SEO

I've got a pretty vanilla OBSD 3.1 box acting as a firewall/router for a
small internal network of two Macs and a Win2K box. xl0 is the inside
device, attached to a switch. xl1 is on the outside attached to a cable
modem.

I'm using the "wakeonlan" Perl script to wake the Macs from sleep so I
can do maintenance, perform updates &etc., but for some reason these
packets are not being sent from the OBSD box.

I can send the same packets from one of the Macs to another Mac, which
works just fine (i.e., both Macs have ethernet cards that support
Wake-On-LAN). Of course, in this case, the magic packets are sent
through the switch, not the OBSD box.

I've done some sniffing with tcpdump, and no traffic related to
wakeonlan seems to hit the internal ethernet device (attached to the
aforementioned switch). If I specify the IP address arg to wakeonlan,
tcpdump reports:

12:16:07.048788 arp who-has 10.0.0.10 tell myrouter.domain.org

Of course, the ARP table does not have any entry for this IP (yet).

Hmm. And I've just found out while testing this as I write, that _some_
variation of IP works -- maybe "10.0.0.255"? Perhaps my firewall is
blocking 255.255.255.255? I _think_ I tried this w/o any PF rules
enabled, but now I'm not so sure.

If anyone can spare a clue, that would be great.

On Fri, 19 Dec 2003 12:27:10 -0500, clvrmnky wrote:

> I've got a pretty vanilla OBSD 3.1 box acting as a firewall/router for a
> small internal network of two Macs and a Win2K box. xl0 is the inside
> device, attached to a switch. xl1 is on the outside attached to a cable
> modem.
>
> I'm using the "wakeonlan" Perl script to wake the Macs from sleep so I
> can do maintenance, perform updates &etc., but for some reason these
> packets are not being sent from the OBSD box.
>
> I can send the same packets from one of the Macs to another Mac, which
> works just fine (i.e., both Macs have ethernet cards that support
> Wake-On-LAN). Of course, in this case, the magic packets are sent
> through the switch, not the OBSD box.
>
> I've done some sniffing with tcpdump, and no traffic related to
> wakeonlan seems to hit the internal ethernet device (attached to the
> aforementioned switch). If I specify the IP address arg to wakeonlan,
> tcpdump reports:
>
> 12:16:07.048788 arp who-has 10.0.0.10 tell myrouter.domain.org
>
> Of course, the ARP table does not have any entry for this IP (yet).
>
> Hmm. And I've just found out while testing this as I write, that _some_
> variation of IP works -- maybe "10.0.0.255"? Perhaps my firewall is
> blocking 255.255.255.255? I _think_ I tried this w/o any PF rules
> enabled, but now I'm not so sure.
>
> If anyone can spare a clue, that would be great.

I'm guessing that Wake-On-LAN only wakes up your Mac if it sees
its own MAC (ethernet) address. If this is the case, your ARP won't get
answered by a sleepy Mac, since they are sent as ethernet broadcast
packets. Try adding your Mac's address to your firewall's ARP table
by using the arp(8) command (as root, of course):

arp -s <Mac's IP> <Mac's MAC>

Then try to send a wakeup packet. If this works, just
add that command to an appropriate rc file on your firewall.

Craig Orsinger wrote:
> On Fri, 19 Dec 2003 12:27:10 -0500, clvrmnky wrote:
>
>
>>I've got a pretty vanilla OBSD 3.1 box acting as a firewall/router for a
>>small internal network of two Macs and a Win2K box. xl0 is the inside
>>device, attached to a switch. xl1 is on the outside attached to a cable
>>modem.
>>
>>I'm using the "wakeonlan" Perl script to wake the Macs from sleep so I
>>can do maintenance, perform updates &etc., but for some reason these
>>packets are not being sent from the OBSD box.
>>
>>I can send the same packets from one of the Macs to another Mac, which
>>works just fine (i.e., both Macs have ethernet cards that support
>>Wake-On-LAN). Of course, in this case, the magic packets are sent
>>through the switch, not the OBSD box.
>>
>>I've done some sniffing with tcpdump, and no traffic related to
>>wakeonlan seems to hit the internal ethernet device (attached to the
>>aforementioned switch). If I specify the IP address arg to wakeonlan,
>>tcpdump reports:
>>
>>12:16:07.048788 arp who-has 10.0.0.10 tell myrouter.domain.org
>>
>>Of course, the ARP table does not have any entry for this IP (yet).
>>
>>Hmm. And I've just found out while testing this as I write, that _some_
>>variation of IP works -- maybe "10.0.0.255"? Perhaps my firewall is
>>blocking 255.255.255.255? I _think_ I tried this w/o any PF rules
>>enabled, but now I'm not so sure.
>>
>>If anyone can spare a clue, that would be great.
>
>
> I'm guessing that Wake-On-LAN only wakes up your Mac if it sees
> its own MAC (ethernet) address. If this is the case, your ARP won't get
> answered by a sleepy Mac, since they are sent as ethernet broadcast
> packets. Try adding your Mac's address to your firewall's ARP table
> by using the arp(8) command (as root, of course):
>
> arp -s <Mac's IP> <Mac's MAC>
>
> Then try to send a wakeup packet. If this works, just
> add that command to an appropriate rc file on your firewall.
>
I tried this with no love. The trick seems to be to send the magic
packet to a broadcast address, but not the default of 255.255.255.255.