Read TCP Protocol Statistics with netstat -s -p tcp

01Command

$ netstat -s -p tcp
# Just the interesting lines:
netstat -s -p tcp | grep -Ei "retransmit|out-of-order|listen queue"

02What it does

`netstat -s` prints the kernel's accumulated protocol statistics, and `-p tcp` narrows it to the TCP block: packets sent/received, retransmit timeouts, out-of-order deliveries, and — importantly — listen queue overflows that mean an app is too slow to accept connections. Unlike a speed test, these counters show *why* a link feels slow without generating any traffic. Take two snapshots a minute apart and diff them to measure ongoing loss.

03Risk

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

• netstat — macOS Command Reference
  SS64 · technical · 2026-09-17
  Evidence: Documents the -s (statistics) and -p <protocol> flags.

Last verified: 2026-09-17 · Category: Network

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