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15

Sending a single packet and waiting for a response is going to be one of the fastest possible ways, and ping is a fine way to do that. In fact, depending on your use case, I'd argue that it's too fast, since it doesn't really tell you if the system is actually doing anything useful, just that the kernel's network subsystem is alive and configured. But ...


10

I have had luck using PowerNap (it is packaged for ubuntu-sever, but the source is there so you should be able to compile it on anything) to suspend backup machines when they aren't doing anything. However, this won't wake them up automatically. There is also a PowerWake program bundled with the PowerNap source tarball (packaged as powerwake in Ubuntu) ...


8

You might have better luck using the tool arping instead. The tool ping works at the layer 3 level of the OSI model, whereas arping works at layer 2. You still need to know the IP of the system however with this tool. There are 2 versions of it, the standard one included with most Unixes (Alexey Kuznetsov's) is the version that can only deal with IP ...


6

socat is a killer utility. Put somewhere in your init scripts: socat -u -T1 UDP-LISTEN:1234,fork UDP-DATAGRAM:255.255.255.255:5678,broadcast Some users have problems with UDP-LISTEN, so using UDP-RECV seem better (warning: could send the broadcast packets in an endless loop) socat -u UDP-RECV:1234,fork UDP-DATAGRAM:255.255.255.255:5678,broadcast fork allow ...


6

OS X can do this now, as of Snow Leopard. It's made possible through the Sleep Proxy Service. It's pretty much automatic. The only requirement is that you have a second always-on Apple device on your LAN that can act as the sleep proxy. Their current low-power embedded boxes all support this, I believe: Airport, Time Machine, and Apple TV. In the ...


4

The ether-wake command will work by mac address, so surely you a) wont need an IP address and b) can send the command without harm (if it's already awake, waking it will have no impact?) You can see the list of your existing arp cache by using arp -an and grepping for your MAC to get the IP of the target host. However, because arp is a cache it may have ...


4

You need something that's capable of sending an Ethernet packet that will be seen by the device you want to wake up. The ether-wake command in BusyBox is exactly what you're after. If your BusyBox doesn't have it, consider recompiling BusyBox to include it. If you have a sufficiently “bloaty” netcat (BusyBox can have one of two nc implementations, one of ...


2

What you could do it ping the broadcast address which should cause all the computers to ping back. Then you could cross check this list against what you have in SQLite to ensure all the computers are up. Other then that a ping is probably the fastest way to ensure a computer is awake on a network. As mentioned by the other answer this doesn't provide any ...


2

Wake on LAN is a BIOS and NIC feature, not an OS feature, that is, you need a supporting BIOS and NIC to do it. Once you've enabled it in your BIOS (if you can), you can check if your NIC has WOL support enabled by checking the output of ethtool [interface]. If the value of Supports Wake-on contains g, your NIC supports WOL magic packets. To check if it ...


2

I found this question on Serverfault. I didn't manage to get such broadcast traffic through my router though. The DNATted packets didn't even arrive at my FORWARD chain. Maybe there is some strange kernel option which disallows that. But the ARP idea is interesting. I guess that should be accompanied by a rule in OUTPUT which forbids packets to this ...


1

The most probable reason for this error is that the Getopt/Std.pm library is damaged on your system. Try to locate it, for example with locate Std.pm; on my system, it's located here: iserv ~ # locate Std.pm /usr/share/perl/5.10.1/Getopt/Std.pm Try to open it with an editor. It is 295 lines long on my system and it has to end with the line 1;. If the file ...


1

Manually testing using etherwake I think you can test it using a tool like etherwake. Depending on the distro it's called etherwake on Ubuntu/Debian, ether-wake on RHEL/CentOS/Fedora. I had it installed already by default on Fedora, it's part of the net-tools package. To use it: # Redhat $ ether-wake 00:11:22:33:44:55 # Debian/Ubuntu $ etherwake ...


1

Unless your network hardware preserves some state based on the WOL wakeup, that you can read after the initialisation during the boot process, you cannot determine this. I have not looked at WOL in detail since 2000, but the network cards I worked with at that time certainly did not have such a feature.


1

Here are a couple of easy ways for your server to check if other devices are using it: Check the arp cache using /usr/sbin/arp or by reading /proc/net/arp. You'll see in there all the devices which the server has communicated with fairly recently. This includes the MAC address, so you can find your phone, etc. even in the face of DHCP. Use ping (or arping, ...


1

/dev/udp is recognized by bash and doesn't really exist in the filesystem, so give it a try. I think you can use syslogd without -l switch, as long as it supports -R. I have busybox with syslogd withount -R, no nc nor bash and I'm still stuck.



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