PHP from commandline starts gui programs but apache doesn't - php

First, I read some threads by people with similar problems but all answers didn't go beyond export DISPLAY=:0.0 and xauth cookies. So here is my problem and thanks in advance for your time!
I have developed a little library which renders shelves using OpenGL and GLSL.
Last few days I wrapped it in a php extension and surprisingly easy it works now.
But the problem is it works only when I execute the php script using the extension from commandline
$php r100.php(i successfuly run this from the http user). The script is in the webroot of apache and if I request it from the browser I get ** CRITICAL **: Unable to open display in apache's error_log.
So, to make things easier to test and to be sure that the problem is not in the library/extension, at the moment I just want to start xmms with following php script.
<?php
echo shell_exec("xmms");
?>
It works only from the shell too.
I've played with apache configuration so much now that I really dont know what to try.
I tried $xhost + && export DISPLAY=:0.0
In the http.conf I have these
SetEnv DISPLAY :0.0 SetEnv XAUTHORITY /home/OpenGL/.Xauthority
So my problem seems to be this:
How can I make apache execute php script with all privileges that the http user has, including the environment?
Additional information:
HTTP is in video and users groups and has a login shell(bash).
I can login as http and execute scripts with no problem and can run GUI programs which show up on display 0.
It seems that apache does not provide the appropriate environment for the script.
I read about some difference between CLI/CGI but cant run xmms with php-cgi too...
Any ideas for additional configuration?
Regards

Sounds bit hazard, but basically you can add even export DISPLAY=:0.0 to apache start-up script (like in Linux /etc/init.d/httpd or apache depending distro).
And "xhost +" need to be run on account which is connected to local X server as user, though I'm only wondering how it will work as php script should only live while apache http request is on-going.
Edit:
Is this is kind of application launcher?, you can spawn this with exec("nohub /usr/bin/php script.php &"); .. now apache should be released and php should continue working in background.

In your console, allow everyone to use the X server:
xhost +
In your PHP script, set the DISPLAY variable while executing the commands:
DISPLAY=:0 glxgears 2>&1

Related

Run PHP script in background on Apache start/restart(Windows Server)

