Self-assigned IP address? Cable modem issue

[Morgenster]

Hi,

Does anyone know what to make of the following?
I have a slotloading Imac (orange) that was connecting to the internet through cable perfectly until yesterday. The cable modem is hooked up to an ethernet hub servicing my housemates and me. We share. My mac is connected to the hub.
When I look at my system preferences in the ethernet TCP/IP panel, I see that I have a self-assigned IP-address (starting with 169....) instead of the normal address which starts with 10. The ISP works with a DHCP system to assign those addresses. When I detach the ethernet cable the panel goes blank, and when I reattach I get the self-assigned IP again. "renew DHCP lease" doesn't help either. I don't see any other computers on the network, but I can log in to my own Imac via SMB/CIFS, which is kind of weird.
I tried switching all the ethernet cables in the hub this afternoon, and it still doesn't work.
My housemates have internet access BTW, but I don't.
So is this a problem with the hub, the modem or my mac?
I'm lost here.
Thx in advance for any advice.

Mark

 

[Morgenster]

Oops, just saw this is the wrong thread.
Sorry.
Can someone move me?

 

[Westside guy]

Okay, is it really a "hub" or do you mean a router? That is, are you getting your IP address from the "hub" (which would mean it's a router doing NAT), or are you all getting IP addresses from your cable company?

Edit: Oops. I just reread your post - you're doing NAT obviously because you mention a "10" address. Sorry about that. But it is confusing when a person says "hub" if they're talking about a router.

 

[tomf87]

Yeah, and if you are getting them from the cable company, it is possible they stopped issuing multiple IP's for each customer. In that case, get a router and then you can all share again.

 

[Morgenster]

Okay, is it really a "hub" or do you mean a router? That is, are you getting your IP address from the "hub" (which would mean it's a router doing NAT), or are you all getting IP addresses from your cable company?

Edit: Oops. I just reread your post - you're doing NAT obviously because you mention a "10" address. Sorry about that. But it is confusing when a person says "hub" if they're talking about a router.

Believe me, I'm even more confused.
The ethernet network is shared, and the ISP gives a maximum number of 8 IP addresses for the modem. It would be very strange if the number of IP's was maxed out, because someone would have to have like three computers running on the internet at the same time.
So are you saying the problem is with my service provider?

 

[SpaceMagic]

Try this application, it might help you in the future and where the problem is now: Welian NetDiagX - others have found it useful with routers etc.

 

[tomf87]

..Edit: Oops. I just reread your post - you're doing NAT obviously because you mention a "10" address. Sorry about that. But it is confusing when a person says "hub" if they're talking about a router.

Not necessarily. My DSL provider runs 10. addresses from them to the DSL lines. They then NAT to a public IP. Kinda interesting how it works.

Back on the issue, if the cable company is providing you 8 addresses, then you would need 8 computers to use up all of the IP addresses, not 3.

 

[Westside guy]

So are you saying the problem is with my service provider?

Not necessarily. You said you've switched cables - have you tried plugging into a different port on the hub?

Additionally, when you say you can log into your own iMac, do you mean you can do it from one of the other computers at your place? Or are you just connecting to "localhost"?

(Also might be worth mentioning what version of the OS you're running)

It is always possible your service provider made some change that's affected only your Mac. I remember one time when I was travelling - I'd arranged for a short-term internet account at the location. At the time I was using Red Hat Linux on my old laptop. I ended up having a dickens of a time connecting to them, because they were using an MS server that was doing some sort of MS-specific CHAP authentication.

Edit: Fixed spelling of "necessarily" after re-reading the post immediately above mine.

 

[Morgenster]

Found it! Or at least I think I did.
I disconnected the modem and the hub, and then waited some minutes before reconnecting. That seems to have done the trick.
Odd, if you ask me.
The ISP works for our university, and we have internet access through their modems. As a student I have to log in every day to get access, and recently they changed it so that if you switch off your computer you loose your connection and have to log in again. Maybe this change caused the problem.
I'm keeping an eye on this connection to see if it does anything weird again next time.
Well, thanks for the advice!
Greets,

Mark