{{Short description|Linux network configuration tool}} {{Multiple issues| {{More citations needed|date=November 2020}} {{One source|date=November 2020}} }} {{Lowercase title}} {{Infobox software | name = | title = ethtool | logo = | screenshot = | caption = | author = David S. Miller | developer = Michal Kubecek | released = {{start date and age|1998}} | latest release version = 6.15 | latest release date = {{Start date and age|2025|6|23|df=yes}} | programming language = C | operating system = Linux | genre = Networking | license = GPLv2 | website = {{URL|https://www.kernel.org/pub/software/network/ethtool/}} }}
'''ethtool''' is the primary means in Linux kernel-based operating systems (primarily Linux and Android) for displaying and modifying the parameters of network interface controllers (NICs) and their associated device driver software from application programs running in userspace.
ethtool consists of two components, an API within the Linux kernel through which NICs can send and receive parameters through their device driver software, and a userspace API based on the Linux SIOCETHTOOL ioctl mechanism through which application programs can communicate with the kernel to send and receive NIC and NIC driver parameters.
Most Linux distributions provide a standard utility program called [https://man7.org/linux/man-pages/man8/ethtool.8.html ethtool] that can be used from a shell to control, or gather information from NICs using the ethtool userspace API. In the Information technology community, the term ''ethtool'' is usually used to refer to this utility program.
The ethtool userspace API can be accessed from programs written in the C and C++ programming languages through the C standard library or C++ standard library respectively.
Several scripting languages such as Perl and Python provide ethtool API bindings that allow programmers using these languages to write scripts that can control NIC's.
The macOS and FreeBSD operating systems provide utility programs that have a user interface similar to the Linux ethtool utility, but that use fundamentally different APIs to communicate with their operating system kernels and NIC's.
==Usage== The command is useful for: * Identification and diagnosis of Ethernet devices * Extended Ethernet devices statistics * Control speed, duplex, autonegotiation and flow control for Ethernet devices * Control checksum offload and other hardware offload features, such as large receive offload and large send offload * Control DMA ring sizes and interrupt moderation * Control receive queue selection for multiqueue devices * Upgrade firmware in flash memory
== Examples == To display the current parameters of the first network port ({{Mono|eth0}}): <syntaxhighlight lang="console"> $ ethtool eth0 Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised auto-negotiation: No Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 1 Transceiver: internal Auto-negotiation: off Supports Wake-on: g Wake-on: g Current message level: 0x00000007 (7) Link detected: yes </syntaxhighlight><ref>{{Cite web |date=2010-10-28 |title=9 Linux ethtool Examples to Manipulate Ethernet Card (NIC Card) |url=https://www.thegeekstuff.com/2010/10/ethtool-command/ |access-date=2020-11-14 |website=www.thegeekstuff.com}}</ref>
To configure it with the 1000 Mb/s speed and duplex, in 1000BASE-T: <syntaxhighlight lang="console"> $ ethtool -s eth0 speed 1000 duplex full autoneg off </syntaxhighlight>
To let the link light of the device eth0 flash for two minutes: <syntaxhighlight lang="console"> $ ethtool -p eth0 120 </syntaxhighlight>To print the driver info of the interface eth0:<syntaxhighlight lang="console"> $ ethtool -i eth0 driver: mlx5_core version: 4.9-2.2.4 firmware-version: 14.28.2006 (MT_2420110034) expansion-rom-version: bus-info: 0000:65:00.1 supports-statistics: yes supports-test: yes supports-eeprom-access: no supports-register-dump: no supports-priv-flags: yes </syntaxhighlight>
==mii-tool== '''mii-tool''' is an older program performing a similar function to ethtool. Since 2003,<ref>{{cite web|url=http://lists.olug.org/pipermail/olug/2003-September/010415.html|title=Ethernet Auto-negotiation and Duplexing on Linux|website=lists.olug.org|date=September 2003}}</ref> it's considered obsolete and replaced by ethtool.
===Example=== To display the current parameters: <syntaxhighlight lang="console"> $ mii-tool eth0: no autonegotiation, 100baseTx-HD, link ok </syntaxhighlight> To force the network speed to 1 Gbit/s, and the ''duplex'' in ''full'' on the port 1 (eth0): <syntaxhighlight lang="console"> $ mii-tool -F 1000baseTx-FD eth0 $ mii-tool eth0: 1 000 Mbit, full duplex, link ok </syntaxhighlight>
==See also== {{Portal|Free and open-source software}} * iproute2
==References== {{Reflist}}
==External links== * {{Official website|https://www.kernel.org/pub/software/network/ethtool/}} * [http://www.thegeekstuff.com/2010/10/ethtool-command/ Ethtool examples] * [https://sourceforge.net/projects/net-tools/ Net Tools on sourceforge.net]
{{Unix commands}}
Category:Linux network-related software Category:Linux configuration utilities Category:Linux-only free software Category:Free network-related software