IPv6 path outside an IPv4-only filter

How common it is: not established in home parental-control deployments. RFC 9099 documents that improperly controlled IPv6 transition traffic can undermine IPv4 firewall assumptions.

Detection

A destination fails when reached over IPv4 but remains reachable over IPv6; router logs show IPv6 flows not matched by the intended rule.

Fix (technical)

Apply equivalent security policy to IPv4 and IPv6. If a router cannot enforce the intended child policy on IPv6, replace or reconfigure the router rather than silently assuming IPv4 rules cover both s…

Fix (relational)

This is often a configuration defect rather than intentional circumvention. Verify the network before attributing intent.

Residual risk

Transition mechanisms and firmware behavior vary. Disabling IPv6 without understanding the network is not presented as a universal remedy.

Sources

  • rfc9099-ipv6