Lab Simulation 54 Please use the "Tasks" and "Topology" tabs to complete this lablet. Topology Tasks Connectivity between the devices has been established. IP services must be configured to complete t

Question

Exhibits

Explanation

This lab simulation requires configuring NAT PAT on Router R2, setting up Router R3 as an NTP client using R2, completing DHCP configurations across R2 (server), Sw1 (relay), and R3 (client), and removing specific SSH configurations from R2.

Approach. The correct approach involves a series of CLI commands on specific devices, based on the task requirements and network topology:

Task 1: Router R2 PAT Configuration

• Interaction: Access the command-line interface (CLI) of Router R2.
• Commands:

  enable
  configure terminal
  interface ethernet0/1
   ip nat inside
  exit
  interface ethernet0/0
   ip nat outside
  exit
  access-list 1 permit 10.0.122.1
  ip nat inside source list 1 interface ethernet0/0 overload
  end
  copy running-config startup-config
  

• Reasoning:
  • interface ethernet0/1; ip nat inside: Designates the interface connecting to the private network (where Sw1's 10.0.122.1 resides) as the NAT inside interface.
  • interface ethernet0/0; ip nat outside: Designates the interface connecting to the public network (ISP) as the NAT outside interface.
  • access-list 1 permit 10.0.122.1: Defines an access list to match the private IP address of Sw1's e0/0 interface (10.0.122.1).
  • ip nat inside source list 1 interface ethernet0/0 overload: Configures Port Address Translation (PAT). It translates traffic from 10.0.122.1, using the IP address of R2's Ethernet0/0 interface (209.165.201.2) as the public source, and uses overload to allow multiple private connections to share this single public IP via port multiplexing. This directly fulfills the requirement to use the IP address of Ethernet0/0.
• Verification (Conceptual): From Sw1, ping 209.165.200.224 source 10.0.122.1. On R2, show ip nat translations to confirm the translation entry.

Task 2: Router R3 NTP Client

• Interaction: Access the CLI of Router R3.
• Commands:

  enable
  configure terminal
  ntp server 10.0.122.2
  end
  copy running-config startup-config
  

• Reasoning:
  • ntp server 10.0.122.2: Configures R3 to synchronize its clock with an NTP server. R2's Ethernet0/1 interface (10.0.122.2) serves as the NTP server, which is reachable from R3 through Sw1 (assuming 'Connectivity between the devices has been established' includes basic routing). This adheres to the constraint of not using broadcast commands.
• Verification (Conceptual): On R3, show ntp status and show clock detail to check synchronization status.

Task 3: Complete the DHCP configuration

• Interaction: Access the CLI of Router R2, Switch Sw1, and Router R3.
• Commands: On R2 (DHCP Server - completing partial configuration for VLAN 220 clients):

  enable
  configure terminal
  ip dhcp pool VLAN220_POOL
   network 10.220.10.0 255.255.255.0
   default-router 10.220.10.1
  exit
  ip dhcp excluded-address 10.220.10.1
  end
  copy running-config startup-config
  

  On Sw1 (DHCP Relay - assuming Sw1 is a Layer 3 switch and acts as the gateway for VLAN 220):

  enable
  configure terminal
  vlan 220
  exit
  interface ethernet0/1
   switchport mode access
   switchport access vlan 220
  exit
  interface vlan 220
   ip address 10.220.10.1 255.255.255.0
   ip helper-address 10.0.122.2
  exit
  ip routing
  end
  copy running-config startup-config
  

  On R3 (DHCP Client):

  enable
  configure terminal
  interface ethernet0/0
   ip address dhcp
   no shutdown
  exit
  end
  copy running-config startup-config
  

• Reasoning:
  • R2: Defines a DHCP pool VLAN220_POOL for the 10.220.10.0/24 network, including the default-router (Sw1's SVI for VLAN 220) and excluding the gateway IP from assignment. This completes R2's role as a DHCP server.
  • Sw1: Creates VLAN 220, assigns Ethernet0/1 to it as an access port (connecting to R3). The interface vlan 220 (SVI) is configured with 10.220.10.1 as its IP (acting as the default gateway for clients) and ip helper-address 10.0.122.2 to forward DHCP broadcasts from VLAN 220 clients to R2's DHCP server. ip routing enables L3 forwarding on Sw1.
  • R3: ip address dhcp configures R3's Ethernet0/0 interface to obtain its IP address and network configuration dynamically from the DHCP server (R2 via Sw1's relay).
• Verification (Conceptual): On R3, show ip interface brief to confirm e0/0 receives an IP from 10.220.10.0/24. On R2, show ip dhcp binding to see leased addresses.

Task 4: Remove SSH configuration parameters from R2

• Interaction: Access the CLI of Router R2.
• Commands:

  enable
  configure terminal
  no ip ssh version 2
  no crypto key generate rsa
  line vty 0 4
   no transport input ssh
  exit
  end
  copy running-config startup-config
  

• Reasoning:
  • no ip ssh version 2: Specifically disables support for SSH version 2.
  • no crypto key generate rsa: Deletes the RSA key pair, which is fundamental for SSH server operation. This effectively disables the SSH server functionality and removes SSH access.
  • line vty 0 4; no transport input ssh: Removes SSH as an allowed incoming protocol on the Virtual Teletype (VTY) lines, ensuring that SSH connections cannot be established via remote access, even if some SSH components remained.
• Verification (Conceptual): Attempt to SSH to R2 from another device; the connection should fail. On R2, show ip ssh and show crypto key mypubkey rsa should indicate SSH is not enabled and no RSA keys exist.

Common mistakes.

• common_mistake. * Task 1 (PAT): Using a static NAT pool instead of interface ethernet0/0 overload. The question explicitly requires using the interface's IP, which is achieved with the interface keyword in the ip nat inside source command. Failing to properly designate inside/outside interfaces is also a common error.

• Task 2 (NTP): Using ntp broadcast client or ntp broadcast commands, which are explicitly forbidden. Another mistake is configuring an unreachable or incorrect IP address for the NTP server on R3.
• Task 3 (DHCP): On Sw1, failing to configure the ip helper-address on the correct VLAN SVI for VLAN 220, or not creating/configuring the SVI itself. On R2, not defining a DHCP pool for the 10.220.10.0/24 network or providing an incorrect default-router address. On R3, manually configuring an IP address instead of using ip address dhcp.
• Task 4 (SSH): Only using no ip ssh version 2 without removing the RSA crypto keys or restricting SSH access on VTY lines. While no ip ssh version 2 targets a specific version, no crypto key generate rsa is critical for completely disabling the SSH server, and no transport input ssh on VTY lines ensures no remote SSH login is possible. Leaving transport input all or transport input ssh on VTY lines would allow SSH even if ip ssh version 2 is removed (if version 1 is present).

Concept tested. This simulation tests fundamental networking concepts including Network Address Translation (NAT) with Port Address Translation (PAT) and interface overload, Network Time Protocol (NTP) client configuration, Dynamic Host Configuration Protocol (DHCP) server setup, DHCP relay agent (ip helper-address) functionality, DHCP client configuration, and advanced SSH security configuration management (disabling specific SSH versions, removing RSA crypto keys, and controlling Virtual Teletype (VTY) access). It also implicitly verifies understanding of basic routing and Layer 3 switching concepts (SVIs, ip routing).

No community discussion yet for this question.