[nos-bbs] IP config for tun device

[George (Skip) VerDuin]

Hi all,

Truthfully - I feel really naive in asking this next question.
I have not sorted out for myself a model for IP ownership - is it a) the
stack, or b) the terminus of the link, or c) something else?
As far as I have gotten is that it may be a mixed bag, and I now
consider the stack as default (or "native") and the terminus as an
alias.
Clearly a stack can support multiple IP identities in the stack as is
appropriate to gateway applications, my quandary is to understand when
it SHOULD.
My "Bible" on net subject "TCP/IP Network Administration" by Craig Hunt
is not answering me...

Take tun configuration as a jnos example.
Maiko and I had significant conversation a long time ago that resulted
in:
[host ip 192.168.1.32]
[autoexec.nos:
ip address 44.102.132.20
ifconfig tun0 address 192.168.2.1
shell ifconfig tun0 192.168.1.249 pointtopoint 192.168.2.1 ...]
adopted as a go-by for configuration.
It works just fine - it introduces two "alias IPs".

On the other hand tun may successfully be configured as:
[host ip 192.168.1.32]
[autoexec.nos:
ip address 44.102.132.20
ifconfig tun0 address 44.102.132.20
shell ifconfig tun0 192.168.1.32 pointtopoint 44.102.132.20 ...]
This configuration uses the "default IP' on each end of the tun device.
Both stacks do get the appropriate route configurations and ping works
fine.

So: what breaks when you use the "native IP" of the stack as the
terminal IP of tun?
Is the deciding factor for the multiple IPs duplication of socket
functions?
With one stack on the DOS platform this seems like a need so that two
"telnets" can be supported on one socket ID.
However duplication is less a factor with the multiple stack
architecture of the Linux platform jnos application.

I'm looking specifically at application of the tun device (Maiko's
baby?) with jnos - that's true.
But I'm also wanting a piece of network wisdom when all is said and
done...
Is this a question someone on nos-bbs can quickly address - OR - is
there a reference document that treats this subject cleanly?
Thanks in advance for light you shed on this confusion!

73
de Skip k8rra k


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