[X-Unix] How to determine which network component is failing

[Alexandre Gauthier]

Just two quick insights, while you guys are busy writing really delicious
shell scripts, they or may not be useful at all.

1) My experience with Motorola cable modems is, well, displeasing to say the
least. These modems are known to remember the last MAC address that was
connected to them. Either that, or it's the ISP's DHCP server that does
this. I assume it's the modem since the new Scientific Atlanta modems
Videotron Cable distributes over here don't have this problem. Basically, a
reboot of the modem is in order for DHCP to work whenever the Mac address
changes, and in some other situations. This is probably not useful, but it
is good to know when you're trying to get a DHCP lease and it's failing
miserably, and you're spending too much time in obscure network settings.

2) If you are to use an "opened" firmware with your router (I have been
building my own firmware images for various needs, including a municipal
wireless project in my local town), you should know that the SSH server that
is normally used is DropBear SSH, since OpenSSH would waste many precious
megabytes of Flash memory. I had only limited success in adding public keys
to DropBear. In fact, I think it downright doesn't support that. You can use
keys to auth FROM the dropbear client, that will work. But the keys have to
be in dropbear format, and depending on your distribution on the router (I
think sveasoft does it that way, don't remember), the keys are stored in
NVRAM. (this can be access by using the nvram(1) command).

If you get OpenSSH on the router, you could use a passwordless key, but only
allow it to run one particular command. That would work too. You just have
to add the following line to authorized_keys.



On 26/07/06 05:43, "Charles Howse" <chowse at charter.net> wrote:

> 
> On Jul 25, 2006, at 10:45 PM, Stroller wrote:
> 
>> Well done!
>> 
>> I shall be keeping a copy of these notes in my archive. I shall
>> have to install curl on a customer's Windows PC and give her an
>> icon to click which will reboot the router for her.
>> 
>> 
>> On 25 Jul 2006, at 23:25, Charles Howse wrote:
>>>> ...
>>>> I think the relevant sections of the HTML are...
>> 
>> Addendum:
>>    <form method=get action=Gozila.cgi>
>> 
>>>> <SCRIPT language=JavaScript>function pppoeAction(F,I)
>>>> { F.pppoeAct.value = I; F.submit();}function DHCPAct(F,I)
>>>> { F.dhcpAction.value = I; F.submit();}function showAlert(){alert
>>>> ('');}</SCRIPT>
>>>> 
>>>> and:
>>>> 
>>>> <input type=hidden name=dhcpAction> ...
>>>> <input type=button value='DHCP Renew' onClick=DHCPAct(this.form,1)>
>>>> 
>>>> `curl --manual` gives more examples than `man curl`, but the
>>>> http://curl.haxx.se/ website looks more comprehensive still. They
>>>> have a mailing list, so you might find what you need by searching
>>>> the archives of that, or posting to it.
>>> 
>>> I made quite a bit of progress playing with curl this afternoon.
>>> FYI, the following commands work:
>>> 
>>> - Router -
>>> # dhcp release - $ curl -u admin:pw "http://192.168.254.254/
>>> Gozila.cgi?dhcpAction=0"
>>> # dhcp renew - $ curl -u admin:pw "http://192.168.254.254/
>>> Gozila.cgi?dhcpAction=1"
>> 
>> These curl commands relate to the HTML / Javascript snippet in the
>> quoted above it, I think...
>> 
>>> - Modem -
>>> # Reboot Modem - $ curl -d "BUTTON_INPUT=Restart%20Cable%20Modem"
>>> 192.168.100.1/configdata.html
>> 
>> Can you possibly post the HMTL from the webpage for the modem,
>> please, so I can see can example of when I might use this form?
>> 
> It's too big, over 5k limit.  Here is all you need.
> 
> <FORM METHOD="POST" ACTION="http:/configdata.html">
> <INPUT TYPE="submit" NAME="BUTTON_INPUT"
> value="Restart Cable Modem">
> 
> 
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> 
> 
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