8.7.4 Packet Tracer – Configure IPv6 ACLs Answers

Packet Tracer – Configure IPv6 ACLs (Answers Version)

Answers Note: Red font color or gray highlights indicate text that appears in the instructor copy only.

Addressing Table

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Objectives

Part 1: Configure, Apply, and Verify an IPv6 ACL

Part 2: Configure, Apply, and Verify a Second IPv6 ACL

Instructions

Part 1:Configure, Apply, and Verify an IPv6 ACL

Logs indicate that a computer on the 2001:db8:1:11::0/64 network is repeatedly refreshing a web page. This is causing a Denial-of-Service (DoS) attack against Server3. Until the client can be identified and cleaned, you must block HTTP and HTTPS access to that network with an access list.

Step 1:Configure an ACL that will block HTTP and HTTPS access.

Configure an ACL named BLOCK_HTTP on R1 with the following statements.

1. Block HTTP and HTTPS traffic from reaching Server3.

R1(config)# ipv6 access-list BLOCK_HTTP

R1(config)# deny tcp any host 2001:db8:1:30::30 eq www

R1(config)# deny tcp any host 2001:db8:1:30::30 eq 443

2. Allow all other IPv6 traffic to pass.

R1(config)# permit ipv6 any any

Step 2:Apply the ACL to the correct interface.

Apply the ACL on the interface closest to the source of the traffic to be blocked.

R1(config)# interface GigabitEthernet0/1

R1(config-if)# ipv6 traffic-filter BLOCK_HTTP in

Step 3:Verify the ACL implementation.

Verify that the ACL is operating as intended by conducting the following tests:

Open the web browser of PC1 to http://2001:db8:1:30::30 or https://2001:db8:1:30::30. The website should appear.

Open the web browser of PC2 to http://2001:db8:1:30::30 or https://2001:db8:1:30::30. The website should be blocked.

Ping from PC2 to 2001:db8:1:30::30. The ping should be successful.

Part 2:Configure, Apply, and Verify a Second IPv6 ACL

The logs now indicate that your server is receiving pings from many different IPv6 addresses in a Distributed Denial of Service (DDoS) attack. You must filter ICMP ping requests to your server.

Step 1:Create an access list to block ICMP.

Configure an ACL named BLOCK_ICMP on R3 with the following statements:

1. Block all ICMP traffic from any hosts to any destination.

R1(config)# ipv6 access-list BLOCK_ICMP

R3(config)# deny icmp any any

2. Allow all other IPv6 traffic to pass.

R3(config)# permit ipv6 any any

Step 2:Apply the ACL to the correct interface.

In this case, ICMP traffic can come from any source. To ensure that ICMP traffic is blocked, regardless of its source or any changes that occur to the network topology, apply the ACL closest to the destination.

R3(config)# interface GigabitEthernet0/0

R3(config-if)# ipv6 traffic-filter BLOCK_ICMP out

Step 3:Verify that the proper access list functions.

1. Ping from PC2 to 2001:db8:1:30::30. The ping should fail.
2. Ping from PC1 to 2001:db8:1:30::30. The ping should fail.
3. Open the web browser of PC1 to http://2001:db8:1:30::30 or https://2001:db8:1:30::30. The website should display.

Answer script

Router R1

enable

config t

ipv6 access-list BLOCK_HTTP

deny tcp any host 2001:db8:1:30::30 eq www

deny tcp any host 2001:db8:1:30::30 eq 443

permit ipv6 any any

interface GigabitEthernet0/1

ipv6 traffic-filter BLOCK_HTTP in

end

Router R3

enable

config t

ipv6 access-list BLOCK_ICMP

deny icmp any any

permit ipv6 any any

interface GigabitEthernet0/0

ipv6 traffic-filter BLOCK_ICMP out

end

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