$ sudo su# telnet 80Trying 0.0.0.80...1. You are using telnet wrong: it should be "telnet [host] [port]". Please read "man telnet".2. You do not need sudo to use telnet, do not do that3. You should also check that Apache is running and listening to this port, use ``ss -lt``.For this command you _may_ use sudo to get process names (``sudo ss -ltp``). Read ``ss --help``If you were able to connect on this host, then try to connect to this machine from outside using public IP