HELP! iMac, cable modem won't go. - Page 6

NTLVictim · 23-02-2007, 09:39

Stripes, while you're waiting for the router to turn up, have a read of this Belkin Manual particularly page 30..your manual maybe slightly different, but it'll give you an idea.

stripes · 23-02-2007, 11:06

So...

ntlvictim. Thanks for that reference, I'll have a look in a minute.

Mark. Now, maybe progress.
On the iMac, with the ethernet disconnected from the modem, I have just entered the modified sudo string, and, BEARING IN MIND THAT I DON'T KNOW WHAT I'M LOOKING AT OR FOR!, in the data that's come back, under en0:, the 'ether' line does now read just the same as the hex string I just put in.

So, if that means that the iMac now has the same address as the G3, will this fool the modem?

Only way to find out is to replug and try it, so I'll be back in a few minutes.

Allen.

melevittfl · 23-02-2007, 11:10

Quote:

Originally Posted by stripes

Only way to find out is to replug and try it, so I'll be back in a few minutes.

The suspense is killing me.

The cable system uses that identifier to uniquely identify the devices on the network. There is a limit to the number of devices that the cable system will allow to connect. When a machine starts up, it asks the cable system for an IP address to use and, the cable system uses the ethernet id to track which machine has which IP address.

It's supposed to allow two devices without having to wait for one to timeout, and even so, leaving the cable modem off for 20 hours (as you mentioned you tried) should have cleared any pre-existing entries.

The theory we're working on is that somehow that's not happening and the cable modem only wants to assign an IP address to the ID used by the G3. By telling the iMac to pretend it's got the same ID as the G3, we're testing out theory.

Cheers,
Mark

stripes · 23-02-2007, 11:49

Mark: sorry for the time it takes - apart from pulling cables in and out, the G3 takes ages to boot up, and if I have been a bit too speedy, has to be rebooted etc.

So, no go again, I'm afraid.

Having got that hopeful ether set of figures the first time, once I connected the iMac to the modem and rebooted everything, still 169.

I tried ifconfig at that point, and sure enough, the ether figures are no longer the ones I put in 45 mins ago for the G3, they are a different set entirely, which I don't recognise.

I then tried the sequence that Dark had recommended, i.e. manual dhcp, apply, dhcp, apply, but still no go. I test the machine at that point in 2 ways - one, seeing what address is returned on Apply Now or Renew DHCP lease, and noting it (although it always starts with 169), two, launching Safari (browser) just to make sure I'm really not connected to Internet.

And the sodding router hasn't turned up. Which probably means tomorrow morning, as we tend only to get van deliveries in mornings. Ah well.

I also pulled the coaxial out of the STB, just in case, but no difference, except I couldn't watch Judge Judy.

I still the like the idea of making my iMac have the same name as the G3, but that route doesn't seem to have done it.

More later, hopefully...

Allen.

---------- Post added at 12:49 ---------- Previous post was at 12:42 ----------

ntl victim: just had a v.quick glance at the Belkin link, and yes, that's why I'm thinking on these lines.

You set up the router with the G3 details, and it's happy. You then stick in the iMac ethernet line, and the modem/router combination doesn't care about another machine's address, only that precious first G3 address.

That's what I'm hoping for! (With my luck, I shouldn't still be an optimist).

I'll report back when something happens.

Allen.

melevittfl · 23-02-2007, 11:51

Quote:

Originally Posted by stripes

Having got that hopeful ether set of figures the first time, once I connected the iMac to the modem and rebooted everything, still 169.

I tried ifconfig at that point, and sure enough, the ether figures are no longer the ones I put in 45 mins ago for the G3, they are a different set entirely, which I don't recognise.

OK, it might reset them when it reboots.

So, give it one more try (if you're not sick of it. )

This time, plug the ethernet cable into the iMac and power on the cable modem and then the iMac, let it boot. THEN, try the ifconfig command to change the id to the one on the G3.

Cheers,
Mark

Dark Fiber · 23-02-2007, 11:55

Quote:

Originally Posted by stripes

I then tried the sequence that Dark had recommended, i.e. manual dhcp, apply, dhcp, apply, but still no go.

Allen.

Sorry to be pedantic- you do mean manual ip, apply etc. ?