I've installed Apache 2.4 with PHP 5.4 on Windows Server 2008 following instructions from this manual:
Apache installing manual.
Apache runs as a service now.
My application requires a php websocket script to run in the background. I'm running it manually with:
php myscript.php
The question is: Is there a way to start a background script automatically on system(apache) restart?
I found the following topic, but I didn't know where I could find an apache startup script for Windows.
Any help will be much appriciated.
I come up with a solution :)
Create an environment variable pointing to your Apache directory
APACHE_HOME = C:/PATH/TO_APACHE
Rename %APACHE_HOME%\bin\httpd.exe to %APACHE_HOME%\bin\httpdVendor.exe
Create a batch file and put the following code :
php myscript.php
%APACHE_HOME%\bin\httpdVendor.exe -k runservice
exit 0
Download/Install the free software BatToExeConverter (next, next, ...)
Open the installed converter and open your freshly created batch file
Click on the button Build EXE (let the default configuration)
Save the file : %APACHE_HOME%\bin\httpd.exe
Start your Apache Server
Tested on : Windows 7, Apache 2.4, Advanced Bat to Exe Converter 2.92
Use built in Windows Task Scheduler which triggers .bat script, which calls curl with defined url.
Download curl from http://curl.haxx.se/download.html and extract curl.exe on any directory, but we will use c:\backgroundtasks
Adjust script below to your needs:
cd c:\
cd c:\backgroundtasks
curl http://localhost/path/to/script.php
exit
Configure Task Scheduler to run as basic task:
General tab - as system account (to run when you are not logged in server)
Triggers tab - adjust frequency
Settings tab - at bottom set If the task is already running... to Stop the existing instance
The best method here would be to use Windows services dependencies.
Make a php-websocket-server.cmd file with any necessary environment settings (e.g. changing to a directory, setting PATH, etc...) with the last line:
php myscript.php
Install the Windows Server Resource Kit Tools, to get srvany and instsrv to create a user defined service. Note the install path as you'll need it in the next step.
Open a cmd shell and run:
<path_to_resource_kit>\instsrv PHPWebSocketServer <path_to_resource_kit>\srvany.exe
Next, create a file php-websocket-server.reg containing the following (update for your environment):
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PHPWebSocketServer\Parameters]
"Application"="c:\\path\\to\\php-websocket-server.cmd"
Import it by double-clicking or regedit /s php-websocket-server.reg
Back in your cmd shell:
sc config Apache2.4 depend= PHPWebSocketServer
to make the Apache2.4* service depend on your php service. Now, when Apache is started, the php service will be brought up first. And likewise, if you stop the php service Apache will stop along with it.
*the howto indicates that the service is named "Apache2.4" but you may want to verify in your installation.
When running as service, you won't have the startup script.
Execute some service implementation that allows running other programs as services, and then make the new service (which is running your script) a dependency of the Apache service. However, this will not restart the script when apache restarts.
One possible solution using SrvStart, and another using ServiceEx.
Perhaps don't install Apache as a service, and then edit the startup/restart script, and use the above method to run Apache as service (instead of using Apache's own installer).
Create bat file,e eg 'myphp.bat' containing path/php myscript.php. Include the correct path to php if it's not path'd.
create a bat file, eg runmyphp.bat containing
AT 00:00 /every:M,T,W,Th,F "cmd /c /path/myphp.bat", again including the correct path.
Then use explorer to drag runmyphp into the startup folder, so it will always run on system startup.
Google 'windows at command' or 'windows cron' to get all the correct syntax for the 'at' command, but you can currently find a detailed explanation here.
I found another answer C:\wamp\scripts\wampserver.lib.php this file is run every time when your wamp starts
include your file path include_once("file_path"); to this file and its done . this is perfect solution which you want
Enjoy!!!!!!!!!
Although the solution of Halayem Anis is very creative, I think its important to note that you can never be sure that a PHP script keeps running in the background. So if you choose to start your script on "Apache start", then you probably end op resetting Apache quite often, simple to reboot your script.
I assume that's even how you came to this question, as on a normal server you never have to touch the Apache reset button. It starts on system start and then it just runs. If that was the case, you could simple run your php myscript.php command on start up.
Considering there is no way to make sure the script keeps running, I would use a different approach, where I check if it is running and if not, restart it.
So the first step is to make it possible to track if the script is running. I would go for the simple approach where your myscript.php writes a single byte to a file every 5seconds or so. This way I can use the last modified time on the file to see if it is still running, because last modified time + 5 seconds < now == not running.
You could also store the last access time in a database every 5 seconds or so. Might be slightly faster then accessing files if you have a lot of traffic.
The second part is to have each request check if the script is running. For this two work I would use the PHP.ini to prepend a php script on every request. You can do it with the auto_append_file option.
This prepend script would work like this:
<?php
$filename = 'checkonline.txt';
$cmd = "php myscript.php";
if (filemtime($filename)+5<time()) {
//run in background without freezing php
//based on code posted on PHP exec manual, linked below
if (substr(php_uname(), 0, 7) == "Windows"){
pclose(popen("start /B ". $cmd, "r"));
}
else {
exec($cmd . " > /dev/null &");
}
}
?>
Make sure to check how filemtime and exec work and what you need to keep in mind. They work slightly different on Windows/*nix.
Wrap-up all your required processes in a batch file and use RunAsService
With some tweaking, you can ensure that your service starts before Apache.

Executing commands in php as root user in arch linux

i am using arch linux. i want to execute the php file which changes the ip of the system. i did
ifconfig eth0 192.168.163.137
in the terminal and it works fine. the same i tried doing with
shell_exec('ifconfig eth0 192.168.163.137');
in a php file and tried opening the page from a remotely located web browser from another pc connected via router. teh page displays nothing and the code also doesnt execute. i guess its the problem with the user executing it.apache is executing it. so i want it to be run by the root.can anyone please guide me to the execution of my code. i even installed sudo and just put
shell_exec('sudo ifconfig......');
it too doesnt execute...please help...thanku..:)
Sudo normally requires an interactive shell to enter your password. That's obviously not going to happen in a PHP script. If you're sure you know what you're doing and you've got your security issues covered, try allowing the Apache user to run sudo without a password, but only for certain commands.
For example, adding the following line in your sudoers file will allow Apache to run sudo without a password, only for the ifconfig command.
apache ALL=NOPASSWD: /sbin/ifconfig
Adjust the path and add any arguments to suit your needs.
Caution:
There might still be complications due to the way PHP calls shell commands.
Remember that it's very risky to allow the web server to run commands as root!
Probably a better alternative:
Write a shell script with the suid bit to make it run as root no matter who calls it.
shell_exec
This function is disabled when PHP is running in safe mode.
Documentation : http://php.net/manual/en/function.shell-exec.php
So, maybe try tweaking your php.ini file?
Write the commands to a queue and have cron pick them up, validate them (only allow known good requests), and run them, then mark that queue complete with the date and result.
Your end-user can then click/wait for update using ajax.

