the same DBus call:

# This shell script checks Network Manager if the network is up, using dbus as the communications medium.
# There are two possible network interfaces: eth0 (wired) and eth1 (wireless). Of course, you may need to alter these to meet your own circumstances.
# The basic format of dbus-send is: dbus-send --system --dest=org.freedesktop.NetworkManager /org/freedesktop/NetworkManager/Devices/eth0 --print-reply org.freedesktop.NetworkManager.Devices.eth0.getLinkActive
DEST='org.freedesktop.NetworkManager'
PPATH='/org/freedesktop/NetworkManager/Devices'
DEVICE='org.freedesktop.NetworkManager.Devices'

result_eth0=`dbus-send --system --dest=$DEST $PPATH'/eth0' --print-reply $DEVICE'.eth0.getLinkActive'`
shaved_eth0=`echo $result_eth0 | cut -d ' ' -f8`
if [ $shaved_eth0 = 'true' ]; then echo 'The wired network is up'; fi

result_eth1=`dbus-send --system --dest=$DEST $PPATH'/eth1' --print-reply $DEVICE'.eth1.getLinkActive'`
shaved_eth1=`echo $result_eth1 | cut -d ' ' -f8`
if [ $shaved_eth1 = 'true' ]; then echo 'The wireless network is up'; fi

A Python script that queries Network Manager to get the list of wireless networks.

import dbus
item = 'org.freedesktop.NetworkManager'
path = '/org/freedesktop/NetworkManager'
interface = item + '.Device'

network_list = []
bus = dbus.SystemBus()

# Create a Network Manager interface and get the list of network devices
event = dbus.Interface(bus.get_object(item, path), interface)

# Create an interface for each device
# Query each interface to see if it's wireless
# Query each wireless interface for the networks it sees
for device in event.getDevices():
    device_interface = dbus.Interface(bus.get_object(item, device), interface)
    if device_interface.getType() == 2:  # 0 unknown, 1 wired, 2 wireless
        network_list.extend(device_interface.getNetworks())

# Reformat the network names in the list to be more readable
if network_list:
    for entry in network_list:
        #print entry    # String of path/to/network_name
        entry_list = entry.split('/')
        print entry_list[-1]  # String of network_name

A Python listener that catches the changes in wireless signal strength using both available methods.

import dbus, gobject
from dbus.mainloop.glib import DBusGMainLoop

def print_device_strength1(*args):  #Use the received signals
    signal_strength = args[1]
    print ('Signal Strength (Method 1): ' + str(signal_strength) + '%')

def print_device_strength2(*args, **kwargs):  #Use the received signals
    signal_strength = args[1]
    print ('Signal Strength (Method 2): ' + str(signal_strength) + '%')

DBusGMainLoop(set_as_default=True)    # Set up the event loop before connecting to the bus
bus_object = dbus.SystemBus()

# The variables you need. I used the shell command 'dbus-monitor --system' to find this information
sender = 'org.freedesktop.NetworkManager'
path = '/org/freedesktop/NetworkManager'
interface = sender
member = 'DeviceStrengthChanged'

# Method 1 - bus_object.proxy_object.connect_to_signal(method, action, filter, message_parts)
proxy_object = bus_object.get_object(sender, path)
proxy_object.connect_to_signal(member, print_device_strength1, dbus_interface = interface)

# Method 2 - bus_object.add_signal_receiver(action, [filters])
bus_object.add_signal_receiver(print_device_strength2, dbus_interface = interface, member_keyword = member)

# Start the loop
loop = gobject.MainLoop()
loop.run()

Thunar responds beautifully to D-Bus. Introspection is fully set up, so it's easy to use with the d-feet application. Useful for launching programs, opening folders and windows, and manipulating the trash. Launching a program by this method means that the the window manager launches the program, not the script or terminal, so the program can remain open after the script or terminal terminates.

