Bastion via SHH with a key works post VM restore then fails next day onward

Question

Bastion via SHH with a key works post VM restore then fails next day onward

Rick Regello 0

Simple Ubuntu VM. Bastion works one day but not the next. If I restore the server to the first backup, bastion works for a day only. Any guidance would be great.

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Answer 1

Hi @ Rick Regello,

Welcome to Microsoft Q&A Platform.

Since Bastion works immediately after restoring the VM and then stops again later, this may indicate the issue is occurring inside the VM or due to a configuration change over time rather than the Bastion resource itself.

Please check the below settings

Verify SSH service status on the VM after the issue occurs:

sudo systemctl status ssh
sudo journalctl -u ssh

Review recent changes:

OS updates
startup scripts / cloud-init
cron jobs
firewall rules (ufw, iptables)
SSH configuration changes

Verify networking:

NSG allows inbound TCP/22 from Azure Bastion

No UDR or firewall changes affecting connectivity
Review Bastion diagnostics: Azure Portal → Bastion → Diagnose and solve problems

Compare VM state before/after the failure window to identify what changes between the working and non-working state.

References:

Troubleshoot Azure Bastion connections

Connect to Linux VM using Azure Bastion SSH

Network security groups for Azure Bastion

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