Is there a command to ping via PHP?

I know you can connect to ports etc but is there a command to ping.

If not is there a port which is open on all servers and always up when the server is up?

port 80 for example... but that goes down when http goes down and due to that it can cause fake downtime as such at times of high load when server lags...

use the exec function..

and just make the system do "ping ip"

parse the data which is returned, and display it.

there are many security issues with exec function and as such id rather not use it. Is there any other way...

http://pear.php.net/package/Net_Ping

Thank you Matt, Ill take a look later

Net_Ping still just executes the ping command. Generating ICMP packets requires root access (ping is suid root), which is why there's no native version.

Connecting to a port that is not in use should (firewalls permitting) generate a Connection Refused response. You could time that to get your ping.