There is a (rather dated) procedure from Apple <http://docs.info.apple.com/article.html?artnum=106879>
that involves resetting the interface. Again a typical change-it then change-it-back tactic that goes back at least to when I started using Macs in 1987

I've nailed my colours to the mast:
"Mac enthusiasts want to be shielded from the awesome power of Unix by the Mac GUI. If we can't solve this without "sudo" then we're in deep trouble!"

The tactics I advocate talk directly to the Unix layer but do so via the Mac OS X GUI, leaving less room for error.

BTW why are you still on 10.4.7?
NB It would be v.informative if the router worked _without_ being cloned with a machine MAC

NTLVictim · 23-02-2007, 11:59

Just found this; "Some say it doesn't work because it doesn't change the MAC in the GUI, and because it reverts after a restart..."

Is this true?

parky · 23-02-2007, 12:04

Quote:

Originally Posted by Dark Fiber

BTW why are you still on 10.4.7?

Because he can't connect to the internet to get the 10.4.8 update!

---------- Post added at 13:04 ---------- Previous post was at 12:59 ----------

Quote:

Originally Posted by stripes

Monkey, no firewall, unless the Mac has something built-in, and I don't think it has.

Mac OS X does have a built in Firewall.
Go into system preferences, and then Sharing, then click on the 'Firewall' tab.
It will either say 'Firewall On' or 'Firewall Off'.
If it is on, turn it off, just click the 'Stop' button.

Ian

Dark Fiber · 23-02-2007, 12:11

Quote:

Originally Posted by parky

Because he can't connect to the internet to get the 10.4.8 update!

---------- Post added at 13:04 ---------- Previous post was at 12:59 ----------

Mac OS X does have a built in Firewall.
Go into system preferences, and then Sharing, then click on the 'Firewall' tab.
It will either say 'Firewall On' or 'Firewall Off'.
If it is on, turn it off, just click the 'Stop' button.

Ian

Let me rephrase that. Did you get the machine through normal retail channels?

As I pointed out earlier:
1) the OS X firewall is off by default (and I haven't heard of it interfering with DHCP requests which of course it shouldn't

)

2) I am worried about this workaround not surviving a restart.

stripes · 23-02-2007, 12:44

So, in order.

Mark: tried that, precisely as instructed. Data on final ifconfig comes back as before, i.e. reading the G3 address in the 'ether' line. But how do we hold it there? Just doing another restart as I type, so.... no again, on restart, ifconfig, data changes so that the ether line reads a different set of figs.

Dark: bought it from Apple themselves, two weeks back. Well, that was the first iMac. After a week I convinced them it was faulty and I am now on my SECOND brand new iMac, still from Apple. Couldn't be MORE legal than that.
10.4.7 cos it came with the machine. As Parky points out, if I was connected to the internet on the OSX iMac I might download the upgrade!

Dark again: PEDANTIC I like, in these situations. It's necessary.
I went to Network Pane, Configure ipv4, chose Using DHCP with manual address, put in the address, Apply Now; went back to Configure ipv4, chose Using DHCP instead, hit Apply Now. No go.

Firewall is OFF.

When/if the Router turns up, I will try it first with no cloning, just whatever basic set-up procedure it says. If no go, then I'll try the clone option (if I understood it properly it would help, but I'm beginning to grasp the concept).

Guys, I've got to disappear for an hour or two (went blind in one eye the other week, so a tedious hospital visit today [that's what I meant by my luck]) so will have to go quiet for a bit.

There's someone here in case the router turns up!

(What I really, really want is a Father or maybe a Son, who would come round here, sit me in the corner to play, while he pressed a few buttons and fixed the problem, then take me by the hand and sat me down at my computer. Still, you lot couldn't be trying harder, and I do appreciate it).

Allen.

NTLVictim · 23-02-2007, 12:53

Stripes, just found this VIDEO..

scroll down the page to the video window and click play..the resolution is rough, but the narrator explains it well. He's using a lynksys in the demo, but the principle is the same.

Sam

Dark Fiber · 23-02-2007, 12:53

Quote:

Originally Posted by stripes

Dark: bought it from Apple themselves, two weeks back. Well, that was the first iMac. After a week I convinced them it was faulty and I am now on my SECOND brand new iMac, still from Apple. Couldn't be MORE legal than that.
10.4.7 cos it came with the machine. As Parky points out, if I was connected to the internet on the OSX iMac I might download the upgrade!

