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11.6.2 Lab - Switch Security Configuration

Topology

Addressing Table

Device	Interface / VLAN	IP Address	Subnet Mask
R1	G0/0/1	192.168.10.1	255.255.255.0
R1	Loopback 0	10.10.1.1	255.255.255.0
S1	VLAN 10	192.168.10.201	255.255.255.0
S2	VLAN 10	192.168.10.202	255.255.255.0
PC – A	NIC	DHCP	255.255.255.0
PC – B	NIC	DHCP	255.255.255.0

Objectives

Part 1: Configure the Network Devices.

• Cable the network.
• Configure R1.
• Configure and verify basic switch settings.

Part 2: Configure VLANs on Switches.

• Configure VLAN 10.
• Configure the SVI for VLAN 10.
• Configure VLAN 333 with the name Native on S1 and S2.
• Configure VLAN 999 with the name ParkingLot on S1 and S2.

Part 3: Configure Switch Security.

• Implement 802.1Q trunking.
• Configure access ports.
• Secure and disable unused switchports.
• Document and implement port security features.
• Implement DHCP snooping security.
• Implement PortFast and BPDU guard.
• Verify end-to-end-connectivity.

Background / Scenario

This is a comprehensive lab to review previously covered Layer 2 security features.

Note: The routers used with CCNA hands-on labs are Cisco 4221 with Cisco IOS XE Release 16.9.3

(universalk9 image). The switches used in the labs are Cisco Catalyst 2960s with Cisco IOS Release 15.0(2) (lanbasek9 image). Other routers, switches, and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and the output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of the lab for the correct interface identifiers.

Note: Make sure that the switches have been erased and have no startup configurations. If you are unsure, contact your instructor.

Required Resources

• 1 Router (Cisco 4221 with Cisco IOS XE Release 16.9.3 universal image or comparable)
• 2 Switches (Cisco 2960 with Cisco IOS Release 15.0(2) lanbasek9 image or comparable)
• 2 PCs (Windows with a terminal emulation program, such as Tera Term)
• Console cables to configure the Cisco IOS devices via the console ports
• Ethernet cables as shown in the topology Instructions

Part 1: Configure the Network Devices.

Step 1: Cable the network.

1. Cable the network as shown in the topology.
2. Initialize the devices.

Step 2: Configure R1.

a. Load the following configuration script on R1.

Open configuration window

enable configure terminal hostname R1 no ip domain lookup ip dhcp excluded-address 192.168.10.1 192.168.10.9 ip dhcp excluded-address 192.168.10.201 192.168.10.202 ! ip dhcp pool Students  network 192.168.10.0 255.255.255.0  default-router 192.168.10.1  domain-name CCNA2.Lab-11.6.1 ! interface Loopback0  ip address 10.10.1.1 255.255.255.0 !

interface GigabitEthernet0/0/1  description Link to S1 Port 5  ip dhcp relay information trusted  ip address 192.168.10.1 255.255.255.0  no shutdown !

line con 0  logging synchronous  exec-timeout 0 0

2. Verify the running-configuration on R1 using the following command:

R1# show ip interface brief

3. Verify IP addressing and interfaces are in an up / up state (troubleshoot as necessary).

Close configuration window

Step 3: Configure and verify basic switch settings.

1. Configure the hostname for switches S1 and S2.

Open configuration window

Open configuration window

2. Prevent unwanted DNS lookups on both switches.
3. Configure interface descriptions for the ports that are in use in S1 and S2.
4. Set the default-gateway for the Management VLAN to 192.168.10.1 on both switches.

Part 2: Configure VLANs on Switches.

Step 1: Configure VLAN 10.

Add VLAN 10 to S1 and S2 and name the VLAN Management.

Step 2: Configure the SVI for VLAN 10.

Configure the IP address according to the Addressing Table for SVI for VLAN 10 on S1 and S2. Enable the SVI interfaces and provide a description for the interface.

Step 3: Configure VLAN 333 with the name Native on S1 and S2.

Step 4: Configure VLAN 999 with the name ParkingLot on S1 and S2.

Part 3: Configure Switch Security.

Step 1: Implement 802.1Q trunking.

1. On both switches, configure trunking on F0/1 to use VLAN 333 as the native VLAN.
2. Verify that trunking is configured on both switches.

