Some users get errors, others are fine
The sales team gets timeouts on the portal, and one server dropped out of rotation.
- Get vm-acct and vm-sales both reaching lb-portal on 443
- Get vm-web1 and vm-web2 both passing the health probe
- Keep SSH from users to the servers blockedbroken
- Keep UFW running on both serversbroken
Background
"Accounting can use the portal, but the sales team, new since Monday, gets timeouts. And ops says one server dropped out of rotation." The portal runs on vm-web1 and vm-web2 behind lb-portal, an internal load balancer at 10.1.1.10. Accounting is subnet-acct, sales is the new subnet-sales. Users never get SSH to the servers, and UFW stays on on both.
- 1See it fail
Prove the problem yourself before you change anything. Reports are often wrong.
VM commands forVMs: Linuxssh vm-salesWhat's this?
Opens a shell on vm-sales, 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.
nc -zv 10.1.1.10 443What's this?
netcat, a standard Linux tool. Tries to open a TCP connection and reports whether it worked.
-zonly check whether the port answers. Send no data-vprint the result in words10.1.1.10where to connect443the port to try
Ticks off when the test runs on vm-sales.
- 2Find where it stops
- 3Name the cause
- 4Fix it and test again
?
- 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
- VM 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.
vm-sales → lb-portal-fe:443should work: not workingvm-acct → lb-portal-fe:443should work: working