Ping
We often use the ping
command to check if the host is up. If the host answers, we assume that the host is up and we can interact with it.
If the host doesn't answer, then either it's down, our packets are filtered by a firewall, or it doesn't reply to ICMP requests π.
Refer to the ping documentation for usage.
Rationale
If a host doesn't reply to a ping and we know it's up, we may change our strategy, e.g. adapting our commands. For instance, we may use nmap -Pn [...]
to disable ICMP checks.