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Re: [K12OSN] Access to K12LTSP remotely

Stephen Liu <satimis icare com hk> wrote:

The broadband provider only gives a
dynamic IP which will change at X-hour internal.  It happens on K12LTSP
as well as fat-client sides.  If the K12LTSP or the fat-client relogin
another dynamic IP address will be assigned.  Say for example;

Dynamic IP address of K12LTSP = aaa.aaa.aaa.aaa

Shall I issue following commands on fat-client side

1) ssh -X user aaa aaa aaa aaa
2) application &

How about after X-hours the IP address of K12LTSP changes to
bbb.bbb.bbb.bbb ???  Then the connection will be broken.  Also what will
happen if the fat-client changes its IP address.

Stephen, the problem is not so much a technical one as a marketing/people
one. The ISP knows that by changing the IP address of your machine (the
K12LTSP box in this case) your connections will be broken. That's *why*
they do it. I'll bet they also offer a higher-priced service that offers a
static, unchanging IP address, and if you want to run servers that's the
one they want you to use.

A lot depends on the value of 'X' in your description above. If it's one
hour, then the ISP has got you over a barrel. If it's 672, then the address
changes once a month, and you might be able to live with that, considering
it a minor disruption. In practice, most users of ADSL and similar
broadband services typically find that their IP address does not change
particularly frequently - in some cases, only when the ADSL modem is
recycled, or every few months otherwise.

The advice gave Chris gave you to investigate dyndns, etc. is good. This
will deal with the problem of the IP address of the K12LTSP box changing,
as the dynamic DNS will update to the correct value immediately. Of course,
this depends upon the IP address being allocated to an interface on the
K12LTSP box, and not to the external interface of your broadband modem.
This is the case if you are running PPPoE, for example, and the modem is
configured as a bridge, but not necessarily if the ADSL connection is PPPoA
(PPP over ATM). In the latter case, the modem will get a new address, and
your K12LTSP box will be unaware of it, so that it will not run the
required script to update the dynamic DNS.

For some understanding of the issues involved, and another approach to
implementing dynamic DNS, see this article I wrote some time ago:


I hope this helps. . . .


--- Les Bell, RHCE, CISSP

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