Posts Tagged ‘ubuntu’

Setting up XMPP BOSH server

June 17, 2010 2 comments

This tutorial explains how to setup/troubleshoot XMPP server with BOSH. I’m not getting into what is XMPP and what is it good for. The first two paragraphs are theoretical. XMPP is stateful protocol in a client-server model. If web application needs to work with XMPP a few problems arise. Modern browsers don’t support XMPP natively, so all XMPP traffic must be handled by program running inside the browser (JavaScript/Flash etc…). The first problem is that HTTP is a stateless protocol, meaning each HTTP request isn’t related with any other request. However this problem can be addressed by applicative means for example by using cookies/post data.

The second problem is the unidirectional nature of HTTP: only the client sends requests and the server can only respond. The server’s inability to push data makes it unnatural to implement XMPP over HTTP. The problem is eliminated if client program can make direct TCP requests (thus eliminating the need of HTTP). However, if we want to address the problem within HTTP domain (for example because Javascript can only forge HTTP requests) there are two possible solutions, both require “middleware” to bridge between HTTP and XMPP. The solutions are “polling” (repeatedly sending HTTP requests asking “is there new data for me”) and “long polling”, aka BOSH. The idea behind BOSH is exploitation of the fact that the server doesn’t have to respond as soon as he gets request. The response is delayed until the server has data for the client and then it is sent as response. As soon as the client gets it he makes a new request (even if he has nothing to send) and so forth.

BOSH is much more efficient, from server load’s point of view and traffic-wise. In this tutorial I set up Openfire XMPP server (which also provides the BOSH functionality) with JSJaC library as client, using Apache as web server on Ubuntu 10.04. Openfire has Debian package and as such, installation is fairly easy. Just download the package and install. After installation browse to port 9090 on the machine it was installed on, and from there it’s web-driven easy setup. If you choose to use MySQL as Openfire’s DB make sure to create dedicated database before (mysqladmin create).

After initial setup, I wasn’t able to login with the “admin” user. This post solved my problem, openfire.xml is located at /etc/openfire (if you installed from package), you will need root privileges to edit it and then restart Openfire (sudo /etc/init.d/openfire restart). Other than that everything worked fine. Openfire server (as well as all major XMPP servers) provides the BOSH functionality, aka “HTTP Binding” aka “Connection Manager”. By default it listens on port 7070, with “/http-bind/” (the trailing slash is important).

To make sure it works (this is the part I couldn’t find anywhere, that’s why it took me long time to resolve all problems) I used “curl”, very handy tool (sudo apt-get install curl). To test the “BOSH server”:
# curl -d “<body rid=’123456′ xmlns:xmpp=’urn:xmpp:xbosh’ />” http://localhost:7070/http-bind/

Switch “localhost” with your server name, notice the trailing slash. Expected result should look like:

<body xmlns="" xmlns:stream="" authid="2b10da3b" sid="2b10da3b" secure="true" requests="2" inactivity="30" polling="5" wait="60"><stream:features><mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><mechanism>DIGEST-MD5</mechanism><mechanism>PLAIN</mechanism><mechanism>ANONYMOUS</mechanism><mechanism>CRAM-MD5</mechanism></mechanisms><compression xmlns=""><method>zlib</method></compression><bind xmlns="urn:ietf:params:xml:ns:xmpp-bind"/><session xmlns="urn:ietf:params:xml:ns:xmpp-session"/></stream:features></body>

Once verified, we can continue with the next step. Since the client is Javascript based, all Javascript restrictions enforced by the browser applies. One of these restrictions is “same origin policy“. It means that Javascript can only send HTTP requests to the domain (and port) it was loaded from and since it is served on HTTP (port 80) it can’t make requests to port 7070. Solution: Javascript client will make requests to the same domain and port. The requests will be forwarded locally to port 7070 by Apache. I guess you can use the same method to forward even to a different server but I didn’t try. I configured forwarding following this post but there is probably more than one way to do it.

