[ubuntu-uk] Local IP Address Allocation

[Tony Pursell]

All routers run DHCP (Dynamic Host Configuration Protocol) to automatically
give devices an IP address. Devices are usually set to 'use DHCP' so they
use the IP address given by the router.

Routers will provide for one of two methods of fixing IP addresses.

The simplest (to understand) is to provide a range of IP addresses which
are not used by DHCP.  You can then go to a devices network settings and
allocate it a fixed IP address from this range.  The downside to this is
having to maintain your own record to prevent you allocating the same fixed
IP address to more than own device.

The second method (less easy to understand) is to manipulate the DHCP lease
time.  The lease time governs the period of time for which the router keeps
the same IP address for a particular device.  When it expires, the router
can allocate that IP address back to the same device, or to a different
device.  Some routers allow you to specify that the lease for a particular
IP address never expires.  That effectively fixes the IP address for the
device.  The advantages of this is that you don't have to maintain your own
list if fixed IP addresses and you don't need to change any network
settings on the device (they continue to 'use DHCP').  The Plusnet
Technicolor router, for instance, uses this method.

You will have to find out which methods your router allows you to use.

Tony

On 30 March 2015 at 06:12, Gibbs <linux at danielgibbs.net> wrote:

>
>
> On 29/03/15 23:29, Nigel Verity wrote:
> > Hi
> >
> > Just a minor question about local networking....
> >
> > I routinely have a number of different devices connected to my home
> network such as Ubuntu laptops, iPad, Android phone, Kindle, RPi and so on.
> The router allocates local IP addresses to them as and when they connect.
> Although those IP addresses are always within a very narrow range
> (192.168.1.1 -> 12) they are not fixed.
> >
> > Is it normally possible to set a general purpose router to recognise a
> given device and always allocate the same local IP address to it?
> >
> > Thanks
> >
> > Nige
> >
> >
>
> If your router doesn't provide you the option this can done with DHCP.
>
> Some links that might help from a quick google.
>
> Android -
>
> http://acer.custhelp.com/app/answers/detail/a_id/11130/~/how-do-i-set-a-static-ip-address-in-the-android-operating-system%3F
>
> iPad - http://osxdaily.com/2012/05/19/manual-dhcp-static-ip-address-ios/
>
> RPi -
>
> http://thepihut.com/blogs/raspberry-pi-tutorials/16683276-how-to-setup-a-static-ip-address-on-your-raspberry-pi
>
> Kindle - http://www.howtofixanything.co.uk/howto-kindlestaticip.html
>
> Gibbs
>
> --
> ubuntu-uk at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk
> https://wiki.ubuntu.com/UKTeam/
>
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