PHP developers usually use Curl to connect to the external network, but it could fail on Linux due to permission issue. For example, a PHP code snippet like this:
<?php
$title = urlencode("Ricky Martin");
$url = "http://en.wikipedia.org/w/api.php?format=json&action=query&titles=$title&prop=revisions&rvprop=content";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
curl_setopt($ch, CURLOPT_USERAGENT, 'Example/1.0 (http://www.example.com/)');
$result = curl_exec($ch);
if (!$result) {
echo curl_error($ch);
} else {
var_dump($result);
}
?>The above example was trying to connect to wikipedia, but Curl failed with the following error:
It seems Curl was trying to resolve the domain name did not have the ability to do it. My first guess is that it's a permission issue of httpd.
Let's check SELinux boolean value of httpd
[root@www ~]# getsebool -a | grep httpd
...
httpd_can_network_connect --> off
...There is a suspect permission called httpd_can_network_connect in the list, which could be the key to the problem.
Let's enable the permission.
[root@www ~]# setsebool -P httpd_can_network_connect on
[root@www ~]# getsebool -a | grep httpd
...
httpd_can_network_connect --> on
...Don't forget to restart httpd after enabling.
[root@web ~]# service httpd restart
Stopping httpd: [ OK ]
Starting httpd: [ OK ]Then, try the PHP code again, it's back to normal.
If you have already enabled httpd_can_network_connect, restarting httpd service could be helpful.