Using a RegEx to match IP addresses in Python

Question

I\'m trying to make a test for checking whether a sys.argv input matches the RegEx for an IP address...

As a simple test, I have the following...

imp         


        

Answer 1

If you really want to use RegExs, the following code may filter the non-valid ip addresses in a file, no matter the organiqation of the file, one or more per line, even if there are more text (concept itself of RegExs) :

def getIps(filename):
    ips = []
    with open(filename) as file:
        for line in file:
            ipFound = re.compile("^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$").findall(line)
            hasIncorrectBytes = False
            try:
                    for ipAddr in ipFound:
                        for byte in ipAddr:
                            if int(byte) not in range(1, 255):
                                hasIncorrectBytes = True
                                break
                            else:
                                pass
                    if not hasIncorrectBytes:
                        ips.append(ipAddr)
            except:
                hasIncorrectBytes = True

    return ips

Answer 2

def ipcheck():
# 1.Validate the ip adderess
input_ip = input('Enter the ip:')
flag = 0

pattern = "^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$"
match = re.match(pattern, input_ip)
if (match):
    field = input_ip.split(".")
    for i in range(0, len(field)):
        if (int(field[i]) < 256):
            flag += 1
        else:
            flag = 0
if (flag == 4):
    print("valid ip")
else:
    print('No match for ip or not a valid ip')

Answer 3

IP address uses following authentication :

1. 255 ---> 250-255
2. 249 ---> 200-249
3. 199 ---> 100-199
4. 99 ---> 10-99

5. 9 ---> 1-9

   import re    
   k = 0
   while k < 5 : 
       i = input("\nEnter Ip address : ")
       ip = re.match("^([1][0-9][0-9].|^[2][5][0-5].|^[2][0-4][0-9].|^[1][0-9][0-9].|^[0-9][0-9].|^[0-9].)([1][0-9][0-9].|[2][5][0-5].|[2][0-4][0-9].|[1][0-9][0-9].|[0-9][0-9].|[0-9].)([1][0-9][0-9].|[2][5][0-5].|[2][0-4][0-9].|[1][0-9][0-9].|[0-9][0-9].|[0-9].)([1][0-9][0-9]|[2][5][0-5]|[2][0-4][0-9]|[1][0-9][0-9]|[0-9][0-9]|[0-9])$",i)
       k = k + 1 
       if ip:
           print ("\n=====================")
           print ("Valid IP address")
           print ("=====================")
           break
       else :
           print ("\nInvalid IP")
   else :
       print ("\nAllowed Max 5 times")
   

Reply me if you have doubt?

Answer 4

import re
ipv=raw_input("Enter an ip address")
a=ipv.split('.')
s=str(bin(int(a[0]))+bin(int(a[1]))+bin(int(a[2]))+bin(int(a[3])))
s=s.replace("0b",".")
m=re.search('\.[0,1]{1,8}\.[0,1]{1,8}\.[0,1]{1,8}\.[0,1]{1,8}$',s)
if m is not None:
    print "Valid sequence of input"
else :
    print "Invalid input sequence"

Just to keep it simple I have used this approach. Simple as in to explain how really ipv4 address is evaluated. Checking whether its a binary number is although not required. Hope you like this.

Answer 5

You are trying to use . as a . not as the wildcard for any character. Use \. instead to indicate a period.

Answer 6

Using regex to validate IP address is a bad idea - this will pass 999.999.999.999 as valid. Try this approach using socket instead - much better validation and just as easy, if not easier to do.

import socket

def valid_ip(address):
    try: 
        socket.inet_aton(address)
        return True
    except:
        return False

print valid_ip('10.10.20.30')
print valid_ip('999.10.20.30')
print valid_ip('gibberish')

If you really want to use parse-the-host approach instead, this code will do it exactly:

def valid_ip(address):
    try:
        host_bytes = address.split('.')
        valid = [int(b) for b in host_bytes]
        valid = [b for b in valid if b >= 0 and b<=255]
        return len(host_bytes) == 4 and len(valid) == 4
    except:
        return False