S1# show interface trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Fa0/1       on               802.1q         trunking      333

 

Port        Vlans allowed on trunk

Fa0/1       1-4094

 

Port        Vlans allowed and active in management domain

Fa0/1       1,10,333,999

 

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/1       1,10,333,999

 

S2# show interface trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Fa0/1       on               802.1q         trunking      333

 

Port        Vlans allowed on trunk

Fa0/1       1-4094

 

Port        Vlans allowed and active in management domain

Fa0/1       1,10,333,999

 

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/1       1,10,333,999

3. Disable DTP negotiation on F0/1 on S1 and S2. 
4. Verify with the show interfaces command.

S1# show interfaces f0/1 switchport | include Negotiation

Negotiation of Trunking: Off

 

S2# show interfaces f0/1 switchport | include Negotiation Negotiation of Trunking: Off Step 2: Configure access ports.

1. On S1, configure F0/5 and F0/6 as access ports that are associated with VLAN 10.
2. On S2, configure F0/18 as an access port that is associated with VLAN 10.

Step 3: Secure and disable unused switchports.

1. On S1 and S2, move the unused ports from VLAN 1 to VLAN 999 and disable the unused ports.
2. Verify that unused ports are disabled and associated with VLAN 999 by issuing the show command.

S1# show interfaces status

 

Port      Name               Status       Vlan       Duplex  Speed Type

Fa0/1     Link to S2         connected    trunk      a-full  a-100 10/100BaseTX

Fa0/2                        disabled     999          auto   auto 10/100BaseTX

Fa0/3                        disabled     999          auto   auto 10/100BaseTX

Fa0/4                        disabled     999          auto   auto 10/100BaseTX

Fa0/5     Link to R1         connected    10         a-full  a-100 10/100BaseTX

Fa0/6     Link to PC-A       connected    10         a-full  a-100 10/100BaseTX

Fa0/7                        disabled     999          auto   auto 10/100BaseTX

Fa0/8                        disabled     999          auto   auto 10/100BaseTX

Fa0/9                        disabled     999          auto   auto 10/100BaseTX Fa0/10                       disabled     999          auto   auto 10/100BaseTX

<output omitted>

S2# show interfaces status

 

Port      Name               Status       Vlan       Duplex  Speed Type

Fa0/1     Link to S1         connected    trunk      a-full  a-100 10/100BaseTX

Fa0/2                        disabled     999          auto   auto 10/100BaseTX Fa0/3                        disabled     999          auto   auto 10/100BaseTX <output omitted>

Fa0/14                       disabled     999          auto   auto 10/100BaseTX

Fa0/15                       disabled     999          auto   auto 10/100BaseTX

Fa0/16                       disabled     999          auto   auto 10/100BaseTX

Fa0/17                       disabled     999          auto   auto 10/100BaseTX

Fa0/18    Link to PC-B       connected    10         a-full  a-100 10/100BaseTX

Fa0/19                       disabled     999          auto   auto 10/100BaseTX

Fa0/20                       disabled     999          auto   auto 10/100BaseTX

Fa0/21                       disabled     999          auto   auto 10/100BaseTX

Fa0/22                       disabled     999          auto   auto 10/100BaseTX

Fa0/23                       disabled     999          auto   auto 10/100BaseTX

Fa0/24                       disabled     999          auto   auto 10/100BaseTX Gi0/1                        disabled     999          auto   auto 10/100/1000BaseTX

Gi0/2                        disabled     999          auto   auto 10/100/1000BaseTX Step 4: Document and implement port security features.

The interfaces F0/6 on S1 and F0/18 on S2 are configured as access ports. In this step, you will also configure port security on these two access ports.

1. On S1, issue the show port-security interface f0/6 command to display the default port security settings for interface F0/6. Record your answers in the table below.

Default Port Security Configuration
Feature	Default Setting
Port Security
Maximum number of MAC addresses
Violation Mode
Aging Time
Aging Type
Secure Static Address Aging
Sticky MAC Address

2. On S1, enable port security on F0/6 with the following settings:

o Maximum number of MAC addresses: 3 o Violation type: restrict o Aging time: 60 min o Aging type: inactivity

c. Verify port security on S1 F0/6.

