Ali Ayoub's Blog

2013-01-30T04:47:00.000+02:00

ويحك يا دنيا رميت سهماً - اصبت من بين صفوفنا خطيبها

وان كان اوان المنيه مستقدراً -لا اصنفت حين ظفرت سليمها

الم تصغ وقت دعينا سراً - رب لا تهمد ذي الدار سراجها

وان عصينا, فلنا فيها امـاً - لا تعص والداً ولا تقطر بدمعها

رضينا ربنا بالديجور داراً - راجيك ان ينير الجنان فردوسها

How to Stop Receiving Catalogs

2012-11-26T18:04:00.001+02:00

Mozilla Thunderbird & Microsoft Outlook & Linux Patches

2012-08-10T02:48:00.002+03:00

Tested on Thunderbird 14.0 (2012)

Microsoft Outlook is commonly used by many enterprises, it has a lot of nice features, but it cannot be used by Linux kernel hackers to exchange Emails and submit/review patches, because it doesn't support the formatting required by the Linux kernel community, Outlook client does "too much" to beautify the Email, and end up breaking the Email headers and formatting, in such a way that all attempts to fix it have failed.

Mozilla Thunderbird on the other hand, has very nice GUI interface, and can be configured as you wish. It also supports Apple OS X.

So if your company uses Microsoft outlook for internal Email exchanges, and you'd like to take part in sending/receiving Emails with the Linux kernel community, you may find it useful to move to Thunderbird.

Note that Thunderbird doesn't support Microsoft Exchange server (w/o IMAP/POP3), so you may want to have separate Email email for Linux kernel development (could be even a Gmail or Google Apps Email, this is good for archiving and for searching Emails). My attempts of using Thunderbird with Web Outlook interface didn't show good results, also using software proxy solutions such as DevMail showed very low speed. So I don't recommend making Thunderbird work with Microsoft Web outlook or Exchange server if it's not supported natively in Thunderbird (as for version Thunderbird 14.0 - 2012, it's not supported).

Configuring your Email with Thunderbird is pretty easy, the automatic configuration tools that comes with the Thunderbird client did the job, and it worked like a charm.

Now the tricky part is how to configure Thunderbird Email formatting to work properly with Linux patches. I found some links that explains how to do so, but the instructions seem to be outdated. Below is step-by-step instructions to configure Thunderbird properly for Linux kernel patches submission/reviews or discussions (tested with Thunderbird 14.0).

1. Go to Tools/Options/Advanced, under General tab, click on Config Editor

2. Set the following:

mailnews.send_plaintext_flowed = fals
email.identity.default.compose_html = fals
eprefs.converted-to-utf8 = true
mail.wrap_long_lines = true
mailnews.wraplength = 72

3. You're ready.

Note: if for some reason, you've received an Email on Outlook, and you'd like to reply from Thunderbird, you can export the Email from outlook, and import it into Thunderbird.
- To export an Email from Outlook: drag and drop the Email item to (e..g) your desktop

- To import to Thunderbird: File/Open saved message, then select "all files" and open the Outlook exported Email.

- You may want to automatically CC your outlook address on all outgoing Emails from Thunderbird: Go to Tools -> Account Settings, then Copies and Folders (under you e-mail account name). CC/BCC any other Email address/addresses.
- To send an Email from Thunderbird "on behalf of" your Email in outlook, you can add new identity in Thunderbird by going to Tools/ Account/ Manage Identities, then you need to enable the new identity also on the server side, in case of Gmail-based account, go to Gmail/ Settings/ Accounts and Import, then click on "Add another email address you own", to change the default "From" field in Thunderbird you may find CorrectIdentity plugin useful.

Automatic subtitle with VLC on MAC

2012-06-23T10:55:00.001+03:00

Subdownloader is a nice application to automatically download the subtitle of a movie.
It parses your files and connects and uses OpenSubtitles to get the list of available subtitles for a particular movie, it can be configured to fetch your favorite language(s).

