Capturing video off your desktop with xvidcap on Linux

What is xvidcap?

It is a small tool to capture things going on an X-Windows display to either individual frames or an MPEG video. On Windows machines there are commercial tools like Lotus ScreenCam or Camtasia. From my experience, new user will take some time to take off with a video. I just think it needs more work on user-friendliness.

Where to download?
If you use Fedora, you can install with yum: yum install xvidcap
If u use Ubuntu or Debian, you can install with apt-get : apt-get install xvidcap
or for advanced user, you can download the source code here.

My desktop
Below is a video off my desktop I took with xvidcap. On the video, you can see that I was showing off Compiz. :)

Dansguardian - web content filtering for all

What is dansguardian?

(Excerpt from dansguardian's website)

DansGuardian is an award winning Open Source web content filter which currently runs on Linux, FreeBSD, OpenBSD, NetBSD, Mac OS X, HP-UX, and Solaris. It filters the actual content of pages based on many methods including phrase matching, PICS filtering and URL filtering. It does not purely filter based on a banned list of sites like lesser totally commercial filters.

DansGuardian is designed to be completely flexible and allows you to tailor the filtering to your exact needs. It can be as draconian or as unobstructive as you want. The default settings are geared towards what a primary school might want but DansGuardian puts you in control of what you want to block.

DansGuardian is a true web content filter.

Where to download?

The latest beta when this article is published is 2.9.8.5. Download it here. Beta doesn't mean it is unstable. From my experience, it is a very reliable piece of software. Downloading source code and compile it yourself is the best way to take full advantage of its (latest) capabilities and speed.

My setup

I have more than 200 clients in my network. To provide a fast and reliable internet connection, I have to use a proxy server and dansguardian is used for filtering unwanted websites and scanning for viruses of downloaded files and websites.

Startup script
Startup script can be taken from [source dir]/data/scripts/systemv-init. Copy it to init.d:

~#cp systemv-init /etc/init.d/dansguardian

Run chkconfig to make it start across booting properly:

~#chkconfig --add dansguardian
~#chkconfig --level 35 dansguardian on

Note: For Fedora users, you may need to use /sbin/chkconfig instead of chkconfig.

How to upgrade?

If you have installed dansguardian via package manager, it is easy to upgrade it with package manager too. So you don't need to mess up with compilation and dependencies. It will take care of them for you. I like to download source code because I can download the latest and to take the advantage of its speed. You can not always get the latest packages with package manager and the package may not optimized for your machine. YMMV.

Steps:
1. Download the latest source code.
2. Extract it: tar xzvf dansguardian-2.9.8.5.tar.gz
3. cd into the source dir.
4. configure : ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --enable-clamd=yes
5. Run make : make
6. Install : make install

If you have previous version of dansguardian, please backup directory /etc/dansguardian/lists because installing the new one will overwrite all the files in it. You don't want to refill all the sites you have entered in all files in there for banned sites , exception site (unfiltered sites) etc2.

Configuration
The main configuration file for dansguardian is /etc/dansguardian/dansguardian.conf. It is heavily documented. Tkae your time to read the comments in there before modifying. Below is the most important directives to be modified (example):

filter_ip = 192.168.5.2
filter_port = 3128
proxy_ip = 127.0.0.1

Note: 192.168.5.2 is the IP which dansguardian will listen on. If left empty, it will listen on all IPs. For increase security, please state IP(s) that it needs to listen on. filter_port is the port it will bind to. proxy _ip is the ip where the proxy server (daemon, e.g squid) listens on. Note that you must run proxy server before running dansguardian or it will fail to start.

Integration with antivirus

Dansguardian can use antivirus for content scanning of viruses. I use clamav for this. You need to uncomment the directive contentscanner and modify file /etc/dansguardian/contentscanners/clamdscan.conf.

contentscanner = '/etc/dansguardian/contentscanners/clamdscan.conf'

In this file, change clamdudsfile like this :

clamdudsfile = '/tmp/clamd'

/tmp/clamd is the socket file for my clamav daemon (clamd). Change it accordingly.

Repositories for Fedora Core 6

Fedora Core is in rapid development. Repositories or in short repos (plural of repo) are servers which provide packages for Fedora Core users to install and update packages. For those who likes to live on the edge should enable testing repo. For newbie, you can use pirut or go to Application --> Add/Remove Software and enable the testing repo. Be warned that the packages provided are not stable. They can even make your computer system hang and your CD drive burnt ;). I don't like it. I like everything to be stable and I have experienced how it was to be living on the bleeding edge. Things were not that good. :D

Beside core, updates and extras repositories, you might need to add livna and kde repositories too. These sites provide non-free/proprietary packages like mp3 support and proprietary display drivers (ATI and NVIDIA). The kde repo stated above provides unofficial kde packages from kde community itself. The packages comes as updates for the packages provided by official Fedora repo.

To add livna repo, run this command :
rpm -ivh http://rpm.livna.org/livna-release-6.rpm

To add kde repo, download this file using wget:
wget http://apt.kde-redhat.org/apt/kde-redhat/fedora/kde.repo

and put this file in /etc/yum.repos.d/

Afterthat, try checking updates by running yum check-update. You should see many updates come from both repos.

Setting up wireless with Mandriva 2007

I rarely install Linux on laptop. It was great to have one and saw how Linux distros progressed in this area. Since last week, I have been a responsible person for one of my office's laptop. I tried installing Fedora Core 6 on it. It was no good. After a couple of minutes, it started to become slower like something was going on in the background. It was so annoying. I tried upgrading the kernel and all the latest updates using yum but to no avail. Of course your mileage may vary.