#!/usr/bin/env python
import dbus
item = ('org.xfce.Thunar')
path = ('/org/xfce/FileManager')
interface = ('org.xfce.FileManager')
event = dbus.Interface(dbus.SessionBus().get_object(item, path), interface)

# These three lines at the end of the script open the file's 'properties' window
display = (':0')         # The current session screen
uri = ('/home/me/dbus_test.py')
event.DisplayFileProperties(uri, display)

# These three lines at the end of the script launch a new application
display = (':0')         # The current session screen
uri = ('/usr/bin/gftp-gtk')
event.Launch(uri, display)

# These four lines at the end of the script open a folder window and optionally select a file
display = (':0')         # The current session screen
uri = ('/home/me/.cron')
filename = ('anacrontab.daily')
event.DisplayFolderAndSelect(uri, filename, display)

A sample hal script.

#!/usr/bin/python
"""This python 2.5 script uses dbus to check if the lid switch is open.
Based on an original python script at http://schurger.org/wordpress/?p=49"""
import dbus

dest = 'org.freedesktop.Hal'
hal_path = '/org/freedesktop/Hal/Manager'
hal_interface = 'org.freedesktop.Hal.Manager'
udi_interface = 'org.freedesktop.Hal.Device'

# Get the list of possible input switches. The return is a list of paths.
bus = dbus.SystemBus()
hal = dbus.Interface(bus.get_object(dest, hal_path), hal_interface)
list_of_udi_paths = hal.FindDeviceByCapability('input.switch')

# Filter the list for the word 'lid'. Print the status for each one.
for udi_path in list_of_udi_paths:
    udi = dbus.Interface(bus.get_object(dest, udi_path), udi_interface)
    if udi.GetProperty('button.type') == "lid":
        # The button.state.value is FALSE if the lid is open.
        if udi.GetProperty('button.state.value'): print ('Lid is closed')
        else: print ('Lid is open') 
    else: print ('Problem: I could not find the lid switch. Sorry.')

Notes:

• The D-feet application is very handy for exploring DBus, and figuring out how to communicate with it. It's available in the Ubuntu repositories.
• More information on the destination/path/interface settings is available from each application's XML config files, found in the /etc/dbus-1/system.d and /session.d directories.
• The system-tools-backends DBus interfaces look promising, with methods for network interfaces, time, users and groups, and more. But I couldn't get any of it to work. One hint suggested that the DBus message must be sent by root instead of user.
• xfce4-terminal has a Launch method, seemingly for launching items in the terminal (source code). I can see how that would be handy, but I couldn't get it to work.

You Are Here on a Google Map

This post is obsolete and has been superseded

The following python 2.x script shows your current (GPS-enabled) location on a Google Map. A useful learning experience:

#!/usr/bin/env python

"""This is a python 2.5 script that plot's a GPS receiver's location on the
Google Maps website.

In order to work, you need a network connection, an attached GPS receiver, and
the GPS daemon (gpsd).
"""
import os
#import subprocess and SU
import gps
import dbus
import sys


def test( ):
    """ Step 1: Test for the existence of a running gpsd, test for the existence of an open network connection, and test for a firefox process.
    If any fail, give an error message, don't try to recover. FUTURE: Could also use DBus to test for firefox and gpsd."""

    process_list = os.popen('ps -e')    # os.popen is deprecated in favort of subprocess.Popen
    #process_list = SU.Popen(['ps','e'], stdout=SU.PIPE).stdout.read()  
    gpsd_existence_flag = 0
    firefox_existence_flag = 0
    for line in process_list.readlines():
        if line.count('gpsd') > 0: gpsd_existence_flag = 1
        if line.count('firefox') > 0: firefox_existence_flag = 1

    if not gpsd_existence_flag:
        print ("gpsd is not running. Use 'gpsd -b /dev/ttyUSB0' to start it, and then try again.")
        sys.exit()       
    else: print ('Checking...found gpsd')

    if not firefox_existence_flag:
        print ("firefox is not running. Please start it and try again.")
        sys.exit()
    else: print ('Checking...found firefox')

    bus = dbus.SystemBus()
    nm_item = ('org.freedesktop.NetworkManager')  # This string gets used a lot
    nm_path = ('/org/freedesktop/NetworkManager')
    nm_device = ('org.freedesktop.NetworkManager.Device')

    list_of_interface_paths = dbus.Interface(bus.get_object(nm_item, nm_path), nm_device).getDevices()

