Wake-on-lan packages don't get through

[Paul Schenkeveld]

Hi,

On Tue, Dec 16, 2008 at 07:22:39PM +0100, Markus Hitter wrote:
> 
> Hello all,
> 
> glad to have found a binary[1] wake-on-lan program, I obvserve different 
> behaviour of /usr/bin/wol on my full-size FreeBSD and my TinyBSD. From the 
> full-size BSD (VirtualBox on Linux), i could capture this package after 
> issueing wol:
> 
> 18:50:30.019039 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP 
> (17), length 130) piccard.jump-ing.de.37597 > 255.255.255.255.40000: [bad 
> udp cksum b716!] UDP, length 102
> 
> This package woke the targeted Macintosh. Doing the same on the embedded 
> Flepo, I get:
> 
> 01:38:35.500497 IP (tos 0x0, ttl 64, id 40022, offset 0, flags [none], 
> proto UDP (17), length 130, bad cksum 0 (->d401)!) git.jump-ing.de.50582 > 
> 255.255.255.255.40000: [bad udp cksum a1e4!] UDP, length 102
> 
> The later doesn't get through the switch, I can capture it on the sending 
> host only. Accordingly, the Mac keeps sleeping.

Please show a tcpdump -e output here.  The wake-on-lan packet should
be sent to the ethernet broadcast address (ff:ff:ff:ff:ff:ff) for the
switch to send it to all ports (which is needed since it can't learn mac
address from switched off nodes).

On some of my machines I need to explicitely send the packet to the
IP LAN broadcast address, e.g. 192.168.1.255 (assuming /24 netmask).

> As both "wol" binaries are the very same (copied), I can rule out 
> compilation errors. To be more funny, the Flepo serves web pages just fine. 
> What does go wrong here?

What about the kernels, are they the same version?  and does your
embedded system have more than one ethernet interface?

> Thanks for any enlightenment,
> Markus

HTH

> [1] Using wakeonlan requires Perl, which in turn would more than double the 
> size of the installation on the embedded box.
> 
> - - - - - - - - - - - - - - - - - - -
> Dipl. Ing. Markus Hitter
> http://www.jump-ing.de/

Paul Schenkeveld