🌐 Networking March 10, 2026 5

Linux Command: ethtool

Display or change ethernet device settings

Terminal — Networking

Command

$ ethtool eth0

Output

Shows link speed, duplex, auto-negotiation, and link status.

ethtool displays and modifies Ethernet device settings. It shows link speed, duplex mode, auto-negotiation status, driver information, and hardware features for network interfaces. ethtool is essential for diagnosing network performance issues, verifying link speed, checking cable connectivity (link detection), and tuning network interface parameters. ethtool works with physical and virtual Ethernet interfaces. It requires root for modifying settings but can display information without root on most systems.

Syntax

ethtool [OPTION]... DEVNAME

Common Examples

ethtool eth0 — Shows link speed, duplex, auto-negotiation, and link status.
ethtool -i eth0 — Shows the kernel driver, version, and firmware for the NIC.
ethtool -S eth0 | head -20 — Shows detailed NIC statistics including errors and drops.
sudo ethtool -p eth0 10 — Blinks the port LED for 10 seconds to identify the physical NIC.