I have Ubuntu 14.04 installed and I recently installed the same version from the same CD on my friend's computer. When I try to ping him I don't get any response, when I press Ctrl C to terminate ping it says it sent some number of packets, but none of them were received, 100% packet loss. I thought he might have a firewall installed, but that's unlikely because I just installed his Ubuntu. I read iptables comes with Ubuntu, but if so, why can he ping me and I can't ping him?
The two computers are not connected to a shared network, I'd like to ping him just like I can ping .
1 Answer
A very good way of troubleshooting why pings don't work can be done using traceroute:
traceroute -n <IPaddress>If it is not installed, you can install it using sudo apt-get install traceroute.
From your comments on the question, you ran traceroute and it stopped at a certain IP address and displayed * * * asterisks afterwards, something like this:
traceroute to <IPaddress>, 30 hops max, 60 byte packets 1 1.1.1.1 75.415 ms 75.348 ms 75.298 ms 2 2.2.2.2 28.026 ms 28.025 ms 30.207 ms 3 3.3.3.3 40.006 ms 39.999 ms 45.287 ms 4 4.4.4.4 118.244 ms 90.393 ms 90.350 ms 5 * * * 6 * * * 7 * * * 8 * * *This means that the traceroute got blocked and did not reach the destination. The network device 4.4.4.4 (or the device after it) is the device that is blocking the connection. Since you're going over the internet, I assume that these devices are not controlled by you. This means that you will not be able to ping your friend's IP because something on the internet is blocking it. He can ping you because there's nothing blocking pings originating from his network (that can also include the 4.4.4.4 device that is blocking your pings).
You can double check this by trying to ping his IP address from a different device, a device that is in a different LAN network than you, to verify that probably no one can ping his IP address (and that his ISP is probably blocking it).
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