SELinux Blocking Ping

[Erik Boyer]

Good Morning,

I have a website written in PHP installed on a 64 bit Fedora 16 server that I am trying to
have ping a host to monitor it's availability.

Because using sockets requires root access I wrote a simple shell script to handle the
ping, returning simply "up" or "down" back to PHP.

The problem is that SELinux seems to be stopping Ping from working correctly. The PHP page
takes a long time to load (around 30 seconds or so) and even if the host is up, the shell
script still reports it as down because of the exit status of ping. In the error log for
PHP there are thousands of lines of:

ping: sendmsg: Permission denied

To the point where if you ping just one host once it grows to over 200 MB. I have tried
Google extensively and it seems others have this problem but there is no real answer. I
have tried setting the setuid and setgid for the ping executable with chmod g+s and u+s,
even giving the apache user ownership permission but to no avail. The only thing that has
worked thus far is to turn off SELinux and then the scripts work fine without issue. I
should also note that I can run the shell script on the shell without a problem, and the
PHP exec() function can run something like "whoami" without issue.

I have looked at the available binary switches for SELinux but none of them seem to do
what I need. I really don't want to have to turn off SELinux for this server, as it is
a webserver and I want as much protection on it as possible.

Does anyone have any suggestions? Any help is appreciated.

Here is the contents of the shell script:

/bin/ping -c 1 -W 0.2 $1
rc=$?
if [[ $rc -eq 0 ]] ; then
        echo "up"
else
        echo "down"
fi

Here is how I am calling this through PHP ($i is predetermined earlier in the script):

$ping = exec("/var/www/html/ips/ping.sh 10.0.1.".$i);
if ($ping == "up")
{
echo "Response time: ";
                echo exec("/usr/bin/perl /var/lib/cacti/scripts/ping.pl
10.0.1.".$i);
                echo " ms.";
}

The perl script is taken from Cacti (installed separately via yum) but does not run from
my scripts with SELinux enabled. Again disabled it returns values as expected, and run
directly from a shell it works without issue.

Could anyone shed some light on this for me?


Thank you,

Erik Boyer
Production / IT System Support

KUKA Toledo Production Operations, LLC

 Tel. [phone], Fax [phone], Cell 419-438-5350
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