Re: [Xen-users] ip which is already being used can be taken by windows vps

[Simon Hobson <linux@xxxxxxxxxxxxxxxx>]

Jingyun He wrote:

> I just noticed that the windows vps can take any IP that is already
> being used in the network,
> e.g. one other server is using 1.1.1.1, and another vps in the network
> just assign that IP, and activate it, then the ip 1.1.1.1 will connect
> to vps, and the server will lose connection.
Just to make the point here that no-one else has mentioned - this is 
no different under Xen than when running standalone machines. In 
general, the prevention (management systems) and mitigation 
techniques (eg ARP monitoring) are the same - but as others have 
pointed out, you have a couple more options (eg source IP filtering) 
with Xen guests which aren't available on most 'real' network 
switches.
We had our office network go down on us a few weeks back when someone 
was playing with his new Windoze mobile phone - in particular the bit 
that turns it into an access point (connects to internet over GPRS, 
shares it via wireless). Trouble is that he was connected to the 
office wireless and it came up with the same IP address as our 
router. We've also had customers taken out when someone (without 
thinking or asking) set up a device on our public net on an address 
assigned to a customer - he hasn't been allowed to forget it, and we 
now have ARP monitoring in place.
--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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