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Cisco ASA lab 13 of 15

Troubleshooting with packet-tracer, captures and ASP drops

A weekend change broke both the office's internet access and the public web site. Use packet-tracer, packet captures, ASP drop captures, ARP, NAT and connection tables to find four separate faults (three on the firewall, one on the server) and prove each fix.

Run this lab

It needs Lite: its 4 nodes are set to 4 vCPU and 3,584 MB in total. That fits the free demo too.

In your workspace: Shared, then Cisco ASA Firewall SCOR 350-701 guided labs, then 13 - Troubleshooting with packet-tracer captures and ASP drops

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Level
Advanced
Time
About 75 minutes
Nodes need
4 vCPU, 3,584 MB
Smallest plan
Lite

The scenario

A contractor "tidied up" HQ-FW and the web server over the weekend. On Monday two tickets arrive:

  • Ticket 1: "Nobody in the office can reach the internet." (Test from PC1: ping 198.51.100.10, telnet 198.51.100.10 80.)
  • Ticket 2: "The public web site is down." (Test from ISP: telnet 203.0.113.10 80.)

The intended design has not changed: office PAT to the outside address, the web server published at 203.0.113.10 port 80, the ISP's gateway at 203.0.113.1. There are four faults in total, and not all of them are on the firewall. Find each one with evidence before you change anything, then fix it and prove the fix.

What you’ll practise

  • Run packet-tracer for a simulated flow and read every phase
  • Capture traffic on ASA interfaces with filters, and capture ASP drops
  • Use show arp, show route, show nat detail, show xlate, show conn and syslog together
  • Prove whether a fault is on the firewall or beyond it
  • Fix routing, NAT, ACL and server faults and verify end to end

The tasks

  1. Reproduce both tickets
  2. Ticket 1, the office's internet access
  3. Ticket 2, the web site
  4. Clean up

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Troubleshooting with packet-tracer captures and ASP drops4 nodes, 3 links. Every link is listed as text below the diagram.HQ-FWPC1WEBISPGi0/1Gi0/0Gi0/0Gi0/0Gi0/2Gi0/0
4 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • HQ-FW Gi0/0 to PC1 Gi0/0
  • HQ-FW Gi0/1 to ISP Gi0/0
  • HQ-FW Gi0/2 to WEB Gi0/0
Nodes in Troubleshooting with packet-tracer, captures and ASP drops, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
HQ-FWCisco ASAvasav-9.22.1.1-PLR-Licensed1 vCPU, 2,048 MB
PC1Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
WEBCisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
ISPCisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder Cisco ASA Firewall SCOR 350-701 guided labs.

  3. Open 13 - Troubleshooting with packet-tracer captures and ASP drops and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.