regular expression for ipaddress and mac address

Question

can anyone suggest me the regular expression for ip address and mac address ?

i am using python & django

for example , http://[ipaddress]/SaveData/127.0.

Answer 1

consider s=256.1.1.1 i'd like to make a little modification from Michal's answer:

def find_ip(s):
    part = '(2[0-4]|1[0-9]|[0-9])?[0-9]|25[0-5]'
    res =re.search(r'(^| )((%s)\.){3}(%s)' %(part,part), s,re.I )
    if res:
        return res.group().strip()
    else:
        return ''

notice '(^| )' means line start or space ahead, to avoid get '56.1.1.1' from '256.1.1.1'