Network — alert on packet loss to an upstream (via mtr)
Connection to a database / partner API loses 5–10 % of packets — the app sees timeouts, but `ping -c 4` says 'all good'. TCP retransmits silently chop throughput.
Recipe
#!/usr/bin/env bash
# /etc/cron.d/packet-loss
# */5 * * * * root /opt/packet-loss.sh
TARGET=${TARGET:-db.internal}
THRESH_PCT=${THRESH_PCT:-3} # alert above 3 % loss
# mtr -r = report mode, -c 100 = 100 packets, -n = numeric only
LOSS=$(mtr -r -c 100 -n "$TARGET" \
| awk 'END {gsub(/%/,"",$3); print $3+0}')
if [ "${LOSS:-0}" -gt "$THRESH_PCT" ]; then
curl -fsS "$HEARTBEAT_URL" --data "loss_pct=$LOSS,target=$TARGET"
exit 2
fi
echo "OK (loss=${LOSS}%)"Same thing in Enterno.io
Use Enterno ping/port instead of your own mtr cron — multi-region monitoring at once, you find geographic issues without standing up your own VPN probes.
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