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JNCIA-SEC and JNCIS-SEC lab 8 of 16

VPN troubleshooting with traceoptions

A VPN that has never worked has five faults, one behind another. Use IKE traceoptions and SA output on both ends to find each one, fix it, and leave the firewalls clean.

Run this lab

It needs Standard: its 5 nodes are set to 7 vCPU and 10,752 MB in total.

In your workspace: Shared, then JNCIA-SEC and JNCIS-SEC SRX security guided labs, then 08 - VPN troubleshooting with traceoptions

Run it on Standard from £5 a day

The free demo can’t run it: it has 6 vCPU and 8 GB, and this lab’s nodes need 7 vCPU and 10,752 MB together. Every lab plan includes every guided lab.

Level
Advanced
Time
About 80 minutes
Nodes need
7 vCPU, 10,752 MB
Smallest plan
Standard

The scenario

A contractor built the Poole to Falmouth VPN from the design sheet in lab 6 and left. It has never come up. There are five faults between the two firewalls, one behind another: fixing one uncovers the next. Find them from the evidence, comparing both ends with the sheet. Don't retype the configuration.

DeviceInterfaceAddressNotes
ISPGi0/0 / Gi0/1198.51.100.1/30 / 203.0.113.1/30The internet between the sites
SRX-HQge-0/0/0198.51.100.2/30Zone untrust, default route to the ISP
SRX-HQge-0/0/110.10.10.1/24Zone trust, Poole LAN
HQ-PCeth010.10.10.10/24Gateway 10.10.10.1
SRX-BRge-0/0/0203.0.113.2/30Zone untrust, default route to the ISP
SRX-BRge-0/0/110.20.10.1/24Zone trust, Falmouth LAN
BR-PCeth010.20.10.10/24Gateway 10.20.10.1
Design sheetValue
IKE proposalPre-shared keys, DH group 20, SHA-256, AES-256-CBC, 28,800 s
Pre-shared keyHartwell-VPN-2027
IPsec proposalESP, HMAC-SHA-256-128, AES-256-CBC, 3,600 s, PFS group 20
Tunnelst0.0, 172.16.12.1/30 and .2/30, zone vpn on both ends

What you’ll practise

  • Enable and read IKE traceoptions
  • Tell a path or host-inbound problem from a proposal, authentication or phase 2 problem
  • Work through a VPN in order: path, phase 1, phase 2, traffic
  • Remove debugging when finished

The tasks

  1. Turn on the evidence
  2. Work through the faults
  3. Traffic
  4. Tidy 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 VPN troubleshooting with traceoptions5 nodes, 4 links. Every link is listed as text below the diagram.ISPSRX-HQSRX-BRHQ-PCBR-PCge-0/0/1eth0ge-0/0/1eth0ge-0/0/0Gi0/0ge-0/0/0Gi0/1
5 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • SRX-HQ ge-0/0/0 to ISP Gi0/0
  • SRX-BR ge-0/0/0 to ISP Gi0/1
  • SRX-HQ ge-0/0/1 to HQ-PC eth0
  • SRX-BR ge-0/0/1 to BR-PC eth0
Nodes in VPN troubleshooting with traceoptions, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
ISPCisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
SRX-HQJuniper vSRX NextGen templatevsrxng-24.4R1.92 vCPU, 4,096 MB
SRX-BRJuniper vSRX NextGen templatevsrxng-24.4R1.92 vCPU, 4,096 MB
HQ-PCEVE-NG GUI server (Docker)eve-gui-server:latest1 vCPU, 1,024 MB
BR-PCEVE-NG GUI server (Docker)eve-gui-server:latest1 vCPU, 1,024 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 JNCIA-SEC and JNCIS-SEC SRX security guided labs.

  3. Open 08 - VPN troubleshooting with traceoptions 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 and Juniper Networks. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.