Timothy Murphy wrote:
Ljubomir Ljubojevic wrote:
(1) I can open port 22 on the Billion, allowing me to ssh in from outside. But for some reason I cannot ping the same address from outside.
This is due to modem refuses to answer to pings. You might have option to allow it in modem config.
Ping (ICMP) does not use ports but it is packet of type 8.
Thanks again for your response. Could CentOS be preventing me from pinging the system?
Further to my question, how can I determine if it is the Billion 5200S modem/router that is preventing pings, or if it is the CentOS-6 MicroServer attached to the modem/router?
I don't see any reference to ICMP on the modem web-page.
On the other hand the CentOS firewall seems to allow ICMP unless explicitly rejected (which I haven't done).
Surely it would be slightly odd for a modem/router to reject pings by default?
Is there any simple way, short of using something like ethereal, of determining if ICMP packets are reaching the computer, and being rejected there?