What it is¶
ping sends ICMP Echo Request packets and reports Echo Reply round-trip times. It's the first tool to reach for when asking "is this host up / reachable / how far away is it" — but it only tells you about ICMP reachability, which is frequently blocked or rate-limited on the actual service ports you care about (see nc/nping for TCP/UDP-level checks).
Basic usage¶
ping example.com # continuous, Ctrl+C to stop
ping -c 5 example.com # stop after 5 packets
ping -c 5 -i 0.2 example.com # 5 packets, 200ms interval (needs root for <200ms)
Reading the output¶
64 bytes from 93.184.216.34: icmp_seq=1 ttl=56 time=14.2 ms
- icmp_seq — sequence number; gaps mean dropped packets
- ttl — remaining hops; a much lower TTL than expected on a LAN host can indicate asymmetric routing or an unexpected extra hop
- time — round-trip time in ms
The summary line at the end (rtt min/avg/max/mdev) gives jitter (mdev — mean deviation) alongside latency, which matters more than raw latency for anything real-time (VoIP, gaming).
Useful flags¶
| Flag | Meaning |
|---|---|
-c <n> |
stop after n packets |
-i <secs> |
interval between packets (root required below 0.2s) |
-s <bytes> |
payload size — useful for MTU/fragmentation testing (see MTU troubleshooting) |
-M do |
set Don't Fragment bit — pairs with -s to find the real path MTU |
-W <secs> |
timeout waiting for a reply |
-4 / -6 |
force IPv4 / IPv6 |
-f |
flood ping (root only) — for load testing, not casual use |
-q |
quiet, summary only |
MTU / fragmentation testing¶
ping -M do -s 1472 example.com # 1472 + 28 bytes overhead = 1500, standard Ethernet MTU
ping -M do -s 8972 -c1 host # jumbo frame test (9000 MTU networks)
If a size fails with "Message too long" but a smaller one succeeds, you've found the actual path MTU — see the MTU troubleshooting guide for the full binary-search workflow.
IPv6¶
ping6 example.com # or: ping -6 example.com (modern iputils merged the binaries)
Cheat sheet¶
ping -c 5 host # quick reachability check, 5 packets
ping -c 5 -i 0.2 host # faster interval
ping -M do -s 1472 host # MTU probe (standard Ethernet)
ping6 host # IPv6