Add dad-timeout feature for nmcli

[userlerueda]

SUMMARY

Add support for setting IPv4 and IPv6 duplicate address detection (DAD) timeout parameters in the community.general.nmcli module. This enables users to configure NetworkManager's ipv4.dad-timeout and ipv6.dad-timeout settings directly through Ansible, providing better control over network configuration and preventing IP address conflicts in automated environments.

This feature adds two new parameters:

• dad_timeout4: Integer value in milliseconds for IPv4 DAD timeout
• dad_timeout6: Integer value in milliseconds for IPv6 DAD timeout

Fixes #10843

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

nmcli

ADDITIONAL INFORMATION

Background:
Duplicate address detection is a critical network safety feature that prevents IP conflicts. The default DAD timeout is -1 (disabled) for IPv4, leaving networks vulnerable to address conflicts. Currently, users must resort to raw nmcli commands or shell modules to set these parameters, breaking Ansible's idempotency model.

Use Cases:

• Automated server provisioning where static IP assignment must be conflict-free
• Container orchestration platforms requiring guaranteed unique IP addresses
• Network automation in enterprise environments with strict IP management policies
• Recovery scenarios where services must fail-fast on network conflicts

Implementation Details:

• Added dad_timeout4 and dad_timeout6 parameters to module argument specification
• Added corresponding instance variables in the Nmcli class constructor
• Mapped parameters to NetworkManager properties ipv4.dad-timeout and ipv6.dad-timeout
• Added parameters to the integer type validation list
• Updated module documentation with parameter descriptions and usage example
• Created changelog fragment following project conventions

Example Usage:

- name: Configure connection with duplicate address detection
  community.general.nmcli:
    conn_name: ens192
    type: ethernet
    ip4: 192.168.1.100/24
    state: present
    dad_timeout4: 3000  # Enable IPv4 DAD with 3-second timeout
    may_fail4: false

[ansibullbot]

cc @alcamie101
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[felixfontein]

Thanks for your contribution! Please note that you have to adjust the unit tests to avoid the failure. Also please note that this is a new feature, so you should add a small test for it as well to the unit tests. Thanks!

[felixfontein]

Suggested change

	- nmcli - add support for duplicate address detection (DAD) timeout configuration via new parameters ``dad_timeout4`` and ``dad_timeout6`` which map to the ``ipv4.dad-timeout`` and ``ipv6.dad-timeout`` NetworkManager properties (https://github.com/ansible-collections/community.general/pull/XXXX).
	- nmcli - add support for duplicate address detection (DAD) timeout configuration via new parameters ``dad_timeout4`` and ``dad_timeout6`` which map to the ``ipv4.dad-timeout`` and ``ipv6.dad-timeout`` NetworkManager properties (https://github.com/ansible-collections/community.general/issues/10843, https://github.com/ansible-collections/community.general/pull/10844).

[felixfontein]

Suggested change

	version_added: 10.1.0
	version_added: 11.4.0

same below