🛠 Ethernet Gigabit et accès SSH

Objectives

Install the ODROID-C2 without a screen (headless), verify that the Gigabit Ethernet link — the board's true asset: Realtek RTL8211F PHY over RGMII, no USB bridge — negotiates correctly at 1000 Mbit/s, and control the board via SSH from a machine on the local network.

Hardware

• ODROID-C2 with an Armbian or DietPi image written to a microSD card or eMMC module
• RJ45 cable to a Gigabit box/router (the C2 has no built-in Wi-Fi or Bluetooth)
• Original 5 V / 2 A power supply (2.5x0.8 mm jack)
• A machine with ssh and iperf3 for bandwidth testing

Complete code

# --- Sur la carte (apres premiere connexion, console serie ou ecran) ---
sudo nmtui                                   # ou : sudo armbian-config > Network
ip -br addr                                  # noter l'IP (ex. 192.168.1.42)

# --- Depuis le poste ---
ssh root@192.168.1.42                        # changer le mot de passe immediatement !

# --- Verifier le lien Gigabit (PHY RTL8211F) ---
sudo ethtool eth0 | grep -E 'Speed|Duplex'   # attendu: 1000Mb/s Full

# --- Debit reel vers une machine du LAN (attendu ~600+ Mbit/s) ---
# cote serveur : iperf3 -s
iperf3 -c 192.168.1.10

# --- Durcir : creer un utilisateur, couper le root SSH ---
sudo adduser admin
sudo sed -i 's/^PermitRootLogin.*/PermitRootLogin no/' /etc/ssh/sshd_config
sudo systemctl restart ssh

Expected verification

ethtool shows Speed: 1000Mb/s and Duplex: Full; iperf3 reports a throughput of around 600 Mbit/s or more, which a Raspberry Pi 3 (100 Mbit over USB) cannot achieve. SSH reconnection with the created user works, while root is refused.

Common errors

• Cable or port limited to 100 Mbit: ethtool shows 100Mb/s — check the router AND the cable before blaming the board.
• Looking for the "wlan0" interface: there is no radio on the C2, only eth0 (unless using a USB dongle).
• Leaving root with the default password exposed: the board must be hardened before any network exposure.
• Powering via micro-USB OTG with a weak charger: reboots under network load (brown-out).
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