The ping command sends ICMP echo requests to a host and prints replies, latency and loss — the first network check.
ping -c 3 192.0.2.1
three requests and a summary; else Ctrl+C
ping -c 3 -W 1 192.0.2.1
wait at most a second for each reply
ping -c 3 -n 192.0.2.1
no name lookups — faster and cleaner
ping -c 3 -I lab0 192.0.2.1
through a given interface
ping -c 10 -q 192.0.2.1
only the final statistics
ping -c 3 -O 192.0.2.1
report every request left unanswered
ping -4 -c 3 example.com
IPv4 only; -6 for IPv6 only
sudo ip netns exec lab-client ping -c 2 192.0.2.1
from a namespace
ping sends ICMP echo requests to a host and prints each reply.
Without -c it runs until you press Ctrl+C, then prints a summary:
icmp_seq is the request number, time how long the reply took, packet loss the
share of requests without a reply. A reply proves one thing: the packet reached the
host and the reply came back. Whether a website or SSH works on the host, ping
doesn't check — that's done by ports (see ss).
Exit status: 0 — there were replies, 1 — no replies at all, 2 — another error.
Script checks are built on it — and only with -c or -w, otherwise ping never
ends.
Without -c, Linux ping runs forever — unlike Windows, which sends four requests by
default. Full list — man ping.
| Option | What it does | Example |
|---|---|---|
-c count |
Stop after this many requests; without it ping runs forever. | ping -c 3 192.0.2.1 |
-W seconds |
How long to wait for each reply. | ping -c 3 -W 1 192.0.2.1 |
-w seconds |
The overall time limit for ping in seconds. | ping -w 5 192.0.2.1 |
-I interface |
Send through the given interface or from the given address. | ping -c 3 -I lab0 192.0.2.1 |
-n |
No reverse name lookups — numeric output only. | ping -c 3 -n 192.0.2.1 |
-q |
Don't print each reply — only the summary. | ping -c 10 -q 192.0.2.1 |
-O |
Report every request that has no reply yet. | ping -c 3 -O 192.0.2.1 |
-i seconds |
The pause between requests (1 second by default). | ping -c 20 -i 0.5 192.0.2.1 |
-4 |
IPv4 only; -6 for IPv6 only. | ping -4 -c 3 example.com |
-s bytes |
The data size of a request (56 by default). | ping -c 3 -s 1472 -M do 192.0.2.1 |
Nothing found. Try a shorter query.
Network is unreachable is printed at once: the kernel has no route to the address,
and the request never left. Check addresses and routes: ip -br a, ip r (see
ip).
If there is a path but no reply, there are no reply lines at all, and the summary shows
100% packet loss: the requests went out and nothing came back. The host doesn't
exist, is off, or a firewall drops the replies.
A host in your subnet didn't answer ARP — it's missing or off. The line comes from
your machine (From is your address) or a gateway on the way. This is not a timeout:
an error reply did arrive.
The training machine has no network except lo: the client and server live in
network namespaces joined by a veth pair. ping without ip netns exec
looks for the address in the machine's own network and gets Network is unreachable.
There's no route to the address: no address on the interface, an address in another
subnet, or no default route. Check ip -br a and ip r. On the training machine any
outside address answers like this — it's cut off from external networks.
The name didn't turn into an address: no DNS or no network. Try ping by IP address;
if that works, the problem is DNS (see dns-resolv).
A firewall drops ICMP — on the host or on the way. A drop rule gives silence and
loss; reject gives an error line at once, such as Destination Port Unreachable.
Look at the rules: sudo nft list ruleset (see firewall). Check the service itself
by its port — nc -zv host port.
There's no -c: Linux ping keeps sending until you press Ctrl+C. In scripts always
give -c or -w (an overall deadline in seconds).
The path is overloaded or unstable. Send more requests (ping -c 100 -q) and find
which hop loses packets with mtr or tracepath — see network-diagnostics.
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