Add to /etc/apache2/httpd.conf the following lines (root privileges needed):
LoadModule proxy_module /usr/lib/apache2/modules/
LoadModule proxy_http_module /usr/lib/apache2/modules/

Then, add to /etc/apache2/apache2.conf the following lines (root privileges needed):
ProxyRequests Off
ProxyPass /http-bind http://localhost:7070/http-bind/
ProxyPassReverse /http-bind http://localhost:7070/http-bind/
ProxyPass /http-binds http://localhost:7443/http-bind/
ProxyPassReverse /http-binds http://localhost:7443/http-bind/

Now restart the Apache (sudo /etc/init.d/apache2 restart) and make sure it starts properly. To verify the forwarding works, use the same curl method, this time as request to the Apache:
# curl -d “<body rid=’123456′ xmlns:xmpp=’urn:xmpp:xbosh’ />” http://localhost/http-bind

The result should be the same as before. If it doesn’t work there is problem with the forwarding. Once it is working, server side is ready. On the client (in my case JSJaC), you should specify to use BOSH/HTTP Bind “backend” (as opposed to “polling”). For “http bind” url just use “/http-bind” and everything should work. Notice that if you open the client locally on your desktop (not served by the Apache) it won’t work because of the “same origin policy” mentioned before.

I hope you find this tutorial useful, it sure could have helped me… 🙂

iPhone tethering with Ubuntu

June 12, 2010 7 comments

Today was my first time I used iPhone tethering. Tethering means connecting computer to the internet using iPhone’s cellular connectivity (3G/EDGE). The iPhone connects to the computer via USB cable or Bluetooth and uses as a cellular modem. It’s useful when you’re away with a laptop and no wireless hot spots around.

There are many tutorials out there, however I found most of them misleading (advising to use third party software or jailbreak your iPhone – both unnecessary) and none of them for Linux. This tutorial is really easy and simple.

Step 1 – Enable internet sharing on your iPhone
On your iPhone goto Settings -> General -> Network -> Internet sharing -> On. If “Internet sharing” isn’t shown, open Safari and browse to: On this webpage click on “Tethering”, then select your country and your mobile carrier. Accept the profile and reboot your iPhone. After the reboot “Internet sharing” option is supposed to be shown. In my case, my carrier wasn’t on the list so I generated a custom file (the last option). The APN/User/Password were easily found using Google. However, “Internet sharing” stayed hidden. The funny thing is after I removed the custom profile it magically appeared. My iPhone version is 3.1.2 and it worked. I noticed they have warning for 3.1.3 so watch out if you got it.

Step 2 – Install necessary software on Ubuntu
As always, I provide instructions for Ubuntu. The driver you need is called “ipheth” and it depends on “libimobiledevice”. Now, you can find them both on Lucid’s official repositories. However, only version 0.9.7 of libimobiledevice is there, and while it may be enough for tethering, I recommend using the newer version which can be obtained from Paul McEnery PPA (for Karmic it’s still version 0.9.7):

# sudo add-apt-repository ppa:pmcenery/ppa

Executing: gpg –ignore-time-conflict –no-options –no-default-keyring –secret-keyring /etc/apt/secring.gpg –trustdb-name /etc/apt/trustdb.gpg –keyring /etc/apt/trusted.gpg –primary-keyring /etc/apt/trusted.gpg –keyserver –recv 3AE22276BF4F39C8D6117D7F4EA3A911D48B8E25
gpg: requesting key D48B8E25 from hkp server

gpg: key D48B8E25: public key “Launchpad PPA for Paul McEnery” imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

# sudo apt-get update

Now, install the driver (and it’s dependencies, which include  the library):
# sudo apt-get install ipheth-utils

Load the driver into running kernel
# sudo modprobe ipheth

At this point if you enter “dmesg” the last line should show something like “usbcore: registered new interface driver ipheth”

Step 3 – Plug your iPhone using USB cable
As soon as you connect your device a new interface should be plumbed, configured and ready to be used (in case you use network manager). You can get list of your interfaces with “ifconfig -a”. On your iPhone there suppose to be label saying “Internet Tethering”. If you don’t use network manager the “Internet Tethering” is triggered when you make DHCP request on that interface (for example, using “dhclient”).

That’s it. As promised, easy and simple. Thanks to Paul McEnery there are plenty of other cool iPhone related stuff you can install from his PPA (on Lucid).


Sending mail from command line

May 20, 2010 Leave a comment

Recently I wanted to add mail sending functionality to one of my scripts. This script runs on my desktop computer, so no fancy company mail servers/fixed IP/DNS records for me. When I googled it up I saw many different methods in varying complexity. My need was the simplest you can think of- just to send email. I didn’t care if it’s always from the same address. My solution was to use Ubuntu’s default exim4 mail server, with Gmail. Exim authenticates with your gmail user/password and the mail is always sent from the same address ( This is heavily based on this, although a little different.

