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Why does the network manager relink for IP changes

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Andrew Habgood

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Sep 21, 2000, 3:00:00 AM9/21/00
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If I change the IP address of my NIC with the Network Manager, it requires a
relink. However I can use ifconfig without one. Does the Network Manager
do anything differently? Besides leaving the old ip in /etc/hosts ;-)


Tony Lawrence

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Sep 21, 2000, 3:00:00 AM9/21/00
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One reason for the relink (and it may be the only reason, I
dunno) is so that the low-level kernel routines know the
machines IP address- if you've ever pinged an OSR5 or UW
server while they were in single user mode, you will have
noticed that it responds- without tcp/ip running, and to do
that it would need to know its address.


--
Tony Lawrence (to...@aplawrence.com)
SCO/Linux articles, help, book reviews, tests,
job listings and more : http://www.pcunix.com

Bill Vermillion

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Sep 21, 2000, 3:00:00 AM9/21/00
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In article <39CA0155...@aplawrence.com>,

Tony Lawrence <to...@aplawrence.com> wrote:
>Andrew Habgood wrote:

>> If I change the IP address of my NIC with the Network Manager, it
>> requires a relink. However I can use ifconfig without one. Does
>> the Network Manager do anything differently? Besides leaving the
>> old ip in /etc/hosts ;-)

>One reason for the relink (and it may be the only reason, I
>dunno) is so that the low-level kernel routines know the
>machines IP address- if you've ever pinged an OSR5 or UW
>server while they were in single user mode, you will have
>noticed that it responds- without tcp/ip running, and to do
>that it would need to know its address.

Let's hope this changes. I can change IP's in other Unix systems
and routers with no reboot/restart. No reason to have to rebuild a
kernel for something a minor as an IP change IMO.

I can put in an alias in a Cicso router or some Unix systems, remove
the the first address, and the alias is now the first address.
This happens in real-time. A quick clear of the arp table will
clean up anything rapidly - that will other wise heal themselves
as the arp entries age.

Saving the changes to a config file means that these changes will
now be there on a reboot. Jeff's instructions on changing IP
numbers as well as system names/information which is stored in SO
MANY locations - really shows that this old behavior needs to
change.

Bill
--
Bill Vermillion - bv @ wjv . com

Scott Neugroschl

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Sep 21, 2000, 3:00:00 AM9/21/00
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It's because of the "kernel slink" module (ksl). For efficiency
reasons, SCO put the slink module (which builds the TCP/IP STREAMS
stack)
into the kernel. This can be disabled using ksl.disable in the
bootstring.
Of course, if you want, you can use ifconfig to change addresses, it
just won't be
permanent.

Personally, I thought this was a stupid decision, myself.

Tony Lawrence wrote:
>
> Andrew Habgood wrote:
> >
> > If I change the IP address of my NIC with the Network Manager, it requires a
> > relink. However I can use ifconfig without one. Does the Network Manager
> > do anything differently? Besides leaving the old ip in /etc/hosts ;-)
>
> One reason for the relink (and it may be the only reason, I
> dunno) is so that the low-level kernel routines know the
> machines IP address- if you've ever pinged an OSR5 or UW
> server while they were in single user mode, you will have
> noticed that it responds- without tcp/ip running, and to do
> that it would need to know its address.
>

Evan Hunt

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Sep 21, 2000, 3:00:00 AM9/21/00
to

Don't blame me, I voted for Scott Neugroschl <sco...@pacbell.net>.

>It's because of the "kernel slink" module (ksl). For efficiency
>reasons, SCO put the slink module (which builds the TCP/IP STREAMS
>stack) into the kernel. This can be disabled using ksl.disable in the
>bootstring.

Well, far be it from me to speak ill of netconfig. If I were to say
that netconfig bites, the statement would, to me, be the moral equivalent
of volunteering to be the one to wade in there and fix it. So let me be
very clear on this right from the start: Netconfig is just *wonderful*
the way it is. All hail netconfig.

However: slink has nothing to do with configuring IP addresses, and so
there's no reason for a kernel relink. This is just netconfig being...
um... perfect in its own special way.

>Of course, if you want, you can use ifconfig to change addresses, it
>just won't be permanent.

The permanent storage of the IP address is in /etc/tcp, a shell script
which netconfig--glorious, *visionary* utility that it is--uses awk to
modify whenever you change your TCP configuration. You can change the
address by hand by editing /etc/tcp yourself (along with /etc/hosts and
all the other files Jeff Lieberman has identified elsewhere) and no
relink will be necessary.

Or, you can just click "No" when netconfig asks if you want to relink the
kernel; as long as you haven't changed your NIC, or added a new WAN
interface, you'll be fine.

--
Evan Hunt - evanh at sco dot com

"I have always wished my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone."
- Bjarne Stroustrup

Jeff Liebermann

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Sep 21, 2000, 3:00:00 AM9/21/00
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On 21 Sep 2000 23:09:58 GMT, ev...@sco.COM (Evan Hunt) wrote:

>Well, far be it from me to speak ill of netconfig.

Netconfig doth suck. However, since I'm the worlds worst programmist,
nobody is gonna stick me with trying to fix it. Therefore, it's safe for
me to say it doth suck.

>The permanent storage of the IP address is in /etc/tcp, a shell script
>which netconfig--glorious, *visionary* utility that it is--uses awk to
>modify whenever you change your TCP configuration. You can change the
>address by hand by editing /etc/tcp yourself (along with /etc/hosts and
>all the other files Jeff Lieberman has identified elsewhere) and no
>relink will be necessary.

Hey. Pleeze spel me naime correctish. There are two "n" at the end.

See:
http://www.cruzio.com/~jeffl/sco/new_name.txt
for the shopping list of files containing either the IP address, the
system name, or both.

My guess(tm) is that netconfig reads ALL the parameters on the netconfig
menu and does NOT test if anything has changed on exit. Since the system
name is imbedded into the kernel, a relink is appropriate (ignoring that
uname -S newname can do it without a relink by patching the kernel).


--
Jeff Liebermann je...@comix.santa-cruz.ca.us
150 Felker St #D Santa Cruz CA 95060
831-421-6491 pager 831-429-1240 fax
http://www.cruzio.com/~jeffl/sco/ SCO stuff

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