Wasn't suggesting illegality, just PC World which is worse

It's just that Apple's supply chain is now very short ("just in time") and I thought 10.4.8 had been going out with new machines from Nov 2006.

melevittfl · 23-02-2007, 13:40

Quote:

Originally Posted by stripes

Mark: tried that, precisely as instructed. Data on final ifconfig comes back as before, i.e. reading the G3 address in the 'ether' line. But how do we hold it there? Just doing another restart as I type, so.... no again, on restart, ifconfig, data changes so that the ether line reads a different set of figs.

Dark again: PEDANTIC I like, in these situations. It's necessary.
I went to Network Pane, Configure ipv4, chose Using DHCP with manual address, put in the address, Apply Now; went back to Configure ipv4, chose Using DHCP instead, hit Apply Now. No go.

Stripes,

OK, almost there I think. Can you try doing what I've suggested above again and then, without restarting, do what Dark suggested.

As NTLVictim says, the solution won't stick when you restart, but if cloning the ethernet ID works, then you can go back to NTL as it would indicate a definite problem on their end.

Hope everything goes OK at the hospital.

freakfunk · 23-02-2007, 20:43

Do What I Dont - Probaly Been Said Before But I Aint Reading All The Posts- Buy A Router! The Best Way!

Dark Fiber · 24-02-2007, 03:09

Can I put my head above the parapet to put forward some insomniac speculations and a prediction to explain why I keep on about using the long-awaited router without cloning and why I have such reservations about using "sudo ifconfig" in the way suggested?

BTW Stripes, did you originally connect the G3 through the set-top box (STB) and later get given a stand-alone cable modem (SACM)?

All the original problems, with not one but two iMacs failing to pick up an IP address and reverting to the self-assigned 169. address and, more significantly, not being able to be jolted out of that state, would be consistent with the cable system treating your SACM as though it was (the modem part of) your STB. STBs are "provisioned" to work only with a single client MAC while the system allows SACMs to work with a change of client machines. The prediction is that the Belkin router will not connect with its "native" out-of-the-box MAC setting but will connect when you "clone" the G3's MAC number into it.

Now some thoughts about why MAC "spoofing" with a directly-connected machine might not be exactly equivalent to MAC "cloning" with a gateway router: bear in mind that I am not an IT professional and what little I knew about networking has already been increased by learning that OS X now allows spoofing!

The MAC number is intended to be unique to each Media Access Controller and unalterable as it is "burnt in silicon". "Spoofing" is, after all, usually done for nefarious purposes. The cable system interrogates the Media Access Controller of whatever equipment is directly connected to the SACM and gets back "packets" that contain, among other things, the MAC number of the Media Access Controller. Now, although a connected computer's operating system can be "hacked" to cause IP packets originated by the machine to contain a "soft" MAC number instead of the Media Access Controller's "hard" MAC number, it doesn't necessarily follow that its Media Access Controller will respond to incoming interrogations with packets containing the "soft" MAC number (because Media Access Controllers are designed to be largely autonomous so as to "take the load off the CPU". This is why ethernet connections are vastly superior to USB connections in the context of networking.)
A home gateway router is, however, rather different. Its Media Access Controller is specifically designed to be "programmable" to take account of those ISPs who try to restrict access to a single computer by reference to its MAC number. If cloned with a client machine MAC number, a home gateway router _must_ respond to interrogation with packets containing the new MAC number and indeed use that MAC number under all circumstances.

To sum up- on Stripes behalf, I was reading Ted Landau's monumental tome "Mac OS X Helpdesk" yesterday (!) and he goes so far as to state that "99% of problems when connecting Macs to broadband are the fault of the ISP" and I'm sure that is the case here. However, I don't see how to get VM/ntl to acknowledge that it is their problem and so the use of a router, although regrettable, will have to be the "fall back" solution to the problem. Stripes may find it useful to be able to connect more than one machine from time to time and some people are happier leaving a router on 24/7 and being able to turn off their computer. Personally, I just let my Macs go to sleep- and I will now try to do the same