With VLC player, this would be a perfect combination.
To enable "play" button on Subdownloader to automatically launch VLC player, go to Preferences -> Others -> and then fill the fields as in the snapshot below.

How to save websites passwords

2012-06-21T03:11:00.000+03:00

There are too many web accounts to remember, and their username/password plicy may vary, I bet you recall all of them. On the other hand, it's hard to trust the tools out there that promise to collect all your passwords and back them up.

Since I use my Gmail daily, and it has valuable information, it also has 2-step verification process for extra security, so I will take the chances and use Gmail to store my web account passwords. this way I need only to remember my Gmail account password (this is no big deal) and then you can use Gmail search engine to easily find the website username/password you're looking for.

Normally websites send you a verification Email with your username to your Gmail account, I forward this Email to myself with the password, and move it to "passwords" label.

If I change my password, I look for the Email in my Gmail account that holds my previous password, and reply (to myself) with the newer password
Many times, Google Chrome saves my password, with time it holds a lot of passwords that most likely I forgot.. so once in a while, I export all Chrome passwords and send it as a text file to my Gmail account (use text file to allow Gmail search to find them for you). This tool (ChromePass) is pretty simple and does the job.

Some sites don't allow you to save the password (when you log in, you won't see the "save password" button (in chrome). When you hit such a website, and you still want it to save the password:

Right Click on the username field, and select "inspect element"
Find the token autocomplete="off" and change it to "on", hit enter
go back to the username/password fields, and you'll see the "save password" button right after you fill your information

Synergy for PC/MAC

2012-04-16T23:35:00.002+03:00

Synergy is a cool app that lets you share your mouse and keyboard between multiple computers. If you use Macbook Air (2011), you probably know that the embedded graphical controller doesn't support dual monitor.. this is where Synergy become handy.

I've install Synergy today on my DELL 6410 laptop as a server, and on my Macbook Air 2011 as client. The idea behind the application is great, however it still have some bugs especially in the interoperability part between PC and MAC.

The first problem I've encountered is that the shift key doesn't pass from PC server to MAC client, thanks to this post, I installed the following versions and was able to have successful integration:
Win 7 - x86 version 1.4.8
MAC 10.7.x - x86_64 version 1.4.7

Search Linux Kernel code from Google Chrome

2011-10-25T08:31:00.003+02:00

If you're a kernel developer, you must be familiar with Linux Cross Reference (LXR) sites.. there are a few of them out there, but I find http://lxr.linux.no the most convinent and the the fastest, it also uses a newer version of LXR than others.

If you're a Google Chrome user, you can easily add a new custom search type for LXR:
1. Open chrome and go to: chrome://settings/searchEngines
2. Add the following entry: Search engine: lxr.linux.no, keyword: lxr, Query: http://lxr.linux.no/linux/+search=%s

3. Now you can search for any Linux kernel symbol directly from chrome, for example: go to the toolbar and type "lxr skb_dst"

4. Chrome will build the URL query for you, and results are shown directly in the browser tab.. happy kernel browsing :)

Steve Jobs 1955-2011

2011-10-06T02:09:00.002+02:00

Apple website snapshot Oct 5th 2011, 5:10 pm

Sony HX100v - GPS location

2011-06-23T11:04:00.002+03:00

The new Sony HX100 is GPS-enabled, this feature is very cool, especially when paired with Google Picasa.
For Example, when you upload a photo to picasa web album, the location on the map is viewed automatically (make sure that location permission is granted).

And, also through Picasa application on your computer, if you have Google Earth installed, you will be able to see a small icon of Google maps on the photo, then you can click on Geo-Tag button, and Google Earth will be launched and will show your picture location.. neat ha?

Sony HX100v - 10fps Collage

2011-06-23T10:22:00.006+03:00

Finally got my new Sony HX100v, a lot of features I'd like to try.

