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1.1. Frequently Asked Questions (FAQs)
1.2. Questions we're working on
These are the questions we're working on - if you can help please do get in
- How do I enable "wake-on-LAN" on a desktop computer?
- Not all computers can be woken using the WOL service, and some
computers are capable but have wake-on-LAN disabled. Wake-on-LAN can be
enabled by changing a computers BIOS settings. Exactly how this is done
varies between different models of computer. Energy Star provide an
introduction to enabling wake-on-LAN on desktop computers.
- Does turning a computer off each day make it more likely
that a component will fail?
- The computing service department at Oxford University can find no
evidence to support this idea. Over a hundred classroom and Help Centre
desktop computers have been turned on and off on a daily basis for the
last five years, without there being any evidence that components are
failing as a result.
- How do I switch computers into low-power states?
- There are many ways to switch desktop computers into low-power states:
(a)manually switching a computer off, or into sleep (S3) and
hibernate(S4) power-saving modes, (b) configuring sleep (S3) and
hibernate (S4) so the computer and monitor automatically enter low-power
states after a period of inactivity , (c) logging into a computer
remotely, for instance using a 'remote desktop' type application, and
shutting it down e.g. using the DOS command "shutdown -s", (d)
installing a script such as PowerDown, developed at Liverpool
University, to automatically switch computers off after a specific
period of time if nobody is logged in.
- Are there commercial service that support improved desktop
- Yes. EnergyStar have created a list of commercial services that support desktop power management
initiatives. Like EnergyStar the computing service can offer
no advice on the suitability of these service within departments and
colleges at the University.
- Is it more efficient to leave a computer on all the time,
rather than boot it each morning, because booting computers uses so much
- No. Booting a computer may raise the power that a computer is running
at by a few Watts for around 90 seconds but the extra energy consumed is
insignificant compared to the energy that will be consumed if left on
- Are other educational organisations undertaking similar
- Yes, here we list a few examples:
- What do I need to do to install a gateway server 'behind' a
- The gateway can be set up to turn on computers on a private network,
behind NAT. In order to allow this, certain requirements have to be
- the gateway needs to be a part of the private network
both physically and logically
- NAT has to be configured to enable
port forwarding to the gateway IP on port 8443 (any inbound packet sent
to the public IP address of the NAT has to be forwarded on port
- it is essential, that the DNS name on the certificate for
the gateway matches the DNS name of the public IP address of the
- How do I turn my computer off remotely e.g. when away at a
conference or from home?
- In case the usual route of turning your computer off remotely didn't
work on your Windows machine, you can go to Start -> Run and issue the
command: "shutdown.exe -s". You will be prompted with a warning and the
system will take 30 seconds to shut down. You can create a shortcut to
the command and put it on the desktop, to make the shutdown process
quicker and easier. On Linux machines, issue the following command to
turn the computer off: "shutdown -h now"
- I think that my local firewall is blocking the WOL packets,
as my computers never wake up. How can i help this?
- If you use a local firewall within the WOL subnet, it may stop the
magic packets in circulating and waking computers up. In order to
address the problem, make sure, that the firewall is set to allow UDP
traffic on port 9 originating from your WOL gateway.
- I installed the Linux-based gateway VM image in my Virtual
Infrastructure, but can't connect to it via SSH. Can you help?
- The Linux VM images have very tight security and by default, all
incoming connection are blocked. In order to allow incoming SSH
sessions, edit the following files allowing connections to port 22 from
your management IP:
/etc/init.d/iptables. This article explains how to use iptables to get the desired
- Can WoL work on a VMPS network?
- WoL and Dynamic VLANs are not compatible because when the PC is shut
down, the NIC will be powered down for a split second. This causes the
switch to detect the link-down event and to un-assign the port. When the
NIC comes back online, the port does not belong to any VLAN and since no
frames are received by the port, it would never initiate VMPS queries or
forward broadcast/multicast to the device connected to it.
- Are there any known conflicts with other software?
- We have discovered, that FiDo software causes conflicts when run alongside of Altiris and VMware software. The conflict is related
to ports - Altiris and VMware use the same ports as the gateway
software. To avoid running into such problems, we advise to designate a
separate computer to act as FiDo gateway.
- Is it possible to set up scheduled wake up for multiple computers/devices?
- A scheduled wake up of multiple computers can be achieved - computers/devices have to be added to a group first, using the ITSS Wake-on-LAN pages available here.