    found_network_flag = 0
    for interface_path in list_of_interface_paths:
        one_interface = dbus.Interface(bus.get_object(nm_item, interface_path), nm_device)
        if one_interface.getLinkActive():   # True if there is an active network on this interface
            if one_interface.getType() == 2: # 0 unknown, 1 wired, 2 wireless
                print('Checking...found the wireless network') 
                found_network_flag = 1
            elif one_interface.getType() == 1: 
                print('Checking...found the wired network')
                found_network_flag = 1
                
    if found_network_flag: return
    else:
        print ("cannot find a network connection. Please connect and try again.")
        sys.exit()    


def get_position_fix( ):
    """Step 2: Get a position fix from gpsd."""
    session = gps.gps('localhost','2947')  # Open a connection to gpsd
    session.query('p')                     # Get the location fix 
    lat = session.fix.latitude
    lon = session.fix.longitude
    print ('Location is ' + str(lat) + ' latitude and ' + str(lon) + ' longitude.')
    return (lat, lon)


def show_map(lat_lon_tuple):
    """Step 3: Submit the position fix to Google Maps. Note that the parentheses '()' in the URL must be escaped '\' to work.
    Sample URL format: http://maps.google.com/maps?q=37.771008,+-122.41175+(You+can+insert+your+text+here)&iwloc=A&hl=en"""
    url_string = ('http://maps.google.com/maps?q=' + str(lat_lon_tuple[0]) + ',+' + str(lat_lon_tuple[1]) + '+\(You+Are+Here\)&iwloc=A&hl=en')
    os.popen('firefox ' + url_string)
    return

# Run this script as a standalone program
if __name__ == "__main__" :
    test()
    location = get_position_fix()
    show_map(location)

GPS and Xubuntu 8.04

This post is obsolete and has been superseded

I'm experimenting with USB GPS receiver (dongle). It's a Canmore GT-730F that I received in January 2009. Here's what I've learned so far.

Manually getting data using the command line (source):

1. Check dmesg, the kernel log, to find out where the device has been mounted. In my case, it mounts reliably to /dev/ttyUSB0. If it doesn't mount, try the command sudo modprobe pl2303 to load the correct USB driver.
2. Set the data output rate to 4800 baud using the stty command: stty 4800 > /dev/ttyUSB0
3. Read the data stream using the cat command: cat /dev/ttyUSB0
4. You should see a set of data scroll down the screen. Use CTRL+C to end the test.

The Linux GPS Daemon (gpsd) is the central clearinghouse for receiving GPS data from the receiver, buffering it, and forwarding it to the applications that want it. gpsd has features to broadcast to dbus (system bus), update ntpd, and respond to a multitude of specific queries from clients. References: Project home page, gpsd man page, and a great example program

$sudo apt-get install gpsd gpsd-clients  # Installs the daemon (gpsd) and test set (gpsd-clients) packages
$gpsd -b /dev/ttyUSB0                    # Start gpsd, telling it where to find the receiver
$cgps                                    # Current satellite data - great way to test that the receiver and gpsd are working

gpsfake is a gpsd simulator. It tricks gpsd into reading from a logfile instead of a real GPS device. Very handy for testing without actually using a GPS dongle. It is included with the gpsd package, and has a man page for additional reference. To make a logfile, and then to use gpsfake:

$cat /dev/ttyUSB0 > path/to/testlog  # Create the log file. Use CTRL+C to end the capture.
$gpsfake path/to/testlog             # Run gpsd simulator (not a daemon - it will occupy the terminal)

Python interface to gpsd (python-gps) is a programming tool to build your own gps-aware application.

>>>import gps                             # Load the module
>>>session = gps.gps('localhost','2947')  # Open a connection to gpsd
>>>session.query('o')                     # See man gpsd(8) for the list of commands
>>>print session.fix.latitude             # Query responses are attributes of the session
>>>dir(session)                           # To see the possible responses
>>>del session                            # Close the connection to gpsd

In this case, it seems that I need a periodic session.query('p'), which just gives lat/lon and timestamp.

Time might be an issue, since the system and the GPS may think the time is different. To see if it's an issue, compare them using the python script below. In my tests, they vary from 0.08 to 1.3 seconds apart, not enough to worry about. GPS timestamps use GMT, not localtime.

