Intermediate · Traffic filtering · 4 of 15

Peered partner can't reach the web app

Problem

vm-partner can't load the HTTPS site on vm-web.

Your job
  • Get vm-partner reaching vm-web on 443
Without breaking
  • Keep SSH (22) from vm-partner to vm-web blockedbroken
Background

vm-web (10.1.1.4) in vnet-app hosts an HTTPS site for a partner team. Their vm-partner (10.5.1.4) sits in vnet-partner, which is peered with vnet-app. They still can't load the site. There's an allow rule for them in nsg-web, so it should work. Working means vm-partner gets in on 443 while SSH (22) stays closed.

How to work it
  1. 1See it fail

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

    VM commands forVMs
    1. ssh vm-partner
      What's this?

      Opens a shell on vm-partner, 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 10.1.1.4 443
      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
      • 10.1.1.4 where to connect
      • 443 the port to try

    Ticks off when the test runs on vm-partner.

  2. 2Find where it stops
  3. 3Name the cause
  4. 4Fix it and test again
  5. 5Explain it
Sources on Microsoft Learn (2)
0/1 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-app: tap to inspectVirtual networkvnet-app10.1.0.0/16subnet-web: tap to inspectsubnet-web10.1.1.0/24 · 251 usablensg-webvm-web 10.1.1.4: tap to inspectNICvm-web10.1.1.4vnet-partner: tap to inspectVirtual networkvnet-partner10.5.0.0/16subnet-app: tap to inspectsubnet-app10.5.1.0/24 · 251 usablevm-partner 10.5.1.4: tap to inspectNICvm-partner10.5.1.4Connected: tap to inspectpeered:443 ✗
  • vm-partner → vm-web:443should work: not working
  • vm-partner → vm-web:22should stay blocked: blocked
Goals 0/3
Cloud Shell · bashVMsrg-lab · eastus2
cloudshell:~$