The router must ensure that IPv6 addresses with IPv4-compatible IPv6 addresses are blocked on both ingress and egress filters.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
SRG-NET-000031-RTR-000033	SRG-NET-000031-RTR-000033	SRG-NET-000031-RTR-000033_rule		Low

Description
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-compatible IPv6 addresses should never appear as a source or destination address. These addresses begin with 0000 and have '0000' in the 16-bit field preceding the IPv4 address. RFC 4291 deprecated the IPv4-compatible addresses.

Description

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-compatible IPv6 addresses should never appear as a source or destination address. These addresses begin with 0000 and have '0000' in the 16-bit field preceding the IPv4 address. RFC 4291 deprecated the IPv4-compatible addresses.

STIG	Date
Router Security Requirements Guide	2013-07-30

Details

Check Text ( C-SRG-NET-000031-RTR-000033_chk )
Review the perimeter router configuration to ensure filters are in place to restrict the IP addresses explicitly, or inexplicitly. Verify that ingress and egress filters for IPv6 have been defined to deny the embedded IPv4-compatible IPv6 addresses and log all violations. If there are not ingress and egress filters configured to deny IPv4-compatible IPv6 addresses and log the violations, this is a finding.

Check Text ( C-SRG-NET-000031-RTR-000033_chk )

Review the perimeter router configuration to ensure filters are in place to restrict the IP addresses explicitly, or inexplicitly. Verify that ingress and egress filters for IPv6 have been defined to deny the embedded IPv4-compatible IPv6 addresses and log all violations. If there are not ingress and egress filters configured to deny IPv4-compatible IPv6 addresses and log the violations, this is a finding.

Fix Text (F-SRG-NET-000031-RTR-000033_fix)
Configure the router filters to restrict IP addresses that contain any embedded IPv4-compatible IPv6 addresses.