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Groups > linux.debian.user > #193020

Re: stretch and DNS name resolution service for other devices on a LAN

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Le 22/02/2018 à 22:57, David Wright a écrit :
> On Tue 23 Jan 2018 at 20:56:31 (+0100), Pascal Hambourg wrote:
>> Le 23/01/2018 à 18:08, David Wright a écrit :
>>>
>>> [My Laptop] --- wireless connection IPv4 --- [Router] --- Internet Modem
>>>       |                                         / |
>>>       | CAT5 cable IPv6                        /  |
>>>       |                                       /   | wireless/wired
>>> [My Desktop] --- wireless connection IPv4 __/    | connections
>>>                                                   | IPv4
>>>                                                   |
>>>                                                  [TVs]
>>>
>>>> Both devices will allocate themselves an address in the 'link local' range,
>>>> and these addresses can then be used for communicating between the devices.
>>
>> They can, but they should not be used with application-layer
>> protocols. Really. IPv6 link local addresses are not meant for this.
> 
> Well, I won't argue with this as I don't know what they were
> originally meant for.

They are meant to be used with low level IPv6 services (automatic 
configuration, neighbour discovery...)

> However, I don't see why I have them if I'm
> not allowed to use them when I find a good reason to. I didn't pay
> good money just to stare at the numbers in  ip address show.

You did not pay any money for IPv6 link local addresses.

>> On disadvantage is that these addresses are not globally unique (the
>> link local prefix exists on all interfaces) and must be appended
>> with an interface name.
> 
> Not an issue here. The only change I have made since you commented
> on this in August 2016 is that I now sed the output of
>      ip -o link show
> to pick up the name of the ethernet interface. (The file that defines
> my IPv6 functions is shared with wheezy/jessie/stretch hosts, and
> "eth0" doesn't cut it any more.)

Hackish.

>> The second disadvantage is that if the
>> interface is replaced for whatever reason, the interface name may
>> change and the MAC address will change. The link local addresses is
>> based on the MAC addresses, so it will change too.
> 
> Well, as the MAC addresses are all configured in my router,

No, A MAC address is configured in the ethernet adapter NVRAM. Besides, 
The two interfaces we are discussing about are not connected to any router.

>> IMO, simple
>> static configuration with a ULA prefix, or with a global prefix if
>> you own one, would be much reliable.
> 
> So what would be involved in setting that up? I have no idea where
> to start. I can't believe it's as simple as 1,2,3 below.

Get a ULA prefix. Online generators are available on the web.
Pick up two host addresses in the prefix.
Statically assign an address to the two interface in 
/etc/network/interfaces or any other network manager.

>> So Andy is right : you could use IPv4 for this. But rather with
>> static configuration than unpredictable APIPA assignments.
> 
> Of course I could, but then I've got to interfere with the routing
> table to prevent the file transfers going through the default
> wireless interface.

You can't be more wrong. With the static configuration of a pair of IPv4 
addresses in a distinct prefix at both ends of the ethernet link the 
traffic between these addresses would flow through the ethernet link.

> If I use IPv6, this is all I have to do to transfer large files at
> CAT5 speeds:
> 
> 1) plug a CAT5 cable into ethernet ports at each machine,
> 2) on the source, type:   <TargetHost>6 <filenames>
> 3) when finished, remove the cable.
> 
> The wireless interface is unaware of any change, so I can still use
> the WAN, or even connect to the other host through its normal wireless
> route and, say, initiate transfers in the opposite direction (which
> has the advantage that such a connection stays up after the cable has
> been removed).

Same with IPv4.

Anyway, we have a saying here which roughly translates to : "you cannot 
force an unthirsty donkey to drink".

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Thread

stretch and DNS name resolution service for other devices on a LAN "D. R. Evans" <doc.evans@gmail.com> - 2018-01-18 22:40 +0100
  Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-18 22:50 +0100
    Re: stretch and DNS name resolution service for other devices on a  LAN "D. R. Evans" <doc.evans@gmail.com> - 2018-01-19 06:20 +0100
      Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-19 21:10 +0100
  Re: stretch and DNS name resolution service for other devices on a  LAN Greg Wooledge <wooledg@eeg.ccf.org> - 2018-01-18 22:50 +0100
    Re: stretch and DNS name resolution service for other devices on a  LAN "D. R. Evans" <doc.evans@gmail.com> - 2018-01-19 06:20 +0100
    Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-19 12:50 +0100
      Re: stretch and DNS name resolution service for other devices on a  LAN john doe <johndoe65534@mail.com> - 2018-01-19 13:10 +0100
        Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-19 13:30 +0100
          Re: stretch and DNS name resolution service for other devices on a  LAN Michael Stone <mstone@debian.org> - 2018-01-19 15:10 +0100
            Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-19 15:30 +0100
      Re: stretch and DNS name resolution service for other devices on a  LAN Greg Wooledge <wooledg@eeg.ccf.org> - 2018-01-19 14:50 +0100
        Re: stretch and DNS name resolution service for other devices on a  LAN Michael Stone <mstone@debian.org> - 2018-01-19 15:10 +0100
        Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-19 15:20 +0100
          Re: stretch and DNS name resolution service for other devices on a  LAN Rob van der Putten <rob@sput.nl> - 2018-01-19 16:20 +0100
            Re: stretch and DNS name resolution service for other devices on a  LAN Michael Stone <mstone@debian.org> - 2018-01-19 17:40 +0100
            Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-19 20:40 +0100
        Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-01-19 16:20 +0100
          Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-22 18:30 +0100
            Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-01-22 23:30 +0100
              Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-23 10:30 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Curt <curty@free.fr> - 2018-01-23 12:20 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Joe <joe@jretrading.com> - 2018-01-23 14:50 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-01-23 15:50 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Andy Hawkins <andy@gently.org.uk> - 2018-01-23 17:10 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-01-23 18:10 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-01-23 21:00 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-02-22 23:00 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-02-24 10:00 +0100
                Re: stretch and DNS name resolution service for other devices on a   LAN Curt <curty@free.fr> - 2018-02-24 11:10 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-02-25 18:40 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-02-27 21:00 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-02-28 18:20 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-02-28 19:50 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-02-28 21:20 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-03-03 00:00 +0100
                Re: stretch and DNS name resolution service for other devices on a  LAN David Wright <deblis@lionunicorn.co.uk> - 2018-03-04 20:30 +0100

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