Mendapatkan ip address

gimana cara mendapatkan ip address dan memasukan ke database ?

public function tambahUser()
	{
		$data = [
			"id" => $this->input->post('id', true),
			"nama" => htmlspecialchars($this->input->post('nama', true)),
			"ip" => $_SERVER["REMOTE_ADDR"]
		];
		$this->db->insert('users', $data);
	}