Default OM settings, no lan messed up

[Joel Newkirk]

On Mon, 13 Oct 2008 11:04:34 -0700, Rodney Myers <rdmyers at mtpalomar.net>
wrote:
> On Oct 13, 2008, at 10:36 AM, Joel Newkirk wrote:
> 
>> On Mon, 13 Oct 2008 10:10:28 -0700, Rodney Myers <rdmyers at mtpalomar.net
>> >
>> wrote:
>>> OS = OS X 10.5.5

>>> I was able to SSH into the OM. Once I did that, I edited & changed
>>> the /etc/network/interfaces file to reflect "my" lan.
>>>
>>> 192.168.1.***
>>>
>>> Before I logged out, I catted the file to make sure that I had
>>> correctly set that file. It all looked correct
>>>
>>> I then logged out of the phone & restarted the phone, thinking I now
>>> would be able to ssh, without jumping through hoops.
>>>
>>> No such luck.
>>>
>>> Now, the IP address is neither the default nor anything on the
>>> 192.168.1.*** network..
>>>
>>> Any help in getting the phone functioning again, would be greatly
>>> appreciated.
>>>
>>> Many thanks
>>
>> What is the full IP, gateway, and subnet mask you set on the
>> FreeRunner,
>> and on the USB network interface on your host?  Does it overlap the
>> subnet
>> on any other interface on the host?
>>
>> j
>>
>> If you are able to set up a packet sniffer on USB network device on
>> the
>> host, try tapping 'installer' on the FR and see what IP the connection
>> attempt comes from.
> 
> I "thought" i had it setup this way
> 
> 	address 192.168.1.20
> 	netmask 255.255.255.0
> 	network 192.168.1.0
> 	broadcast 192.168.1.255
> 	gateway 192.168.1.101  (my MBP)
> 
> My home lan is using 192.168.1.*** range.

That's the problem there.  Your desktop system already has a valid working
route to 192.168.1.0/24 on ethernet.  When you set up another network
interface with the same subnet (192.168.1.0/24) then the result is
OS/kernel dependent, but almost NEVER pretty.

Try setting the usb networking on the host to 192.168.1.21, subnet mask
255.255.255.248 (that's /29).  You should be able to communicate with the
FR again at that point.  The FR will still not connect to the world though.
 At the minimum you'll need to change the gateway to 192.168.1.21, and deal
with /etc/resolv.conf.  Then you should be able to reach the internet from
the FR, though your LAN (except the host itself) will be unreachable.



The safest setup is to have different subnets (like 192.168.1.0/24 and
192.168.0.0/24) on each interface.  If you're currently running
192.168.1.0/24 on your LAN, then the usbnet connection should use a
different (non-overlapping) subnet for simplest and best functioning.  The
MBP will need to NAT connections from the FR - presuming it just passes
them, the rest of your network (including router/gateway to the internet)
will send responses to the IP of the FR, which it will have no idea how to
reach since it's 'behind' the MBP from the router's point of view.  To fix
that you'd have to make manual routing changes on the router, or set up
proxy arp on the MBP, or a few other possibilities - all far more complex
than just using different subnets.

The 'fix' I mentioned first works because routing decisions (IE, "what
interface do I use for a packet going to a.b.c.d?")  are typically made by
looking at the MOST RESTRICTIVE route first.  So if 192.168.1.20 is
technically within two subnets for the host (192.168.1.0/24 on eth0 and
192.168.1.16/29 on usb0, for example) then it will use the route with the
smaller subnet.  (which means the larger subnet mask number in /24 /29
format)  But normally other devices on the 192.168.1.0/24 network (like
another computer, or router, or network printer) will expect 192.168.1.20
to be RIGHT on the wire out their own interface, NOT on the other side of
your MBP.  (from their perspective the MBP is a router they need to use to
reach 192.168.1.21, and they don't know that)

The other possibility (which I have no idea how to implement on osX) is to
bridge the ethernet or wireless interface on the host to the usb networking
interface.


If for whatever reason you're insistent on keeping 192.168.1.0/24 addresses
on everything, you can set up the smaller /29 subnet I mentioned at the top
on both the host and the FR, and set up default route and nameserver on the
FR appropriately.  Note that without lower-level routing tweaks the FR will
NOT be able to communicate correctly with other IPs in 192.168.1.0/24, just
with and through the host.

> No idea on how to sniff packets, at this time.

I don't honestly know what's available for the Mac, but I'd be surprised if
wireshark were not.  That (or tshark, the text-only console variant) is
what I use almost exclusively on linux and windows systems.

Oh, and back to your original post for a moment, you'll need to go into
Installer and install Terminal, it's not preinstalled in the image.  (once
Installer can communicate with the internet again, that is;)

j


PS: ipcalc is a handy tool...  

$ ipcalc -b 192.168.1.20/29
Address:   192.168.1.20         
Netmask:   255.255.255.248 = 29 
Wildcard:  0.0.0.7              
=>
Network:   192.168.1.16/29      
HostMin:   192.168.1.17         
HostMax:   192.168.1.22         
Broadcast: 192.168.1.23         
Hosts/Net: 6                     Class C, Private Internet