Unable SSH/SFTP from Azure VM to On-Prem Linux Server with error “Key_exchange_identification : read connection time out, Banner exchange time out"

Question

I'm currently facing an issue connecting via SSH and SFTP from an Azure VM (Windows Server 2022) to an on-premises Linux server (RedHat 8.9).

error_details_image

Here are the details:

1. Environment

   • Azure Firewall deployed between the Azure VM and the on-premises server
   • Site-to-Site VPN established for connectivity
   • SSH version for AzureVM : "OpenSSH_for_Windows_9.5p1, LibreSSL 3.8.2"
   • SSH version LinuxServer : "OpenSSH_8.0p1, OpenSSL 1.1.1k FIPS 25 Mar 2021"

2. Connectivity Status

   • Networking is working fine between them validated by Test-NetConnection and Azure Connection troubleshooter
   • Able to connect to the on-premises Linux server using WinSCP from the Azure VM.
   • Laptop, devices, Cloudera containers, another on-prem Linux machine, WinSCP and Putty all can ssh/sftp to the VM except built-in openssh in Windows.

3. Troubleshooting Steps and Findings:

   • ssh -vvv user@xxxxx: Fails with authentication error

   ssh_error_details_image

Given that I can connect using WinSCP, and network diagnostics confirm no connectivity issues between the Azure VM and the on-premises Linux server.

Is there something specific I should check in the SSH configuration or authentication setup on the on-premises Linux server and Azure VM?

Any help or guidance would be greatly appreciated! Thanks in advance!