Help with Motorola SB5120

Help with Motorola SB5120
NewsGroups | Search | Tools
User Password
Register Now! Lost Password?
 comp.dcom.modems.cable  Post an article  get this group's latest topics as an RSS feed add this group's latest topics to your My MSN content add this group's latest topics to your My Yahoo content  add this group's latest topics to your Google content  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
Help with Motorola SB5120 Hose A. Cuervo 01-16-2006
Posted by Hose A. Cuervo on January 18, 2006, 10:02 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
$Bill wrote:
>
> The ISP controls the modem. Add a router between the modem and
> the PC and do your config there. Netgear/Linksys routers are
> cheap (at least here in the US - $30-40 on sale after rebate)
> and they give you added security to protect your PC. Get a
> wireless G router if you need wireless - else just get a wired
> one for maybe $10 less. Either should have a 4-port switch to
> connect your wired computers.
>

Right. When the modem is reset, my ISP uploads a config to the
tftp server running on the cable modem. I agree that my ISP has
the right to control equipment connected to it's network, including
blocking certain netbios garbage.

But does my ISP have the right to configure things on my LAN ?
What if someone in the same office here decides to connect to
the web interface on 192.168.100.1 and keep resetting the damn
thing ? Don't I have the right to configure a password on MY side
of the network ? And don't I have the right to change the LAN IP
from the default of 192.168.100.1 to suit the IP numbering on my
LAN as I see fit? This would have nothing at all to do with my ISP,
and they shouldn't even care. If I can monitor the cable modem
to graph the traffic statitistics using SNMP, shouldn't I be able to
set the read community string to something other than the default
of "public" ?

NMFall 20%
Posted by Warren on January 18, 2006, 11:27 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
Hose A. Cuervo wrote:
> But does my ISP have the right to configure things on my LAN ?

No. And they don't.

> What if someone in the same office here decides to connect to
> the web interface on 192.168.100.1 and keep resetting the damn
> thing ?

In the same office? This isn't a residential account?

If they work in the same office as you, and are on the same LAN that you're
on, then talk to your network admin or your boss about what they're doing.

If I misunderstand what you mean by "the same office", and you meant someone
else on the same node as you on the cable company's HFC network, then it's
not going to happen that way. Someone else looking for 192.168.100.1 won't
see your modem's interface. They'll see their modem's interface.


> Don't I have the right to configure a password on MY side
> of the network ? And don't I have the right to change the LAN IP
> from the default of 192.168.100.1 to suit the IP numbering on my
> LAN as I see fit?

You can do whatever you want on your side of the network, but I haven't seen
any cablemodems that allow you to change the IP address of their web
interface. But if you place a router between your LAN and the cablenetwork,
that's a moot point.

> This would have nothing at all to do with my ISP,
> and they shouldn't even care. If I can monitor the cable modem
> to graph the traffic statitistics using SNMP, shouldn't I be able to
> set the read community string to something other than the default
> of "public" ?

No. The cablemodem is not on your network. It is on the cable company's
network. If you haven't placed a router between it and your computers, then
you've placed all your computers on their network. A router would delineate
where your network ends, and their network begins. Everything on one side of
the router would be on your network. Everything on the other side of it
would be on the cable company's network. You only get to do things on the
cable company's network that they decide to allow you to do, and controlling
the modem's configuration isn't one of them.

You get to stay on your side, and do whatever you want to your LAN. They get
to stay on their side and do whatever they want to their WAN. The modem is
part of their WAN.

--
Warren H.

==========
Disclaimer: My views reflect those of myself, and not my
employer, my friends, nor (as she often tells me) my wife.
Any resemblance to the views of anybody living or dead is
coincidental. No animals were hurt in the writing of this
response -- unless you count my dog who desperately wants
to go outside now.

Compare and buy TaxCut and TurboTax Software:
http://www.holzemville.com/taxes/




Posted by Hose A. Cuervo on January 19, 2006, 3:38 am
If you were  Registered and logged in, you could reply and use other advanced thread options
Warren wrote:
> Hose A. Cuervo wrote:
>
>>But does my ISP have the right to configure things on my LAN ?
>
>
> No. And they don't.
>
>
>>What if someone in the same office here decides to connect to
>>the web interface on 192.168.100.1 and keep resetting the damn
>>thing ?
>
>
> In the same office? This isn't a residential account?
>
> If they work in the same office as you, and are on the same LAN that you're
> on, then talk to your network admin or your boss about what they're doing.
>
> If I misunderstand what you mean by "the same office", and you meant someone
> else on the same node as you on the cable company's HFC network, then it's
> not going to happen that way. Someone else looking for 192.168.100.1 won't
> see your modem's interface. They'll see their modem's interface.
>
>
>
>>Don't I have the right to configure a password on MY side
>>of the network ? And don't I have the right to change the LAN IP
>>from the default of 192.168.100.1 to suit the IP numbering on my
>>LAN as I see fit?

I used to have a D-Link that would.