My favorite feature is the 10 frames per second (each is full resolution of 16.2MP).. this feature existed in the previous HX1 as well.. first day trying me new camera I got this collage.. click on the picture for better resolution, or check zoom-in option under this link.

To make collage (especialy for such a nice feature) you can use Google Picasa and follow these simple steps.

Select the photos and click on Collage:

Edit the Collage settings, and generate the collage photo!

Bird's kick vs. Spartan's kick

2011-06-19T00:47:00.003+03:00

I found it hard to ignore the analogy between these two..

This is Spartaaaaa
I mean: This is.. my bird-girl-frieeeend[kick]

Xen Installation on CenOS-5.5

2010-12-09T01:11:00.017+02:00

As part of my work, I had to bring up Xen Servers setup, and install some virtual machines.
I've been working on VMware ESX Servers for a while, and I must admit that VMware products are way more mature than Xen products. Below step by step installation of Xen over CentOS-5.5 and how to bring up and configure DomU Virtual Machines.

Dom0 Installation:
-----------------
1. Install CentOS-5.5 OS
   ISO is downloadable from here
2. Install Xen kernel and Tools:
# yum install kernel-xen kernel-xen-devel xen

# yum install virt-manager
# yum install virt-viewer
3. Edit /etc/grub.conf and select xen kernel

default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-194.26.1.el5xen)
   root (hd0,0)
   kernel /xen.gz-2.6.18-194.26.1.el5
   module /vmlinuz-2.6.18-194.26.1.el5xen ro root=LABEL=/ rhgb quiet
   module /initrd-2.6.18-194.26.1.el5xen.img
title CentOS (2.6.18-194.el5)
   root (hd0,0)
   kernel /vmlinuz-2.6.18-194.el5 ro root=LABEL=/ rhgb quiet
   initrd /initrd-2.6.18-194.el5.img
4. Reboot the machine
5. Check kernel name, it will have xen substring:

# uname -a
Linux eng-023.mti.mtl.lab.com 2.6.18-194.26.1.el5xen ...
6. On my machine, yum installed Xen version 3.0.3:

# rpm -qa|grep -i ^xen-[0-9]
xen-3.0.3-105.el5_5.5

DomU Installation:
------------------
1. run virt-manager from dom0
2. select server name in the table, and select "new"
3. configure the virtual machine, when you get to the installation media, you better have the installation dir (extracted iso) available through on your network (check this link if you want to bring up your own apache) note that for full Linux installation (e.g., for RHEL-5.5) you need more than 4GB virtual disk space (I use 8GB).
4. when installation is done, machine will reboot and come up with bridged network connection
5. If you configured your VM to use DHCP, then you're ready, go ahead and ping the WAN.
- For more info on how to use virt-manager to install DomU instance (with snapshots) check this link.

DomU Network Configuration:
---------------------------
Xen supports three modes for network virtualization:
Bridging, Routing w/o NAT, Routing with NAT, each one of them need to be configured differently.

By default, the network is set up in bridging mode.
To change the network configuration, there are two main configuration files:
# /etc/xen/xend-config.sxp (hypervisor conf)
# /etc/xen/VM-NAME (virtual machine conf)

