netdev - Re: wake-on-lan

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Date:   Wed, 15 Jul 2020 17:10:18 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Michal Kubecek <mkubecek@...e.cz>,
        "Michael J. Baars" <mjbaars1977.netdev@...erfiber.eu>
Cc:     netdev@...r.kernel.org
Subject: Re: wake-on-lan

On 15.07.2020 15:39, Michal Kubecek wrote:
> On Wed, Jul 15, 2020 at 11:27:20AM +0200, Michael J. Baars wrote:
>> Hi Michal,
>>
>> This is my network card:
>>
>> 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 0c)
>> 	Subsystem: Realtek Semiconductor Co., Ltd. Device 0123
>> 	Kernel driver in use: r8169
>>
>> On the Realtek website
>> (https://www.realtek.com/en/products/communications-network-ics/item/rtl8168e)
>> it says that both wake-on-lan and remote wake-on-lan are supported. I
>> got the wake-on-lan from my local network working, but I have problems
>> getting the remote wake-on-lan to work.
>>
>> When I set 'Wake-on' to 'g' and suspend my system, everything works
>> fine (the router does lose the ip address assigned to the mac address
>> of the system). I figured the SecureOn password is meant to forward
>> magic packets to the correct machine when the router does not have an
>> ip address assigned to a mac address, i.e. port-forwarding does not
>> work.
>>
>> Ethtool 'Supports Wake-on' gives 'pumbg', and when I try to set 'Wake-on' to 's' I get:
>>
>> netlink error: cannot enable unsupported WoL mode (offset 36)
>> netlink error: Invalid argument
>>
>> Does this mean that remote wake-on-lan is not supported (according to
>> ethtool)?
> 
> "MagicPacket" ('g') means that the NIC would wake on reception of packet
> containing specific pattern described e.g. here:
> 
>   https://en.wikipedia.org/wiki/Wake-on-LAN#Magic_packet
> 
> This is the most frequently used wake on LAN mode and, in my experience,
> what most people mean when they say "enable wake on LAN".
> 
> The "SecureOn(tm) mode" ('s') is an extension of this which seems to be
> supported only by a handful of drivers; it involves a "password" (48-bit
> value set by sopass parameter of ethtool) which is appended to the
> MagicPacket.
> 
> I'm not sure how is the remote wake-on-lan supposed to work but
> technically you need to get _any_ packet with the "magic" pattern to the
> NIC.
> 
WoL is MAC-based and works on layer 2 only. WoW (Wake-on-WAN) requires
routing and therefore a running IP stack. In sleep mode the BIOS has
to provide this. One approach was DASH: https://www.dmtf.org/standards/dash

Realtek provides a DASH Windows client, however it's limited to specific
network chip set versions and systems (as it requires BIOS support).

>> I also tried to set 'Wake-on' to 'b' and 'bg' but then the systems
>> turns back on almost immediately for both settings.
> 
> This is not surprising as enabling "b" should wake the system upon
> reception of any broadcast which means e.g. any ARP request. Enabling
> multiple modes wakes the system on a packet matching any of them.
> 
> Michal
>