Test which TCP ports are blocked by my ISP

scan_isp_blocklist.sh

#!/bin/bash

for port in {1..9999}; do
  echo -n "TCP $port: "
  result=$(nc "$1" "$port" -w 1 2>&1 < /dev/null)
  if [ "$?" -eq 0 ]; then
    echo "Open"
    continue
  fi
  if [[ "$result" == *refused* ]]; then
    echo "Closed"
  fi
  if [[ "$result" == *time* ]]; then
    echo "$port" >> block_list.txt
    echo "BLOCKED"
  fi
done

冒昧的问一句，这个脚本如何使用？