DomU in Bridging mode:
----------------------
1. Make sure that xend-config.sxp has the following lines:
   (network-script network-bridge)
   (vif-script vif-bridge)
   To use different netdev (rather than eth0) use the line:
   (network-script 'network-bridge netdev=eth1')
   To create multiple bridges, you must create your own script.
   For example, in xend-config.sxp add:
   (network-script network-bridge-multi)
   The cerate the file (with +x permissions):   # cat /etc/xen/scripts/network-bridge-multi
   #!/bin/sh
   dir=$(dirname "$0")
   "$dir/network-bridge" "$@" vifnum=0 netdev=eth0 bridge=xenbr0
   "$dir/network-bridge" "$@" vifnum=1 netdev=eth1 bridge=xenbr1
   "$dir/network-bridge" "$@" vifnum=2 netdev=eth2 bridge=xenbr2
   check this link for more details.
2. Configure DomU virtual interfaces,
   Edit /etc/xen/VM-NAME and examine the following line:
   vif = [ "mac=00:16:36:69:0d:0b,script=vif-bridge,bridge=xenbr2" ]
   where xenbr2 is an example of the bridge name
3. Note that if the netdev of the bridge your going to use was created after machine reboot, then you need to restart the xen network script, for example:
# /etc/xen/scripts/network-bridge stop
# /etc/xen/scripts/network-bridge start
If the pethX interface you expect does not come up, try to reboot the machine (I noticed that in Xen 3.0, the network-bridge may fail to create the pethX interface if you restart the script few times, reboot solved the issue)
4. Make sure that the bridge as appear in brctl is output, is configured as expected:
#brctl show xenbr2
bridge name bridge id STP enabled interfaces
xenbr2 8000.00.. no vif2.0
   peth2
If you configured your system in the past to work in routing mode, you may see virbr0 instead of xenbr0, to revert these changes, run:
# service libvirtd stop; chkconfig libvirtd off
If for some reason the peth2 that coresponds to your netdev is not attached to the bridge, then find your peth:
# ethtool -i peth2
and then add the interface to the bridge:
#  brctl addif xenbr2 peth2
If for some reason, peth2 link is down, run:
# ip link set peth2 up
At this point you can run the VM, configure the IP, and heck ping-pong, you can tcpdump the bridge (xenbr2) and its slaves to check the packets flow.

DomU in Routed mode:

--------------------

Note that most of the tips of this section are based on this link.
1. Update your grub entry to include the following parameters:

title Kernel-XXX-xen
   root (hd0,5)
   kernel /boot/xen.gz
   module /boot/vmlinuz-XXX-xen root=/dev/sda6 vga=0x31a resume=/dev/sda5 splash=silent showopts
   module /boot/initrd-XXX-xen
2. Set netloop driver module parameter, edit /etc/modprobe.conf and include the line (to top netloop from creating 8 useless vifs):
options netloop nloopbacks=0
3. Reboot Dom0
4. Configure Dom0 networking, edit /etc/xen/xend-config.sxp and include the line:

(network-script network-route)
(vif-script vif-route)
5. Configure DomU networking, edit /etc/xen/VM-NAME and include the line:
vif = [ 'mac=00:16:3e:33:22:11, ip=192.168.23.1, vifname=eth0' ]
Where the IP address, is the IP address you plan to give to vifname interface within the VM.
6. Power on the VM, and conifgure (for example) the eth0 interface to use the IP=102.168.23.1
7. Ping the IP address of Dom0 (run ifconfig from Dom0 and check your netdev IP, must start with 192.x.x.x [depends on your mask]).
8. To ping other machines outside the GW, need to configure the default GW in the VM, this can be done in many different ways, for example:
route add default gw 192.168.23.254 eth0

Notes:
------
- To install KVM on CentOS, check this link

Troubleshooting:

----------------

- If you get the error message:

ERROR unable to connect to 'localhost:8000': Connection refused

You probably don't have xen-http-server enabled, edit:

/etc/xen/xend-config.sxp

and include the line:

(xend-http-server yes)

then restart xend:

/etc/init.d/xend restart

Google Currency converter

2010-12-02T23:23:00.003+02:00

Nice and simple Google Currency converter:
Example, from USD to ILS:

If facebook existed years ago

2010-11-15T09:05:00.000+02:00

like it!

GIT Tips

2010-10-26T05:02:00.005+02:00

While looking for GIT configuration for "signed-off-by" line, I found this nice link for GIT tips.
It has nice git-config commands that you might find useful in general.

Specifically, to automaticaly add the "signed-off-by: NAME " line into your git commits, run the following two commands:

git config user.name 'Your name'
git config user.email 'my@email.com'

I also found this nice link while searching for git cherry-pick, thanks for sharing.