Mandriva 2007

With Mandriva 2007, I was in luck. I got the DVD from LinuxForYou magazine. I am no stranger with Mandriva. I have been using it for 5 years and one of servers I managed using it. As any desktop-oriented distros, Mandriva is one of the user-friendliest distros out there. It is good and will be better in the future.

Wireless

My laptop is Intel-based. What i mean here is the wireless, CPU and VGA chipsets are from Intel. My wireless is ipw3945. No driver for this chipset I could found in the DVD. After googling, the driver is here. This is the kernel module (driver) for the wireless chipset. Hence, I activated it with modprobe : modprobe ipw3945. It created a device called eth1 (eth0 was reserved for wired connection).

Connecting to AP
Open Mandriva Control Center and go to Network And Internet:
Click on the Wireless connection.


As you see in the diagram below, the AP signal was detected and shown. The button Disconnect should be Connect before you connect your laptop to the AP.


If the connection is successful, then you can connect to your network and internet. Contact your network administrator if you have problem. Good luck.

Setting up a printer with CUPS

Printing with Linux has never been easier with CUPS. I had bad experience long ago with lpr and lprng before when printer support was still scarce. Nowadays, setting up a printer on Linux is like a 'walk in the park'. Thanks to CUPS.

HP LaserJet 1020

In my office, my pc is the only pc running Linux (FC6 to be specific) and the others are (you bet!) Windows (XP Pro Edition to be specific). My colleague sitting nearest to me is a webmaster. Her pc is connected to an HP LaserJet 1020 printer and shared with name HP1020.

Get ready the required packages
I need to print to that printer. So I decided to install SAMBA and CUPS packages for that purpose.

Finding the driver

DON'T use the driver for this printer packaged with FC6. It won't work. I tried it but I think you must try it too to prove me wrong. Of course YMMV. The driver is here. Before that, you have to read what the author's have to say on the website. It's important!. Follow the instructions on how to compile and install the ICM and the firmware files. Included in the tarball is the PPD file for working with the printer.

Connect to the printer
Once all the above completed, add the printer to cups so that she knows where to send files for printing.

Put the name, location and description for the printer. At this stage, it won't set the 'real' things yet.


Select the device for the printer. It obviously "Windows Printer via SAMBA".

The device URI should be in this form : smb://servername/sharename or smb://Workgroup/servername/sharename. To know the sharename, you can use this command to list all shared folder on the server servername: smbclient -L servername

At this stage, click Browse button and find the PPD file in the folder where you extract the tarball. Find the folder named PPD in there and click on the file named HP LaserJet 1020.ppd or a file named after your printer model and then click Add Printer. Now you are done setting up the printer in CUPS system. To see whether the printer has been added to the system, click Printers tab. If it is listed, then you are now good to test the printer by clicking on Test Printer button. For now, the driver supports printing in Black and White only. Works are in progress though to support color printing.

Good luck.

Setting up webcam on Linux (ZC0301)

It was a rare occasion if I got my hand on a web camera. This time I borrowed it from my colleague. Last time I couldn't get it to work. I didn't remember why. But this time, it was easy as ABC.

Spec:
Model : Z-Star Microelectronics Corp. Havit 3808 (this is what it says on the tin)
Chipset : ZC0301 (from lsusb)

Last time I looked at http://zc0302.sourceforge.net/ for the driver. It has been inactive for a long time. Still so far, the driver for ZC0301 is still not supported.

This time: I looked at spcaxx project page at http://mxhaard.free.fr/spca5xx.html. The webcam I was using supported. As stated on the website, for Fedora Core 6 users like me can download the driver here. The driver is actually a kernel module and after installing it, you can load the module with modprobe : modprobe gspca

When done, open your kopete, and click Settings --> Configure.. --> Device and see whether it detects and display video from the webcam. Then you can enjoy webcam session with your friends and acquaintances.

Good luck!

postfix - mailbox size limit and message size limit

postfix is my MTA of choice. I use it for my mailserver because its simplicity , security and sendmail-compatible (the widely used smtp in the world but not as secure). It is also extensible by plugging other servers for various purposes (antispam, antivirus,database etc).

I had one problem with file attachment larger than 10MB. Users couldn't send it although I have setup squirrelmail (SM) to be able to attach files summed up more than 20MB and I had modified php settings as per here. The problem was not in SM setting. It was postfix. By default, attachment size that can be sent by postfix is 10MB ~ 10240000 byte. How did I know it? I looked in log file (for my system it is in /var/log/mail/errors. For other system, the file to look is /var/log/maillog). The line looked like this:

Feb 26 16:30:53 webmail postfix/sendmail[30775]: fatal: me@mymailserver.org(74): Message file too big

Solution

Open /etc/postfix/main.cf with a text editor of choice and find message_size_limit directive and change accordingly. If it is not there, add the directive like this:

message_size_limit = 20480000

This sets limit to 20MB.

Some other parameters you need to change are in file php.ini which is usually located in dir /etc. Set their parameters as above or higher values as below:

post_max_size = 20M
upload_max_filesize = 20M

reload or restart postfix when you're done:

service postfix reload

or

service postfix restart

There's also mailbox_size_limit directive. You need to change this if SM can not open mailbox sized more than 10 MB.

reference :
http://www.tek-tips.com/viewthread.cfm?qid=1073614&page=1