CODEWITHSUNDEEP
pythonpython-2.7
Damon
Damon

Reputation: 89

Finding and converting subnet mask to CIDR in a list

I have a list containing hundreds of ip addresses and masks in this format:

['10.10.10.0/255.255.255.0', '10.10.20.0/255.255.255.192']

I would like to convert this list to this format:

['10.10.10.0/24', '10.10.20.0/26']

Here is my code:

# List already containing all ip/mask (format: 10.10.10.0/255.255.255.0') shown above
print ip_mask_list
#hardcoded mask for testing
netmask = "255.255.248.0"
#convert mask to CIDR
cidr = sum([bin(int(x)).count('1') for x in netmask.split('.')])
print cidr  # prints 21

I can convert a mask to CIDR but how would I do it so instead of passing hardcoded netmask variable, I can pass ip_mask_list and it goes thru all masks and convert the to CIDR as shown above. Maybe create a next list where all 255.x.x.x are converted to /xx.

Thanks

Damon

Upvotes: 0

Views: 2261

Answers (2)

0x51ba
0x51ba

Reputation: 463

This one splits the original IP address in an IP and a mask part. The IP Address is used as before while the cidr_suffix is calculated based on the number of set bits in the ip_mask. 

ips = ['10.10.10.0/255.255.255.0', '10.10.20.0/255.255.255.192']

def append_cidr_suffix(full_ip):
    address_and_mask = full_ip.split('/')
    prefix = address_and_mask[0]
    ip_mask = address_and_mask[1]

    suffix = sum(bin(int(sub_part)).count('1') for sub_part in ip_mask.split('.'))   

    return prefix + '/' + str(suffix)

cidr_ips = [append_cidr_suffix(i) for i in ips]

Upvotes: 0

Ajax1234
Ajax1234

Reputation: 71451

You can use regex:

import re
s = ['10.10.10.0/255.255.255.0', '10.10.20.0/255.255.255.192']
final_ips = ['{}/{}'.format(a, sum([bin(int(x)).count('1') for x in b.split('.')])) for a, b in map(lambda x:re.findall('[\d\.]+', x), s)]

Output:

['10.10.10.0/24', '10.10.20.0/26']

Upvotes: 1

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