Re: Wireless handhelds
- From: david20@xxxxxxxxxxxxxxxx
- Date: Fri, 18 Aug 2006 12:11:36 +0000 (UTC)
In article <h93be25bqa9646l07nj8l2ha80sn6isad3@xxxxxxx>, David Gray <police@xxxxxxxxxxx> writes:
Basically all you should need are a number of wireless access points spread
Hello all,
Alpha server ES45
OpenVMS 7.3-2
Powerhouse 710G1
We are just starting to look at proof of concept that would allow us
to use wireless handheld devices with our VMS systems. By handheld I
mean warehouse scanning units from manufactures such as Symbol
technologies running a VT emulator.
I worked for a company 8 years ago who implemented a similar setup for
their warehouse with the handheld units connecting via telnet and
logging in directly to the VMS system, new screens were written to use
the small screen area. Unfortunately I was not involved in any of the
hardware side of things so I'm not sure how that bit worked.
around the warehouse which will allow the handheld devices to connect onto the
same network as the VMS system.
The complications come in making sure you have
1) Adequate coverage without adjacent access points interfering with each other
There are three wireless standards 8.2.11b,802.11g and 802.11a.
802.11b uses the same frequencies in the 2.4GHz range as 802.11g but is
slower and an older standard.
Most modern equipment should now support 802.11g.
Unfortunately b and g rather restrict the channels which can be used since
although they specify upto 14 channels (the exact number varies according to
which country you are in) the channels overlap so that in reality you can only
use about 3 channels without overlap. Generally you want adjacent access points
to be using different non-overlapping channels.
(There are now some systems available which will automatically detect adjacent
access points and will try to switch channels and alter their power levels to
minimise interference which simplifies deployment)
The 802.11a standard uses a different frequency (5GHz) to b and g and offers
a much larger number of non-overlapping channels. However equipment tends to
be more expensive and there may be more restrictions on its use in some
countries. Also has a shorter range than 802.11b/g so requiring more access
points to cover a given area.
2) Providing adequate security of the wireless communications
The original wireless standard was WEP. This proved to be shockingly easy to
break. So unless you run further encryption over it by requiring VPN usage
then it is best to use devices which support the newer WPA or WPA2/802.11i
security.
WPA can be run in two modes
1) WPA-PSK which uses a pass-phrase to generate keys
and is only really recommended for home use - if you do use it then make sure
the pass phrase is at least 20 characters long since programs have been
produced which can launch a successful dictionary attack against smaller
pass phrases.
or
2) WPA with 802.1x authentication.
This will require you to setup a Radius server on your network which
supports a protocol called EAP and one of various EAP authentication
protocols. PEAP can just require the use of passwords whereas other
protocols may require you to use certificates and setup a PKI
infrastructure.
David Webb
Security team leader
CCSS
Middlesex University
Has anyone got a system such as this who could give me pointers on.
what hardware I would need to buy in order to allow wireless access to
the VMS systems? Any pitfalls or recommendations on hardware
manufactures.
The warehouse is located at the same site as the VMS system.
Thanks in advance
Dave.
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- From: David Gray
- Wireless handhelds
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