Ping IP returned “destination net unreachable”, even with different network

internetping

I couldn't log in to facebook, so I ping the domain and got this:

ping www.facebook.com

Pinging www.facebook.com [69.171.228.14] with 32 bytes of data:

Request timed out.

Reply from 204.15.23.57: Destination net unreachable.

But when I ping this IP, it is reachable.

Pinging 204.15.23.57 with 32 bytes of data:

Reply from 204.15.23.57: bytes=32 time=190ms TTL=51

I realize it is something wrong with my computer, as I have tried using different networks (on the same network other devices can connect to facebook), resetting router's routing table, clear my computer arp cache…but none of it works.

Does anyone have any idea?

Best Answer

What your commands show is the following:

  1. Your computer has resolved www.facebook.com address to be 69.171.228.14
  2. It is trying to send ping packets to it
  3. On the packet's way a router (possibly your's, at address 204.15.23.57) cannot find route to 69.171.228.14
  4. So that you know about this the router 204.15.23.57 is informing you about this with the ICMP reply message Destination net unreachable.

In your second command you are pinging the router who gave you net unreachable reply, not facebook host, therefore unsurprisingly you get a reply from it.

As you have helpfully pointed out - this was result from a messed-up hosts file. You also could have seen the problem if you had used nslookup to query a DNS server directly:

nslookup
server 8.8.4.4
www.facebook.com

This would have shown you the actual address of the facebook host and you would have noticed that it is different from the one given to you (69.171.228.14 ), so you would have known to look in the hosts file as a computer resolves IP addresses through hosts file or DNS queries.

Having said that it is not good that a virus has been able to update the hosts file, since that should only be writable by a superuser/system (Administrator, SYSTEM or root on Linux). Therefore the implication is that the virus/trojan had high level access to the system.

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