python 正则表达式匹配ip

>>> re.match(r'^(([1-9]|[1-9]d|1dd|2[0-4]d|25[0-5]).){3}([1-9]|[1-9]d|1dd|2[0-4]d|25[0-5])$',"192.168.1.1").group()
'192.168.1.1'