Date:   Thu, 16 Jul 2020 09:28:23 +0200
From:   "Michael J. Baars" <mjbaars1977.netdev@...erfiber.eu>
To:     Michal Kubecek <mkubecek@...e.cz>
Cc:     netdev@...r.kernel.org
Subject: Re: wake-on-lan

On Wed, 2020-07-15 at 15:39 +0200, 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".
> 

Yes, about that. I've tried the 'system suspend' with 'ethtool -s 
enp1s0' wol g' several times this morning. It isn't working as fine as
I thought it was. The results are in the attachment, five columns for
five reboots, ten rows for ten trials. As you can see, the wake-on-lan
isn't working the first time after reboot. You can try for yourself, I
run kernel 5.7.8.

> 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.
> 

Funny, it looks more like a mac address to me than like a password :) 

> 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.

> > 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.

Like this? We put it on the broadcast address?

> 
> > 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.
> 

I think the "bg" was supposed to wake the system on a packet matching
both of them. We want to wake up on a packet with the magic packet
signature on the broadcast address,

> _any_ packet with the "magic" pattern

> Michal



Download attachment "wake-on-lan.ods" of type "application/vnd.oasis.opendocument.spreadsheet" (8691 bytes)

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