Inspect and set NIC hardware parameters quickly from the shell to improve reliability and performance. 27.12.2025 | reading time: 2 min When a link drops or throughput is lower than expected, `ethtool` is the low-level key to diagnose and fix NIC problems; it talks directly to the driver and hardware and lets the administrator read stats, change speed and duplex, toggle Wake on LAN and tune ring buffers. Inspecting a NIC Run `ethtool enp3s0` to see current settings and supported modes; for example running `ethtool enp3s0` might show `Settings for enp3s0: Supported ports: [ TP ] Supported link modes: 1000baseT/Full ... Speed: 1000Mb/s Duplex: Full Port: Twisted Pair` which confirms negotiated speed and duplex. Forcing speed and duplex If autonegotiation fails on a switch, execute `ethtool -s enp3s0 speed 1000 duplex full autoneg off` to force 1Gbps full duplex; verify with `ethtool enp3s0` which should report `Speed: 1000Mb/s Duplex: Full Autoneg: off`; note that forcing settings can break connectivity if the peer is set differently, so always check the switch side first. Tuning rings, WOL and diagnostics Adjust receive and transmit ring sizes with `ethtool -G enp3s0 rx 512 tx 512` to reduce dropped packets under load; enable Wake on LAN with `ethtool -s enp3s0 wol g`; gather stats with `ethtool -S enp3s0` and driver info with `ethtool -i enp3s0`; use `ethtool -p enp3s0` to blink LEDs when identifying a server in a rack. When ethtool is not enough Some virtual NICs or advanced features such as SR-IOV and offloads require vendor tools or driver-specific interfaces; combine `ethtool` with `ip link` and the driver log to correlate configuration and kernel messages when troubleshooting complex issues. Wrap up and next steps ethtool is a short, powerful tool that gives direct control over NIC behavior; practice on a test interface, record changes, and add safe checks to scripts before applying to production; deepen skills with structured learning and consider certification paths like CompTIA Linux+ or LPIC-1 and intensive exam prep at bitsandbytes.academy to turn hands-on knowhow into credentials. Join Bits & Bytes Academy First class LINUX exam preparation. network utilities troubleshooting infrastructure
