21.2.2 Packet Tracer – Configure IPv6 ACLs (Answers)
Topology
21.2.2 Packet Tracer – Configure IPv6 ACLs
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Addressing Table
| Device | Interface | IPv6 Address/Prefix | Default Gateway |
|---|---|---|---|
| Server3 | NIC | 2001:DB8:1:30::30/64 | FE80::30 |
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 a Denial-of-Service (DoS) attack against Server3. Until the client can be identified and investigated, you must block HTTP and HTTPS access to that network with an IPv6 access control 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.
a. Block HTTP and HTTPS traffic from reaching Server3.
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
b. 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:
a. Block all ICMP traffic from any hosts to any destination.
R3(config)# deny icmp any any
b. 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.
a. Ping from PC2 to 2001:DB8:1:30::30. The ping should fail.
b. Ping from PC1 to 2001:DB8:1:30::30. The ping should fail.
c. Open the web browser of PC1 to http://2001:DB8:1:30::30 or https://2001:DB8:1:30::30. The website should display.
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