>
>
> You can do whatever you want on your side of the network, but I haven't seen
> any cablemodems that allow you to change the IP address of their web
> interface. But if you place a router between your LAN and the cablenetwork,
> that's a moot point.
>
>
>>This would have nothing at all to do with my ISP,
>>and they shouldn't even care. If I can monitor the cable modem
>>to graph the traffic statitistics using SNMP, shouldn't I be able to
>>set the read community string to something other than the default
>>of "public" ?
>
>
> No. The cablemodem is not on your network. It is on the cable company's
> network. If you haven't placed a router between it and your computers, then
> you've placed all your computers on their network. A router would delineate
> where your network ends, and their network begins. Everything on one side of
> the router would be on your network. Everything on the other side of it
> would be on the cable company's network. You only get to do things on the
> cable company's network that they decide to allow you to do, and controlling
> the modem's configuration isn't one of them.
>
> You get to stay on your side, and do whatever you want to your LAN. They get
> to stay on their side and do whatever they want to their WAN. The modem is
> part of their WAN.
>

According to Motorola's own pdf datasheet, the SB5120
"Supports up to 32 users (one via USB and 31 via Ethernet
or 32 users on Ethernet)"

Also, the web interface shows a screen under the "Configuration" link with
the following info:

" DHCP Server Enabled
The SURFboard cable modem can be used as a gateway to the Internet by a
maximum of 32 users on a Local Area Network (LAN). When the Cable Modem
is disconnected from the Internet, users on the LAN can be dynamically
assigned IP Addresses by the Cable Modem DHCP Server. These addresses
are assigned from an address pool which begins with 192.168.100.11 and
ends with 192.168.100.42. Statically assigned IP addresses for other
devices on the LAN should be chosen from outside of this range"

Well, 42 minus 11 equals the 31 IP addresses they're talking about
in the pdf datasheet. "can be used as a gateway to the Internet"
"gateway" is a router, specifically a NAT router. So what
I'm trying to do is whatever I want on the LAN side. I get to stay on
my side, and they get to do whatever they want to their WAN.

By the "same office", I was actually simplifying and stretching the truth
a little bit. It _is_ a residential account, but will soon be part of a
VPN.
My whole point is that I paid for this sucker, and I do not have
administrative
control over the part of it that is connected to my side of the network.
Whether I actually set a password on the web interface, or change the
SNMP read or write strings is beside the point. I _should_ have these
abilities whether I decide to use them or not.

Posted by Mike Rush on January 19, 2006, 1:12 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
>
> According to Motorola's own pdf datasheet, the SB5120
> "Supports up to 32 users (one via USB and 31 via Ethernet
> or 32 users on Ethernet)"
>
>

Most cable modems support more than one user, but that requires more than
one IP address from your cable provider. Cable modems are usually
provisioned for only 1 IP address. The provider will probably charge
additional fees to give you more IP addresses. Most people put a router
(they're pretty cheap) between their LAN and the cable modem, giving them
complete control without paying for extra IP addresses from the provider.



Posted by Hose A. Cuervo on January 19, 2006, 7:31 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
Mike Rush wrote:
>
>>According to Motorola's own pdf datasheet, the SB5120
>>"Supports up to 32 users (one via USB and 31 via Ethernet
>>or 32 users on Ethernet)"
>>
>>
>
>
> Most cable modems support more than one user, but that requires more than
> one IP address from your cable provider. Cable modems are usually
> provisioned for only 1 IP address. The provider will probably charge
> additional fees to give you more IP addresses. Most people put a router
> (they're pretty cheap) between their LAN and the cable modem, giving them
> complete control without paying for extra IP addresses from the provider.
>
>

This post was helpful, thanks. It explains why when I connect up two
workstations through a switch or hub to the cable modem, I receive two
dhcp assigned publicly routable IPs from my ISP. The grade of
service I'm paying for allows me a max of 3.

But I am still confused about the statement I posted previously which
shows up in the cable modem's web interface, stating that up to 32
dhcp addresses can be assigned, within the IP block of 192.168.100.*

I have verified that this is true. When I disconnect the cable, or kick the
modem into standby, I can fire up 3 or 4 boxes and each one gets a dhcp
assigned address in the 192.168.100.* range. But what use are these
IPs, if they cannot be routed out and NAT translated once the cable is
reconnected to the WAN ?

Lets say I hook up a router with between my LAN and the modem.
The dhcp server on the cable modem seems pointless if the only way to
get it working on the lan is to disconnect the WAN side temporarily. I
could
configure the router to NAT the assigned addresses out, and then connect
up the cable again. What a mess. Better to run a dhcp server on
the router and use it to NAT everything out.

I'm sure that somewhere buried in encrypted archives somewhere at
Motorola, there is complete documentation on how to tweak every
feature of the SB5120. But lets face it, they don't want the average
end user messing with it. Unfortunate for those of us who wish to
learn and experiment. Not everybody wants to hack, do damage,
or violate the terms of acceptable use just for the thrill of it.

Thanks to everybody for your input, and best wishes :)
I'm out of here for awhile......










Similar ThreadsPosted
Motorola SB5120 / Optimum Online Problem - Need help. December 12, 2005, 5:56 pm
sb5120 vs sb5100 April 5, 2005, 3:02 pm
what's next after Motorola's SB5120? February 23, 2006, 10:47 pm
SURFboard SB5120 June 1, 2007, 7:54 pm
SB5120 & Comcast Woes December 18, 2006, 3:51 pm
Motorola SB5100 March 14, 2005, 9:25 am
Problems with ssh, sftp on Motorola SBG 900 February 28, 2005, 10:37 am
IPsec passthru on Motorola SBG 900 July 19, 2005, 6:39 pm
New Firewire for Motorola Modems September 17, 2005, 4:08 am
Anyone using a Motorola VT2442 router? July 20, 2006, 1:20 pm

other useful resources:
The Federal Communications Commission (FCC)
Telecommunications Industry Association
Electronic and Software Security Products and Services
International Telecommunication Union

Custom CGI Perl and PHP programming by 1-Script.com

Contact Us | Privacy Policy
The site map in XML format XML site map