On 6/6/07, David Whelan wrote:
what happens when you enter the ping command: the chain of processes, what they do, and how to find out if they were successful, and what goes out and what comes into the box. Because ping requires so many other processes to work, this might be a useful way to troubleshoot a connectivity problem like mine.
If you want to see exactly what ping is doing, run 'strace ping IPADDRESS'. To see what "goes out and what comes into the box," use tcpdump. The output of both of these commands may be difficult to decipher. If you can't communicate with any host on the Internet, you probably have a problem that ping by itself can't solve. You will need to check your DNS, routing/gateway, and physical network connections.