Legacy mode effects on the system - Grid automation - User Manual - ARM600 M2M Gateway - Arctic series - Relion Protection and Control - 5.0 - IEC - ANSI - 22.06.2023

ARM600 User Manual

To keep backward compatibility with devices configured to use SSHv1, SSH legacy mode was introduced as an option in the ARM600's SSH-VPN settings. When SSH legacy mode is enabled, ARM600 uses the last version of OpenSSH with SSHv1 support included in the CentOS Linux distribution for all SSH-VPN and SSH Patrol connections. This means that if the SSH legacy mode is active, no updates are applied to the OpenSSH server responsible for SSH-VPN and SSH Patrol connections. When the legacy mode is disabled, an up-to-date OpenSSH version is used for all SSH connections. The legacy mode does not affect the SSH console access on port 10022 of ARM600.

Due to the lack of security updates when using this mode, it is highly recommended to avoid using the SSH legacy mode if possible. This is done by:
  1. Updating any SSH-VPN peers using SSH protocol version 1 to use protocol version 2
  2. Disabling the SSH legacy mode in ARM600

In Arctic wireless devices, SSH protocol version 2 is used when the private and public keys used for authentication are set to SSH2 RSA keys.