IPv6 PACL (Port ACL)

Lesson Contents

The IPv6 PACL (Port Access Control List) is basically a regular IPv6 access-list that is applied to a switchport (L2 interface). They only work inbound.

Configuration

Let’s look at quick example. Here’s the topology we’ll use:

We will use R1 and R2 to generate some IPv6 traffic and on SW1 we’ll configure the PACL.

Let’s configure some IPv6 addresses on R1 and R2:

R1(config)#interface FastEthernet f0/0
R1(config-if)#ipv6 address 2001:DB8:0:12::1/64

R2(config)#interface FastEthernet 0/0
R2(config-if)#ipv6 address 2001:DB8:0:12::2/64

Let’s enable HTTP server so that we have something to connect to:

R2(config)#ip http server

Without an ACL, I can connect to the telnet server (enabled by default) and the HTTP server:

R1#telnet 2001:DB8:0:12::2
Trying 2001:DB8:0:12::2 ... Open

R1#telnet 2001:DB8:0:12::2 80
Trying 2001:DB8:0:12::2, 80 ... Open

Let’s create an access-list that denies telnet traffic and permits everything else:

SW1(config)#ipv6 access-list NO_TELNET
SW1(config-ipv6-acl)#deny tcp any host 2001:DB8:0:12::2 eq 23
SW1(config-ipv6-acl)#permit ipv6 any any

We can see the access-list we created with the show ipv6 access-list command:

SW1#show ipv6 access-list
IPv6 access list NO_TELNET
    deny tcp any host 2001:DB8:0:12::2  eq telnet sequence 10
    permit ipv6 any any sequence 20

You can also use show access-list without “ipv6” and it will show up.

Let’s activate the access-list on the GigabitEthernet 0/1 interface that connects to R1:

SW1(config)#interface GigabitEthernet 0/1
SW1(config-if)#ipv6 traffic-filter NO_TELNET in

Now, from R1 I’ll try to connect to the telnet and HTTP server on R2:

R1#telnet 2001:DB8:0:12::2
Trying 2001:DB8:0:12::2 ... 
% Connection timed out; remote host not responding

R1#telnet 2001:DB8:0:12::2 80
Trying 2001:DB8:0:12::2, 80 ... Open

As you can see, telnet traffic is no longer permitted.

Unfortunately, hits don’t show in the access-list:

SW1#show ipv6 access-list
IPv6 access list NO_TELNET
    deny tcp any host 2001:DB8:0:12::2  eq telnet sequence 10
    permit ipv6 any any sequence 20

There is the debug ipv6 access-list command but it doesn’t seem to work for PACLs, it only works when you apply an access-list to a routed (L3) interface.

Configurations

Want to take a look for yourself? Here you will find the final configuration of each device.

hostname R1
!
ip cef
!
interface FastEthernet0/0
 ipv6 address 2001:DB8:0:12::1/64
!
end

hostname R2
!
ip cef
!
interface FastEthernet0/0
 ipv6 address 2001:DB8:0:12::2/64
!
ip http server
!
end

SW1

hostname SW1
!
interface GigabitEthernet0/1
 ipv6 traffic-filter NO_TELNET in
!
interface GigabitEthernet0/2
!
ipv6 access-list NO_TELNET
 deny tcp any host 2001:DB8:0:12::2  eq telnet
 permit ipv6 any any
!
end

Conclusion

You have now learned how to configure the IPv6 PACL (Port ACL) on a Cisco switch. I hope you enjoyed this lesson. If you have any questions feel free to leave a comment!