ipaddress module ValueError('%s has host bits set' % self)

Question

I am trying to list valid hosts for given network range via Python3, ipaddress module but I am getting ValueError ValueError('%s has host bits set' % self) while trying to list all valid hosts.

>>> ip_range=input("Enter IP Range:")
Enter IP Range:192.168.56.101/16
>>> list(ipa.ip_network(ip_range).hosts())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.5/ipaddress.py", line 74, in ip_network
    return IPv4Network(address, strict)
  File "/usr/local/lib/python3.5/ipaddress.py", line 1536, in __init__
    raise ValueError('%s has host bits set' % self)
ValueError: 192.168.56.101/16 has host bits set

Answer 1

You have another option. From the document mentioned above, we can see that:

If strict is True and host bits are set in the supplied address, then ValueError is raised. Otherwise, the host bits are masked out to determine the appropriate network address.

So, please try following again.

ip_range = '192.168.56.101/16'
list(ipaddress.ip_network(ip_range, False).hosts())

Answer 2

Two Solutions

Either you change your input or the code.

1: Changing the input

Above you mentioned your input being 192.168.56.101/16. The 16 defines the host bits for this ip-range. Python wants you to clear them (set all those bits to 0). Your specified the ip as 192.168.56.101, while telling there were 16 host bits. Python expected the last 16 bits to be 0.

In binary the Ip looks like this: 11000000.10101000.00111000.01100101. You need to clear the last 16 bits. It then looks like this: 11000000.10101000.0.0 (equal to 192.168.0.0 in decimal).

Concluding: You would need to change your input to 192.168.0.0/16 for it to properly work.

2: Changing the code

Looking at the Python Docs:

If strict is True and host bits are set in the supplied address, then ValueError is raised. Otherwise, the host bits are masked out to determine the appropriate network address.

So deactivate the strict mode by changing your code:

Change ip_network(target) to ip_network(target, False).

Here you could technically input 192.168.56.101/16.

References

• Similar question: python-port-scanner-will-not-accept-address-range
• A tool to convert Ips to binary

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This answer is late, but I believe it is helpful!

Answer 3

As stated in documentation:

A ValueError is raised if address does not represent a valid IPv4 or IPv6 address, or if the network has host bits set.

The number after slash(16 in your case) means, number of bits reserved for subnet, so last 16 bits are your host bits. This method requires those bits as 0 (unset).