# ipv4.bits

Sets how many low-order bits of IPv4 addresses are anonymized.

This parameter applies to IP Address Anonymization Module (mmanon).

Name:

  ipv4.bits

Scope:

  input

Type:

  positive integer

Default:

  input=16

Required?:

  no

Introduced:

  7.3.7

## Description

This sets the number of bits that should be anonymized (bits are from the right, so lower bits are anonymized first). This setting permits to save network information while still anonymizing user-specific data. The more bits you discard, the better the anonymization obviously is. The default of 16 bits reflects what German data privacy rules consider as being sufficiently anonymized. We assume, this can also be used as a rough but conservative guideline for other countries.

Note: when in simple mode, only bits on a byte boundary can be specified. As such, any value other than 8, 16, 24 or 32 is invalid. If an invalid value is given, it is rounded to the next byte boundary (so we favor stronger anonymization in that case). For example, a bit value of 12 will become 16 in simple mode (an error message is also emitted).

## Input usage

    module(load="mmanon")
    action(type="mmanon" ipv4.mode="simple" ipv4.bits="24")

## See also

IP Address Anonymization Module (mmanon)

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