Check Ethernet Link Speed in Ubuntu

Check Ethernet Link Speed in Ubuntu | Generated by AI

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In Ubuntu, you can check the Ethernet link speed using several command-line tools. Here are the most common methods:

1. Using `ethtool` (Recommended)

ethtool is the most reliable way to check the current link speed of your Ethernet interface.

Install `ethtool` (if not already installed):

sudo apt install ethtool

Check the link speed:

sudo ethtool <interface_name>

Replace <interface_name> with your Ethernet interface (e.g., eth0, enp3s0, ens33).

Example:

sudo ethtool enp3s0

Look for the Speed and Duplex fields in the output:

Settings for enp3s0:
    Supported ports: [ TP ]
    Supported link modes:   10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Full 
    Supported pause frame use: No
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Full 
    Advertised pause frame use: No
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Speed: 1000Mb/s   # <--- This is your current link speed
    Duplex: Full      # <--- Full or Half duplex
    Port: Twisted Pair
    PHYAD: 1
    Transceiver: internal
    Auto-negotiation: on
    MDI-X: on (auto)
    Supports Wake-on: pumbg
    Wake-on: d
    Current message level: 0x00000007 (7)
                           drv probe link
    Link detected: yes      # <--- Indicates if the cable is connected

2. Using `ip` or `ifconfig` (Basic Info)

These commands show whether the interface is up but do not directly display link speed.

Using `ip`:

ip link show <interface_name>

Example:

ip link show enp3s0

(Does not show speed, just link status.)

Using `ifconfig` (deprecated but still used):

ifconfig <interface_name>

Example:

ifconfig enp3s0

(Shows if the interface is up but not speed.)

3. Using `dmesg` (Check Driver Logs)

Sometimes, the Ethernet driver logs the negotiated speed during initialization.

dmesg | grep <interface_name>

Example:

dmesg | grep enp3s0

Look for lines like:

[    5.123456] e1000e: enp3s0 NIC Link is Up 1000 Mbps Full Duplex

4. Using `mii-tool` (Older Systems)

For very old systems, mii-tool might work:

sudo apt install net-tools
sudo mii-tool -v <interface_name>

Example:

sudo mii-tool -v eth0

(Not recommended for modern Gigabit Ethernet.)

Summary

Best method: sudo ethtool <interface> (shows speed, duplex, auto-negotiation).
Alternative: Check dmesg logs if ethtool is unavailable.
Basic status: ip link show or ifconfig (does not show speed).

Let me know if you need further clarification! 🚀

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