Extract vSphere Installation Bundle

2010-10-05T05:55:00.010+02:00

If you happen to need to extract vSphere Installation Bundle (vib), this can be done by running the following:

- Extract the zip archive:

unzip BUNDLE.zip

Two files will be created, metada.zip and VIB.vib

- Extract the vib archive

ar -x VIB.vib

The following files will be created:

control.tar.gz

data.tar.gz

debian-binary

descriptor.xml

short.rpm sig.pkcs7

- Extract data.tar.gz
tar -xzvf data.tar.gz

The result would be the files you are looking for. enjoy!

Note:

- ar command is normally not available on ESX Server, run this command on Linux.
- I added support to this script to recognize vib extension.

Run as daemon in Linux

2010-09-30T23:27:00.008+02:00

In Linux, when a command is executed from a terminal window, it will be child of that window's PID. For example, see below how xlogo is parent of the terminal:

# open terminal window:
# echo $$

4830

# xlogo &

4956

# ps -l | grep xlogo

0 S 1049 4956 4830 0 75 0 - 9979 - pts/11 00:00:00 xlogo

As a result, whenever you close the terminal (parent) window, the xlogo will terminate.

If you wish to run your application as daemon, use the command NOHUP(1), this will make the running application immune to hangups. For example, see how xlogo is child of PID 1 (the init process):

# open terminal window:

# echo $$

4830

# nohup xlogo &

5013

# close the terminal window

# ps -l|grep xlogo

0 S 1049 5013 1 0 75 0 - 9979 - pts/11 00:00:00 xlogo

SSH Host key verification failed

2010-09-28T20:09:00.005+02:00

If you keep getting this annoying SSH failure:

I used to edit known_hosts file and remove the record that coresponds to the remote host IP,

a simpler way is to run the command:

# ssh-keygen -R REMOTE_IP

Linux Sign Generator

2010-09-28T06:01:00.004+02:00

I came across this nice image generator of Linux penguine holding a sign with custom text, give it a try.

I recommend using 20pt pixels font with black color, like the one I used in this sed post.

You can also edit the link directly and just replace the text, for example, to generate a sign with above setting and the test "Linux Sign Generator" then the link would be:
http://www.images-graphics-pics.com/signs/signs/linux/?allow=&text=Linux+Sign+Generator&fontsize=20&font=pixels&color=black&move=20

Note: the character + used for spaces

Sed by Example

2010-09-28T05:44:00.011+02:00

As you probably know, sed is a very powerful tool in Linux for filtering and transforming text.

I was looking for some commands with regular expression to process some configuration files in Linux, and I found this link that teaches sed by example, it's informative and easy to understand.

Useful links:

http://www.amirwatad.com/blog/archives/2009/05/30/convert-camelcase-to-underscores-using-sed/ http://sed.sourceforge.net/sed1line.txt http://www.ibm.com/developerworks/linux/library/l-sed1.html

Note: If you read Arabic, sorry for the picture, no offence (I still find it funny) If you do not read Arabic, never mind.

Check multiple machines availability

2010-09-20T04:59:00.007+02:00

Usually, administrators check machines liveness by sending ICMP echo request (aka ping request).

I found this tool very handy to check the liveness of multiple machines very quickly from command line. The tool is called fping, and it can be installed on Linux using this tar ball.

Example:
Define your machines IPs configuration file:
# cat machines.ips
10.20.1.19
10.20.1.20
10.20.1.21
10.20.1.22
10.20.1.23
10.20.1.24
10.20.1.25
10.20.1.26
10.20.1.27
10.20.1.31
10.20.1.32

Now, run fping to check the machines availability:
# fping -f machines.ips -r 1 -t 100
10.20.1.19 is alive
10.20.1.20 is alive
10.20.1.21 is alive
10.20.1.22 is alive
10.20.1.23 is alive
10.20.1.24 is alive
10.20.1.26 is alive
10.20.1.27 is alive
10.20.1.31 is alive
10.20.1.32 is alive
10.20.1.25 is unreachable

Script Header Generator

2010-09-20T04:15:00.008+02:00

If you write a lot of scripts, you are aware of the importance of the scripts headers.
General, script header define the script language, usage, description, author..

