{
    "mode": "man",
    "parameter": "mii-tool",
    "section": "8",
    "url": "https://www.chedong.com/phpMan.php/man/mii-tool/8/json",
    "generated": "2026-06-15T16:42:56Z",
    "synopsis": "mii-tool  [-v,  --verbose]  [-V,  --version] [-R, --reset] [-r, --restart] [-w, --watch] [-l,\n--log] [-A, --advertise=media,...]  [-F, --force=media] [-p, --phy=addr] interface ...",
    "sections": {
        "NAME": {
            "content": "mii-tool - view, manipulate media-independent interface status\n\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "mii-tool  [-v,  --verbose]  [-V,  --version] [-R, --reset] [-r, --restart] [-w, --watch] [-l,\n--log] [-A, --advertise=media,...]  [-F, --force=media] [-p, --phy=addr] interface ...\n\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "This utility checks or sets the status of a network interface's Media  Independent  Interface\n(MII)  unit.   Most  fast ethernet adapters use an MII to autonegotiate link speed and duplex\nsetting.\n\nMost intelligent network devices use an autonegotiation protocol to  communicate  what  media\ntechnologies  they  support, and then select the fastest mutually supported media technology.\nThe -A or --advertise options can be used to tell the MII to only advertise a subset  of  its\ncapabilities.   Some passive devices, such as single-speed hubs, are unable to autonegotiate.\nTo handle such devices, the MII protocol also allows for establishing a link  by  simply  de‐\ntecting  either  a  10baseT  or 100baseT link beat.  The -F or --force options can be used to\nforce the MII to operate in one mode, instead of autonegotiating.  The -A and -F options  are\nmutually exclusive.\n\nThe  default  short  output reports the negotiated link speed and link status for each inter‐\nface.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "-v --verbose",
                    "content": "Display more detailed MII status information.  If used twice,  also  display  raw  MII\nregister contents.\nAlert:  If used three times, will force reading all MII registers, including non stan‐\ndard ones. It's not guaranteed any valid answer from PHY while PHY  communication  can\neven hang.  With driver e1000e will fail while reading register 0x07.\n",
                    "flag": "-v",
                    "long": "--verbose"
                },
                {
                    "name": "-V --version",
                    "content": "Display program version information.\n",
                    "flag": "-V",
                    "long": "--version"
                },
                {
                    "name": "-R --reset",
                    "content": "Reset the MII to its default configuration.\n",
                    "flag": "-R",
                    "long": "--reset"
                },
                {
                    "name": "-r --restart",
                    "content": "Restart autonegotiation.\n",
                    "flag": "-r",
                    "long": "--restart"
                },
                {
                    "name": "-w --watch",
                    "content": "Watch  interface(s)  and report changes in link status.  The MII interfaces are polled\nat one second intervals.\n",
                    "flag": "-w",
                    "long": "--watch"
                },
                {
                    "name": "-l --log",
                    "content": "Used with -w, records link status changes in the system log  instead  of  printing  on\nstandard output.\n",
                    "flag": "-l",
                    "long": "--log"
                },
                {
                    "name": "-F --force=",
                    "content": "Disable  autonegotiation,  and  force  the  MII  to either 100baseTx-FD, 100baseTx-HD,\n10baseT-FD, or 10baseT-HD operation.\n",
                    "flag": "-F"
                },
                {
                    "name": "-A --advertise=",
                    "content": "Enable and restart autonegotiation, and advertise only the specified  media  technolo‐\ngies.   Multiple  technologies  should  be  separated  by  commas.   Valid  media  are\n100baseT4, 100baseTx-FD, 100baseTx-HD, 10baseT-FD, and 10baseT-HD.\n",
                    "flag": "-A"
                },
                {
                    "name": "-p --phy=",
                    "content": "Override the MII address provided by kernel with value addr.\n\n",
                    "flag": "-p"
                }
            ]
        },
        "DIAGNOSTICS": {
            "content": "SIOCGMIIPHY on 'eth?' failed: Invalid argument\nIf the interface is not running (up), kernel will refuse to report its link state.\n\nSIOCGMIIPHY on 'eth?' failed: Operation not permitted\nMost kernels restrict access to root.\n\nSIOCGMIIPHY on 'eth?' failed: No such device\nThis error is shown, if the kernel does not know about the named device.\n\nSIOCGMIIPHY on 'eth?' failed: Operation not supported\nThe interface in question does not support MII queries. Most likely, it does not  have\nMII transceivers, at all.\n\n",
            "subsections": []
        },
        "AUTHORS": {
            "content": "David Hinds - dhinds@pcmcia.sourceforge.org\nDonald Becker - becker@scyld.com\nBernd Eckenfels - net-tools@lina.inka.de\n\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "http://net-tools.sourceforge.net - Homepage of the net-tools project\n\n\n\nnet-tools                                    2013-02-15                                  MII-TOOL(8)",
            "subsections": []
        }
    },
    "summary": "mii-tool - view, manipulate media-independent interface status",
    "flags": [
        {
            "flag": "-v",
            "long": "--verbose",
            "arg": null,
            "description": "Display more detailed MII status information. If used twice, also display raw MII register contents. Alert: If used three times, will force reading all MII registers, including non stan‐ dard ones. It's not guaranteed any valid answer from PHY while PHY communication can even hang. With driver e1000e will fail while reading register 0x07."
        },
        {
            "flag": "-V",
            "long": "--version",
            "arg": null,
            "description": "Display program version information."
        },
        {
            "flag": "-R",
            "long": "--reset",
            "arg": null,
            "description": "Reset the MII to its default configuration."
        },
        {
            "flag": "-r",
            "long": "--restart",
            "arg": null,
            "description": "Restart autonegotiation."
        },
        {
            "flag": "-w",
            "long": "--watch",
            "arg": null,
            "description": "Watch interface(s) and report changes in link status. The MII interfaces are polled at one second intervals."
        },
        {
            "flag": "-l",
            "long": "--log",
            "arg": null,
            "description": "Used with -w, records link status changes in the system log instead of printing on standard output."
        },
        {
            "flag": "-F",
            "long": null,
            "arg": null,
            "description": "Disable autonegotiation, and force the MII to either 100baseTx-FD, 100baseTx-HD, 10baseT-FD, or 10baseT-HD operation."
        },
        {
            "flag": "-A",
            "long": null,
            "arg": null,
            "description": "Enable and restart autonegotiation, and advertise only the specified media technolo‐ gies. Multiple technologies should be separated by commas. Valid media are 100baseT4, 100baseTx-FD, 100baseTx-HD, 10baseT-FD, and 10baseT-HD."
        },
        {
            "flag": "-p",
            "long": null,
            "arg": null,
            "description": "Override the MII address provided by kernel with value addr."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "MII-TOOL",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/MII-TOOL/8/json"
        }
    ]
}