deepbreath

  knock_seq=$(cat ~/.ssh/knock_seq)
  let knock_seq++
  echo $knock_seq > ~/.ssh/knock_seq
  concat_seq_secret=$(echo -n "${knock_seq}$(cat ~/.ssh/secret)")
  sha1_output=$(echo -n $concat_seq_secret | sha1sum -b | awk '{print $1}')
  final_output="${sha1_output}${knock_seq}"
  host=localhost
  knocking_port=$(cat ~/.ssh/knocking_port)
  echo -n $final_output | nc -u $host $knocking_port