08 Jan Offsite Detection
When measuring the power usage of laptops we need to consider the question of where the laptop is located at any point in time and hence who’s power is being used to power the device. The offsite detection feature allows you to configure the eiPower agent to determine when a laptop is On-site (that is, operating within your organisation’s buildings) or Off-site (such as when someone takes their computer home to do some work)
When the Off-site detection feature is enabled and configured the eiPower agent includes an On/Off site status on each power event sent to the server. Each of the eiPower saver reports contain a parameter that allows you to specify whether you want the report to include or exclude Off-site power events.
Offsite detection is configured by specifying one or more IP address ranges that contain all the IP addresses used in your organisation. For example, if your organisation uses the following subnets :
Then you would specify the following address ranges as your On-site address ranges:
220.127.116.11 – 18.104.22.168
22.214.171.124 – 126.96.36.199.255
Whenever a computer’s IP address lies within one of these ranges then the computer is considered On-site, otherwise it is Off-site.
Notice that it is not necessary to specify an IP address range for each subnet in your organisation, it is only necessary to specify ranges that cover all the IP addresses. Additionally it does not matter if you specify IP ranges that cover a few IP addresses not used by your organisation – these will have no affect on the Offsite detection.
The eiPower agent only checks the IP address of the computer’s ethernet and wireless network adaptors – all virtual adaptors are ignored. This ensures that a laptop that is connected via VPN to an organisation’s network is not considered On-site.
The use of IP Address ranges to determine On/Off site status is a simple and effective mechanism for performing Offsite detection that does not introduce any addition network traffic.
Issue with use of Private IP Ranges
An issue can arise when an organisation uses the same IP address ranges that are typically used by home networks. In these situations, care must be taken when configuring Offsite detection to ensure that the eiPower agent does not incorrectly report devices as being On-Site when they are being used from someone’s home or a public internet location.
The default configuration for your typical home modem/wireless device issues IP Addresses starting from either 192.168.0.1 or 10.0.0.1. Hence when a user is using their laptop at home they will generally have an IP address in the following ranges :
192.168.0.1 -> 192.168.0.10
10.0.0.1 -> 10.0.0.10
When the eiPower Offsite detection is configured is it important not to specify an IP Address range that includes the above IP address as doing so will cause the eiPower agent to report a computer as being On-site when it is actually being used from a user’s home. Although there may be a few On-site computers that have an address in the above ranges which will get incorrectly reported as Offsite, these will be very small in number and will have a minimal affect on the report results.
Offsite Detection Changes in Adelaide Update 2
One of the major features in the Adelaide Update 2 release is an extension to the Offsite detection feature so that the eiPower agent is able to use the computer’s DNS server as well as its IP address when determining if a computer is On/Off site.
The Offsite Detection Policy page has been updated to allow you to specify a list of DNS server addresses as well as the list of IP address ranges.
The agent have been updated to use the follow algorithm to determine if a computer is On/Offsite :
If the computer has no active ethernet or wireless adaptors then the computer is ON-SITE
Otherwise if one or more DNS addresses have been specified and the DNS address of the computer’s ethernet or wireless adaptors is NOT in the list of DNS addresses then the computer is OFF-SITE
Otherwise if one or more IP address ranges have been specified and the IP address of the computer’s ethernet or wireless adaptors is NOT within one of the IP address ranges then the computer is OFF-SITE.
Otherwise the computer is ON-SITE