NET-IPV6-031 - Embedded IPv4-Mapped IPv6 ADDR are not blocked - 'deny ipv6 any 0::FFFF/96 log'

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Information

The IAO/NSO will ensure that IPv6 addresses with embedded IPv4-mapped IPv6 addresses are blocked on the ingress and egress filters, (0--FFFF/96).

The IPv6 transition mechanisms include a technique for hosts and routers to dynamically tunnel IPv6 packets over IPv4 routing infrastructure. IPv6 nodes that use this technique are assigned special IPv6 unicast addresses that carry a global IPv4 address in the low-order 32 bits. IPv4-mapped IPv6 addresses should never appear as a source or destination address. These addresses begin with 0000 and have 'FFFF' in the 16 bit field preceding the IPv4 address. There is little use for the IPv4-mapped addresses and there has been some confusion for what their intended use was. There were three revisions of IPv6 Basic API specification (RFC 2133, 2553, and 3493). Under the current usage of the API, no packets should appear on the wire with these addresses so blocking them is the policy.

NOTE: Change 'IPV6_INGRESS_ACL' to the access control list for IPv6 inbound connection filtering.

Solution

The administrator will configure the router ACLs to restrict IP addresses that contain any embedded IPv4-mapped IPv6 addresses.

See Also

https://iasecontent.disa.mil/stigs/zip/U_Network_Perimeter_Router_L3_Switch_V8R32_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7, CAT|II, Rule-ID|SV-15413r1_rule, STIG-ID|NET-IPV6-031, Vuln-ID|V-14699

Plugin: Cisco

Control ID: cfa567859272baf03faf9bf5b65c21702b0edd511dec2384a12c3df3ced6dc89