Server side script for launching application

I have been trying unsuccessfully so far to write a php script that will run when a page is opened and that will launch metasploit!
I ve tried shell_exec and exec and all the other alternatives but although I can get it to do simple things (i.e. ls, cds etc) if I try msfconsole it doesnt do anything!
I have also tried a different script that launches firefox and again nothing happens!
Now i know that php runs on the server and I m not expecting to see a console or firefox opening in the clients machine! Instead in order to check if it works I am trying to echo out the output of the shell_exec!But anyway since im hosting the files on my machine (i.e. this is the server and a VM is the client) if it could actually launch firefox i should be able to see the app opening here in the same way as by just doing this from the command line!
What am I missing?
Is there any other way to do this?(i.e. Launch metasploit everytime a user opens up my page)
NOTE: I've tried specifying the full path for msfconsole but that didnt work either!
Heres what I have so far:
$output = shell_exec('/opt/local/libexec/metasploit3/msfconsole;show');
echo "<pre>$output</pre>";
The ";show" bit was used in order to actually make it run something and print some stuff but didnt make any difference!
When you run a gui application from the command prompt in a X window system, it will use the default display. When you run it using php which is embedded in apache webserver, the program may not know where to display the gui application.
there are 2 things to make this work.
The program that executes the gui application must have permission to use display
you need to tell the program which display to use.
I used the following in my php script
<?php
$cmd = `export DISPLAY=:0; gedit`;
shell_exec($cmd);
?>
and ran the script from terminal using php -f test.php
I got the gedit up and running.
You can test the same with the script in apache too.
Please add apache user with privileges to access display server
update: I just added the following in /etc/apache2/apache2.conf (I am using ubuntu)
User poomalai
Group poomalai
and restarted the web server
sudo service apache2 restart
now I accessed localhost/test.php
and Presto!! I got the gedit :)
Hope this helps

Apache and CAP_NET_RAW

I have a php script that carries out a trace route without using system(). It uses SOCK_RAW and ICMP.
I have managed to get this script to run with out been a root user or changing anything in sudoers by using CAP_NET_RAW.
The thing is, the scrip only works when called through the shell, not through the browser. When I go through my browser I get the error: socket_create(): Unable to create socket [1]: Operation not permitted . So something is going a miss here.
After googleing and googleing I am unable to work out why the same script is not working when called through apache. Do I need to add CAP_NET_RAW to an apache config file as well?
Any advice on this would be very much appreciated.
Jason
Typical Apache + PHP installations run under a separate system user (usually www-data). My guess is that this pseudo-user is heavily restricted. Try executing from the shell as the www-data user - it should fail, if I'm right.

Why am I getting a SegFault when I call pdftk from PHP/Apache but not PHP/CLI or directly

When I call /usr/local/bin/pdftk from PHP in Apache (via shell_exec(), exec(), system(), etc.), it returns the SYNOPSIS message as expected.
When I call /usr/local/bin/pdftk input.pdf fill_form input.fdf output output.pdf flatten via shell_exec(), nothing returns.
When I copy and paste the exact same string to the same path in the shell (as the apache user), the output.pdf file is generated as expected.
Moving the pdftk command into a PHP shell script (shebang is #!/usr/bin/php) and executing it with php script.php works perfectly.
Calling that shell script (with its stderr redirected to stdout) from PHP in Apache (via shell_exec(script.php);) results in this line:
sh: line 1: 32547 Segmentation fault /usr/local/bin/pdftk input.pdf fill_form input.fdf output output.pdf flatten 2>&1
Whenever I run the script from the command line (via PHP or directly), it works fine. Whenever I run the script through PHP via Apache, it either fails without any notification or gives the SegFault listed above.
It's PHP 4.3.9 on RHEL4. Please don't shoot me. I've set memory to 512M with ini_set() and made sure that the apache user had read/write to all paths (with fopen()) and by logging in as apache ...
Just went and checked /var/log/messages to find this:
Oct 4 21:17:58 discovery kernel: audit(1286241478.692:1764638):
avc: denied { read } for pid=32627 comm="pdftk" name="zero"
dev=tmpfs ino=2161 scontext=root:system_r:httpd_sys_script_t
tcontext=system_u:object_r:zero_device_t tclass=chr_file
NOTE: Disabling SELinux "fixed" the problem. Has this moved into a ServerFault question? Can anybody give me the 30 second SELinux access controls primer here?
php-cli & php-cgi (or the module, depends on what your server uses) are different binaries. They don't even have to share the same version to live happily side by side on your server. They also may not share the same configuration. Increasing memory usually does nothing to help Segfaults. Points to check:
Are they the same version?
Do they have the same settings (consult the *.ini locations loaded in the phpinfo(); output, and possibly the whole output itself), if not: try what happens if you alter the one for your webserver to the one for the cli as far as possible.
Segfaults occur more in extensions then in the core afaik, and sometimes seemingly unrelated. Try to disable unneeded extensions one by one to see if the problem goes away.
Still no success? You may want to run apache with gdb, but I have no experience with that, it might tell you something though.
No luck? Recompile either the module of cgi your webserver uses.
It's PHP 4.3.9 on RHEL4. Please don't shoot me.
I feel more sad for you then anger, we're beyond the 5.3 mark, come over, it's a lot more happy here.

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