I wrote this script, that generates a script header based on the template below, the script tries to identify the script language and usage automatically, in addition to some other fields, variables that need to be set manually are marked with "TBD" such as script description.

Feel free to change the AUTHOR and AUTHOR_EMAIL in the script to your own strings.
I found this scripts very useful to fix the header of hundreds of scripts I have that didn't include the appropriate header. Share and Enjoy.

Example, to generate the header of the script test.py, run:
$ ./create_header.py test.py

#!/usr/bin/env python
#===========================================
#
# FILE: test.py
# USAGE: ./test.py [--help|--version]
# DESCRIPTION: Tests how fast you can type A-Z
# REQUIREMENTS: python, finger
# BUGS: N/A
# NOTES: Dummy File
# AUTHOR: Ali Ayoub
# EMAIL: ali@ali.ali
# COMPANY: LIUB, Ltd.
# CREATED: 09.19.2010-19:05:39
# REVISION: 1.2
#===========================================

Tip:
Python Rocks.

The ARP Flux Problem

2010-09-20T02:18:00.006+02:00

If you spent a lot of time trying to understand why a network interface in Linux fakes ARP replies on behalf of another interface, you may be facing the ARP flux effect! Yes, this is how it's called, and yes, you spend many hours debugging problems due to this weird behavior.

Surprisingly, this is a known behavior of Liux ARP module, when a a machine has multiple network interfaces, as stated in O'Reilly Book: Understanding Linux Network Internals:

The solution of the flux problem is through altering the system sysctl parameters, few websites (see references below) suggest how to make the suitable changes.

To make this process easier, you can use this script to set the right values into the procfs files.
To make the changes permanent (kept among reboots): the following can be added to your /etc/sysctl.conf file:
sysctl -w net.ipv4.conf.all.arp_ignore=1
sysctl -w net.ipv4.conf.all.arp_announce=2

Tip:
To flush the ARP table in Linux, use this helper script.

References:

http://wiki.openvz.org/Multiple_network_interfaces_and_ARP_flux

http://www.inlab.de/balanceng/faq.html
http://linux-ip.net/html/ether-arp.html

objdump parser

2010-07-30T04:50:00.007+03:00

If you've been programming in Linux kernel, you must had the chance to debug kernel oops using objdump.
Normally, you invoke objdump with the name of the problematic driver, and then parse the output based on the information printed in the call trace of the kernel oops. Here is a nice example.

Among many hexadecimal numbers and function names that are printed in the call trace of the kernel oops, the most important piece of information is the function name and the offset: for example:
vnic_login_create_2+0xd1

I wrote this script that receives the function name and offset as a pointer, and prints the source file name and line number that caused the oops.

For example:
# objdump_parser.py vnic_login_create_2+0xd1 drivers/net/mlx4_vnic/mlx4_vnic.ko

vnic_login_create_2+0xd1 = 0x6e3 => drivers/net/mlx4_vnic/vnic_data_main.c:210

"always on top" option for Windows

2010-07-21T00:58:00.001+03:00

Always On Top Maker is a tiny interface less tool to make any window "always on top", or, make a topmost windows not always on top. How to use: Run AlwaysOnTopMaker.exe, then you can use 2 hot-keys, one is CTRL-ALT-T, is to switch the foreground application "always on top"/"not always on top", the other hotkey is CTRL-ALT-Q, is to exit Always On Top Maker.

Reference:
http://softzilla.blogspot.com/2009/06/always-on-top-windows-tools-best-always.html