ssh as a proxy

Sometimes ports are blocked to your local machine and you can only get to them if you are on the client’s machine.

Let’s say you want to connect to port 21 on remote-server.com, but that port is only open to client.server.com.

ssh client.server.com -N -L 1337:remote-server.com:21

This opens port 1337 on your local machine, and fowards it to port 21 on remote-server.com, using client.server.com as a proxy.

quick start Linux + PHP + XDebug howto

Ever really debugged before? It’s a life changer. Forget dpm, dd, print_r, var_dump…

1) Install a debugger of your choice (NetBeans, protoeditor, Komodo, Eclipse…)

2) Install/Configure XDebug extension

pecl install xdebug

If you get errors regarding pecl, phpize or missing libraries, try installing the php-pecl and php-devel packages.

Go to /etc/php.d, or wherever your PHP configuration files live. If you see “xdebug.ini” move it to “00xdebug.ini”. THIS IS THE MOST IMPORTANT PART. We have to rename it because XDebug has to run before all other extensions. If you have other extensions like datacache, other debuggers (Zend), or optimizers, you should disable them. Otherwise, XDebug will show as loaded but it won’t work.

Edit 00xdebug.ini and put the following code in:

zend_extension=xdebug.so
;debugger
xdebug.remote_enable=1
xdebug.remote_handler=dbgp
xdebug.remote_mode=req
xdebug.remote_port=9000
xdebug.remote_connect_back=1
xdebug.remote_autostart=0
xdebug.idekey=netbeans-xdebug ;change to same ide key in your debugger
;profiler
xdebug.profiler_enable=0
xdebug.profiler_output_dir=/tmp
xdebug.profiler_enable_trigger=1
xdebug.profiler_output_name=cachegrind.out.%p.%R.%r

3) Check configuration
Check the output of “php -i” and paste it into http://xdebug.org/find-binary.php. It will yell at you if you did anything wrong.

4) Install the XDebug helper for Firefox or Chrome
This allows you to toggle debugging on and off for local sites.

Debugging
Figure out how to enable debugging in the debugger of your choice and set a break point at a function call. Open up the page in your browser and make sure you use the XDebug helper to set debugging on. Your debugger should halt at the line. Now you can see all your local variables and dive into function calls.

Profiling
XDebug also profiles. Making a web request with ?XDEBUG_PROFILE=1 in the URL will enable the profile and dump to xdebug.profiler_output_dir. You can take these dumps and use a program like cachegrind to analyze the request.

I use Fedora on a daily basis to debug using Zend Server as my stack, but this will also work on any other configuration (Debian, Mac) – just change the paths to what they are on your system.

taking a screenshot with phpunit and selenium RC

PHPUnit has built in support for taking a screenshot with Selenium and storing it locally (as in, on the server that is running the firefox instance)

This doesn’t work well when you’re running selenium RC, because you won’t know what server firefox eventually runs on.

Fortunately, PHPUnit also implements captureEntirePageScreenshotToString(), which will return a base64-encoded PNG that you can decode and store locally (for example, to provide to Jenkins as an artifact)

In this example, I want to capture the screenshot when the test ends, or when it fails.

You can implement this code elsewhere if you wanted to take screenshots on failure only, after each test, etc…

raid5: cannot start dirty degraded array for mdN

rebuilding a software raid array and stuck with this error? for example, I was rebuilding on a live array and the server took a dive.

try tricking the array into believing its clean, then try to add a new drive or start the array again.


echo "clean" > /sys/block/md0/md/array_state
mdadm /dev/mdN -a /dev/sdXN
or
mdadm --manage /dev/md0 --run

then do a cat /proc/mdstat

raid should be rebuilding!

replace dolphin with konqueror

Dolphin is still missing some features that I have set up in Konqueror.

But EVEN AFTER changing your preferred “file browsing” application to Konqueror under System Settings ->Default Applications, Dolphin still runs on mostly any folder operation. I found that the easiest way to get Konqueror to run instead was to symlink dolphin to konqueror. as root:


cd /usr/bin
mv dolphin dolphinx
ln -s konqueror dolphin

Now Konqueror runs for everything.