5.4Accessing devices and collecting data

Diagnosis presupposes being able to access the target device and pull information. Do you operate it remotely from your PC, attach a cable right in front of it, or enter the office network safely from outside?—the right means changes with the situation. This section covers the representative access and data-collection means, from the viewpoint of when to use each: remote operation with RDP/SSH/Telnet (mind encryption), VPN for outside connection, direct console connection with a terminal emulator, NMS and cloud management (Meraki) that bundle many devices, and scripts for automation.

5.4.1Remote access, VPN, and console

• RDP remotely operates mainly a Windows desktop screen (the whole GUI). SSH is the standard way to connect to servers and network devices over an encrypted, secure CLI. Telnet is also a CLI connection but is unencrypted, sending even passwords in clear text, so it is discouraged—use SSH today.
• VPN builds an encrypted tunnel across the internet from an outside device to connect safely into the office network. It is often the prerequisite for diagnosing internal devices from home or while traveling.
• A console connection attaches a cable directly to the device's console port and operates it with a terminal emulator (PuTTY, Tera Term, etc.) on the PC. It is the last resort for reaching a device you cannot enter over the network or one in an initial state with no IP set.