S1# show port-security interface f0/6

Port Security              : Enabled

Port Status                : Secure-up

Violation Mode             : Restrict

Aging Time                 : 60 mins

Aging Type                 : Inactivity

SecureStatic Address Aging : Disabled

Maximum MAC Addresses      : 3

Total MAC Addresses        : 1

Configured MAC Addresses   : 0

Sticky MAC Addresses       : 0

Last Source Address:Vlan   : 0022.5646.3411:10

Security Violation Count   : 0

 

S1# show port-security address

               Secure Mac Address Table

-----------------------------------------------------------------------------

Vlan    Mac Address       Type                          Ports   Remaining Age

                                                                   (mins)

----    -----------       ----                          -----   -------------   10    0022.5646.3411    SecureDynamic                 Fa0/6       60 (I)

-----------------------------------------------------------------------------

Total Addresses in System (excluding one mac per port)     : 0

Max Addresses limit in System (excluding one mac per port) : 8192

4. Enable port security for F0/18 on S2. Configure the port to add MAC addresses learned on the port automatically to the running configuration.
5. Configure the following port security settings on S2 F/18:

o Maximum number of MAC addresses: 2 o Violation type: Protect o Aging time: 60 min

6. Verify port security on S2 F0/18.

S2# show port-security interface f0/18

Port Security              : Enabled

Port Status                : Secure-up

Violation Mode             : Protect

Aging Time                 : 60 mins

Aging Type                 : Absolute

SecureStatic Address Aging : Disabled

Maximum MAC Addresses      : 2

Total MAC Addresses        : 1

Configured MAC Addresses   : 0

Sticky MAC Addresses       : 0

Last Source Address:Vlan   : 0022.5646.3413:10

Security Violation Count   : 0

 

S2# show port-security address

               Secure Mac Address Table

-----------------------------------------------------------------------------

Vlan    Mac Address       Type                          Ports   Remaining Age                                                                    (mins)

----    -----------       ----                          -----   -------------   10    0022.5646.3413    SecureSticky                  Fa0/18       -

-----------------------------------------------------------------------------

Total Addresses in System (excluding one mac per port)     : 0

Max Addresses limit in System (excluding one mac per port) : 8192 Step 5: Implement DHCP snooping security.

1. On S2, enable DHCP snooping and configure DHCP snooping on VLAN 10.
2. Configure the trunk port on S2 as a trusted port.
3. Limit the untrusted port, F18 on S2, to five DHCP packets per second.
4. Verify DHCP Snooping on S2.

S2# show ip dhcp snooping

Switch DHCP snooping is enabled

DHCP snooping is configured on following VLANs:

10

DHCP snooping is operational on following VLANs:

10

DHCP snooping is configured on the following L3 Interfaces: Insertion of option 82 is enabled    circuit-id default format: vlan-mod-port    remote-id: 0cd9.96d2.3f80 (MAC) Option 82 on untrusted port is not allowed

Verification of hwaddr field is enabled

Verification of giaddr field is enabled

DHCP snooping trust/rate is configured on the following Interfaces:

 

Interface                  Trusted    Allow option    Rate limit (pps)

-----------------------    -------    ------------    ---------------- FastEthernet0/1            yes        yes             unlimited   Custom circuit-ids:

FastEthernet0/18           no         no              5   Custom circuit-ids:

5. From the command prompt on PC-B, release and then renew the IP address.

C:\Users\Student> ipconfig /release

C:\Users\Student> ipconfig /renew

6. Verify the DHCP snooping binding using the show ip dhcp snooping binding command.

S2# show ip dhcp snooping binding

MacAddress          IpAddress        Lease(sec)  Type           VLAN  Interface

------------------  ---------------  ----------  -------------  ----  -------------------

00:50:56:90:D0:8E   192.168.10.11    86213       dhcp-snooping   10   FastEthernet0/18 Total number of bindings: 1

Step 6: Implement PortFast and BPDU guard.

1. Configure PortFast on all the access ports that are in use on both switches.
2. Enable BPDU guard on S1 and S2 VLAN 10 access ports connected to PC-A and PC-B.
3. Verify that BPDU guard and PortFast are enabled on the appropriate ports.

S1# show spanning-tree interface f0/6 detail

 Port 8 (FastEthernet0/6) of VLAN0010 is designated forwarding    Port path cost 19, Port priority 128, Port Identifier 128.6.

   <output omitted for brevity>

   Number of transitions to forwarding state: 1

   The port is in the portfast mode

   Link type is point-to-point by default

   Bpdu guard is enabled

   BPDU: sent 128, received 0

Step 7: Verify end-to-end connectivity.

Verify PING connectivity between all devices in the IP Addressing Table. If the pings fail, you may need to disable the firewall on the PC hosts.

Close configuration window

Reflection Questions

1. In reference to Port Security on S2, why is there no timer value for the remaining age in minutes when sticky learning was configured?

Type your answers here.

2. In reference to Port Security on S2, if you load the running-config script on S2, why will PC-B on port 18 never get an IP address via DHCP?

Type your answers here.

3. In reference to Port Security, what is the difference between the absolute aging type and inactivity aging type?

Type your answers here.

End of Document