First I had to install exim4-config, so:
# sudo apt-get install exim4-config

Then I needed to configure exim to work with Gmail:
# sudo dpkg-reconfigure exim4-config

My selections:

  • General type of mail configuration: mail sent by smarthost; no local mail
  • System mail name: localhost
  • IP-address to listen:
  • Other destinations for which mail is accepted: (leave blank)
  • Visible domain name for local users: localhost
  • IP address or host name of the outgoing smarthost:
  • Keep number of DNS-queries minimal: no
  • Split configuration into small files: no
  • Root and postmaster mail recipient: (leave blank)

Edit /etc/exim4/passwd.client (you can use gedit if you’re not comfortable with vi):
# sudo vi /etc/exim4/passwd.client

Add those lines (replace “user” and “password” with your own):

Finally update (refresh) exim configuration:
# sudo update-exim4.conf

That’s about it. To send the contents of /etc/motd as mail (just example):
# cat /etc/motd | mail -a “FROM:” -a “BCC:” -s “This is the subject”

The “BCC:” is optional of course. If you don’t specify “FROM:” the default is the current user.

If you don’t have the “mail” command then just install mailutils:
# sudo apt-get install mailutils

Happy mailing!

Ubuntu 10.04 Lucid Lynx

April 29, 2010 Leave a comment

Today, Canonical will release Ubuntu 10.04 LTS (long term support). I’m usually not so enthusiastic about new Ubuntu releases, but this time is different. They added some sweet features, well, at least for me, which didn’t get proper public relations. This is not a comprehensive review of the new features. It’s about new features I find cool or bad enough writing about, from a desktop user point of view.

First, I must say I love Ubuntu. In each release they turn some of the most annoying tasks (for linux newbies) into trivial and intuitive. It has great documentation, community support and amazing software package repositories. It is also widely supported by third party vendors. Second, they usually add performance boosts and cool new features with new releases. Third, you can order official CDs for free. What’s not to love ?

So, what do we get this time ? As always with ‘LTS’ releases, three years of (bug/security fixes) support. A fresh new beginner’s getting-started manual which looks very promising. Some crap as well: new look and feel and social networks integration. As if it’s that hard to change the look or use all-in-one social networks client…

Performance boosts. First, boot speed improvement. They already made a big leap from 9.04 to 9.10, and now again ? sounds delicious. “Super fast” boot for SSD based machines such as netbooks. Sounds very delicious. Second, faster suspend/resume for your netbook that will “extend battery life”. Excuse me for being skeptical, but come on… improving speeds are always good, but declaring it will save battery ? I don’t buy it.

Ubuntu One enhancements. I never got the deal around Ubuntu One. It suppose to be a personal cloud that keeps your files, notes, bookmarks and contacts on the net, but we already had these services long time ago (for example Gmail’s contacts which can be synced to your mobile, Dropbox file storage, or Delicious bookmarks). Anyway the new enhancements are better desktop integration, and new Music Store. For me, they’re both useless but I guess Canonical deserves it’s chance to fight Apple’s music store, plus, it’s DRM-free.

Software Center 2.0. Supposedly better interface for software installation and maintenance. I haven’t seen this one yet, but it sounds just like a GUI facelift. The underlaying software deployment mechanisms stay the same (apt/ppa repositories).

The sweet features I mentioned in the prologue: inclusion of libimobiledevice in official repositories. This is a software library that supports iPhone, iPod Touch and iPad devices. Programs built on this library provides filesystem access, music/video sync, internet tethering, apps installation, springboard icon management, gnome integration, and much more ! I’ve no idea how it got such a lousy public relations but for me that’s the real killer app !

EDIT: For now only version 0.9.7 of libimobiledevice is in the repositories. It means that only music sync can be done out of the box. It’s a shame. Two weeks ago, I asked the official maintainer of the packages to make packages for 1.0.0, and I thought he told me it would be included in Lucid release, but I misunderstood him. He actually told me that it’s too close to Lucid’s release for inclusion. I apologize for the (partially) wrong information. Anyhow, one can still build 1.0.0 from sources and use it. If there would be enough demand I would write an How-To guide. Leave a comment or send mail if you’re interested.