Brocade Virtual ADX Security Guide (Supporting ADX v03.1.00) - Manual (Page 64)

52 Brocade Virtual ADX Security Guide
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IPv6 ACL overview
3
The following commands apply the ACL rtr to the incoming traffic on ports 2/1 and 2/2.
Default and implicit IPv6 ACL action
The default action when no IPv6 ACLs are configured on an interface is to permit all IPv6 traffic.
However, once you configure an IPv6 ACL and apply it to an interface, the default action for that
interface is to deny all IPv6 traffic that is not explicitly permitted on the interface.
• If you want to tightly control access, configure ACLs consisting of permit entries for the access
you want to permit. The ACLs implicitly deny all other access.
• If you want to secure access in environments with many users, you might want to configure
ACLs that consist of explicit deny entries, then add an entry to permit all access to the end of
each ACL. The permit entry permits packets that are not denied by the deny entries.
Every IPv6 ACL has the following implicit condition as its last match conditions:
deny ipv6 any any – Denies IPv6 traffic. You must enter a permit ipv6 any any as the last
statement in the access-list if you want to permit IPv6 traffic that were not denied by the
previous statements.
NOTE
If an IPv6 ACL has the implicit deny condition, make sure it also permits the IPv6 link-local address,
in addition to the global unicast address. Otherwise, routing protocols such as OSPF will not work.
To view the link-local address, use the show ipv6 interface command.
The conditions are applied in the order shown above, with deny ipv6 any any as the last condition
applied.
For example, if you want to deny ICMP neighbor discovery acknowledgement, then permit any
remaining IPv6 traffic, enter commands such as the following:
The first permit statement permits ICMP traffic from hosts in the 2001:db8:2383:e0bb::x network
to hosts in the 2001:db8:3782::x network.
The deny statement denies ICMP neighbor discovery acknowledgement.
The last entry permits all packets that are not explicitly denied by the other entries. Without this
entry, the ACL will deny all incoming IPv6 traffic on the ports to which you assigned the ACL.
Virtual ADX(config)#sh ipv6 access-list rtr
ipv6 access-list rtr: 3 entries
deny tcp 2001:db8:1570:21::/24 2001:db8:1570:22::/24
deny udp any range 5 6 2001:db8:1570:22::/24
permit ipv6 any any
Virtual ADX(config)#int eth 2/1
Virtual ADX(config-if-2/1)#ipv6 traffic-filter rtr in
Virtual ADX(config-if-2/1)#exit
Virtual ADX(config)#int eth 2/2
Virtual ADX(config-if-2/2)#ipv6 traffic-filter rtr in
Virtual ADX(config)#write memory
Virtual ADX(config)#ipv6 access-list netw
Virtual ADX(config-ipv6-access-list-netw)#permit icmp
2001:db8:2383:e0bb::/64 2001:db8:3782::/64
Virtual ADX(config-ipv6-access-list-netw)#permit ipv6 any any