#!/usr/bin/env python
import calendar, time, gps
system_time = calendar.timegm(time.gmtime())  # System time (in seconds)
session = gps.gps('localhost','2947')         # Open a connection to gpsd
session.query('p')                            # See man gpsd(8) for the list of commands
gps_time = session.timings.c_recv_time        # GPS time (in seconds)
print ('The time difference is ' + str(system_time - gps_time) + ' seconds.')

MGRS (military map coordinates) conversion to/from latitude and longitude is not currently available in Ubuntu...that I can find. The dongle documentation doesn't mention MGRS at all. An online converter is available. The proj package looks promising, but I haven't figured it out yet. Perhaps Lat/Lon -> UTM -> MGRS?

DBus access appears to be undocumented...but there are tantalizing hints on Google that examples are out there. I can listen to dBus using cgps to make traffic, then dbus-monitor --system to see it.

The best storage format for tracklogs, routes, and waypoints seems to be GPX format, since it's easy to understand and cgpxlogger, included with gpsd, will create an XML track in GPX 1.1 format. Google's KML is more powerful, but also much more complex. GPSbabel universal data translator is a command-line application that translates one file type to another, and does convert GPX <-> KML.

$cgpxlogger -i 30 > path/to/logfile         # Save data every 30 seconds to an XML file
$gpsbabel -i gpx -f path/to/gpx_file -x duplicate -o kml -F path/to/kml_file
$#gpsbabel [options] -i INTYPE -f INFILE -x FILTER -o OUTTYPE -F OUTFILE

GPSdrive navigation system looks cool, but I couldn't get maps to load, so it's utility was limited. However, it seems that online plotting of tracklogs, routes, and waypoints is possible on Google Maps (and Yahoo Maps, and others). One example is the cool GPS Visualizer.

Gypsy is an alternative daemon, but not currently in Debian or Ubuntu, so I haven't tried it. Last release 0.6 in March 2008.

GPSman device manager is an app I know nothing about. I couldn't get it to work, so I removed it. The dongle seems small enough and simple enough that it may not need to be 'managed' at all.

Installing DOD CLASS 3 CA-7 security certificate into Firefox 3.0

Superseded by http://cheesehead-techblog.blogspot.com/2015/10/cac-on-firefox-using-ubuntu-1504.html

The US Army has a plethora of websites to keep it's mighty bureaucracy chugging along. Unfortunately, the security certificate they all require is not included in Firefox 3.0 (under Ubuntu 8.04). Here's how to get it and install it.
NOTE: The certificate is worthless to non-DOD people. It doesn't give you access, you still need an account. It's really boring, anyway, and none of the cool secret stuff is in these websites. All the certificate really does for most people is prevent the annoying message: This website has a certificate that I don't trust.

1. Download the following three files to the desktop:
   
   • http://dodpki.c3pki.chamb.disa.mil/rel3_dodroot_1024.p7b
   • http://dodpki.c3pki.chamb.disa.mil/rel3_dodroot_2048.p7b
   • http://dodpki.c3pki.chamb.disa.mil/dodeca.p7b
   
   
   The easy way in linux is to use curl -O http://dodpki.c3pki.chamb.disa.mil/rel_dodroot_1024.p7b -O http://dodpki.c3pki.chamb.disa.mil/rel3_dodroot_1024.p7b -O http://dodpki.c3pki.chamb.disa.mil/dodeca.p7b
   


2. Go to the Firefox Certificate Manager
   
   • Open Firefox
   • Edit Menu --> Preferences
   • Advanced settings
   • Encryption tab
   • View Certificates button


3. Import the three new certificates
   (Repeat for each certificate)
   
   • Authorities tab
   • Click the 'Import' button
   • Show firefox where the downloaded certificate is and click 'OK'


4. Fix a bug with the CLASS 3 CA-7 Certificate
   
   • In the Certificate Manager, Authorities Tab, scroll down to the new 'US Government' entries
   • Select DOD CLASS 3 CA-7, and click the 'Edit' button
   • Two of the certificate boxes should be checked. Check them if they are not:
     
     This certificate can identify web sites

This certificate can identify mail users


5. Whew. You're done. Close the windows, restart Firefox and test it.

Importing the same certificates to Evolution is a similar method.