Expert · Incident · 16 of 180:00 / 20:00

The API stopped answering Spoke 1

Problem

Spoke 1 can't call the API in Spoke 2.

Your job
  • Get vm-spoke1 reaching the API on vm-api (443) through azfw-hub
Without breaking
  • Keep SSH from Spoke 1 to vm-api blockedbroken
  • Keep UFW running on vm-apibroken
  • Don't peer the spokes to each otherbroken
Background

"Since azfw-hub went in, Spoke 1 can't call the API in Spoke 2." The API runs on vm-api on 443, and vm-spoke1 calls it. The design: spoke-to-spoke traffic goes through azfw-hub, an Azure Firewall at 10.0.1.4, with HTTPS allowed from Spoke 1 to Spoke 2. SSH from Spoke 1 stays blocked, the spokes are never peered, and UFW on vm-api stays on.

How to work it
  1. 1See it fail

    Prove the problem yourself before you change anything. Reports are often wrong.

    VM commands forVMs: Linux
    1. ssh vm-spoke1
      What's this?

      Opens a shell on vm-spoke1, so the next commands run on that VM. In this lab it's a shortcut. In real Azure you'd connect through something like Azure Bastion, or SSH to an address you can reach.

    2. nc -zv 10.2.1.4 443
      What's this?

      netcat, a standard Linux tool. Tries to open a TCP connection and reports whether it worked.

      • -z only check whether the port answers. Send no data
      • -v print the result in words
      • 10.2.1.4 where to connect
      • 443 the port to try

    Ticks off when the test runs on vm-spoke1.

  2. 2Find where it stops
  3. 3Name the cause
  4. 4Fix it and test again
Sources on Microsoft Learn (4)
0/2 changes
Network map
?
  • Resource group, the outer dashed frame
  • Virtual network, with its address space top right
  • Subnet, with range and usable IPs (5 reserved)
  • Network security group. A small shield on a VM's NIC means the NIC has one too
  • Route table on the subnet
  • NICVM Appliance Private endpoint
  • Peering Connected Initiated or access off
  • Goal working Goal broken, X marks where it stops
  • Private DNS zone, dotted lines go to linked VNets
  • Orange pulse: what your last command changed. Drag to pan, Ctrl and scroll to zoom.
Resource grouprg-labvnet-spoke1: tap to inspectVirtual networkvnet-spoke110.1.0.0/16subnet-app: tap to inspectsubnet-app10.1.1.0/24 · 251 usablert-spoke1vm-spoke1 10.1.1.4: tap to inspectNICvm-spoke110.1.1.4vnet-hub: tap to inspectVirtual networkvnet-hub10.0.0.0/16AzureFirewallSubnet: tap to inspectAzureFirewallSubnet10.0.1.0/26 · 59 usableazfw-hub 10.0.1.4: tap to inspectFWazfw-hub10.0.1.4vnet-spoke2: tap to inspectVirtual networkvnet-spoke210.2.0.0/16subnet-api: tap to inspectsubnet-api10.2.1.0/24 · 251 usablert-spoke2vm-api 10.2.1.4: tap to inspectNICvm-api10.2.1.4Connected: tap to inspectpeeredConnected: tap to inspectpeered
  • vm-spoke1 → vm-api:443should work: not working
  • vm-spoke1 → vm-api:22should stay blocked: blocked
Goals 0/4
Cloud Shell · bashVMs: Linuxrg-lab · eastus2
cloudshell:~$