2 wire DSL

Luke Militello luke at digitalenigma.net
Sun Dec 7 06:51:52 UTC 2008


Leonard Chatagnier wrote:
> --- On Sat, 12/6/08, Luke Militello <luke at digitalenigma.net> wrote:
> 
>> From: Luke Militello <luke at digitalenigma.net>
>> Subject: Re: 2 wire DSL
>> To: "Ubuntu user technical support, not for general discussions" <ubuntu-users at lists.ubuntu.com>
>> Date: Saturday, December 6, 2008, 11:38 PM
>> Leonard Chatagnier wrote:
>>> --- On Sat, 12/6/08, Luke Militello
>> <luke at digitalenigma.net> wrote:
>>>> From: Luke Militello
>> <luke at digitalenigma.net>
>>>> Subject: Re: 2 wire DSL
>>>> To: "Ubuntu user technical support, not for
>> general discussions"
>> <ubuntu-users at lists.ubuntu.com>
>>>> Date: Saturday, December 6, 2008, 11:18 PM
>>>> Leonard Chatagnier wrote:
>>>>> --- On Sat, 12/6/08, Luke Militello
>>>> <luke at digitalenigma.net> wrote:
>>>>> BIG SNIP
>>>>>> Sounds to me the problem is a double NAT. 
>> From
>>>> what I am
>>>>>> reading... is 
>>>>>> this how your network is setup?
>>>>>>
>>>>>> INET <----> 2WIRE-DSL <---->
>> WIFI-RTR
>>>>>> <----> END-USERS
>>>>>>
>>>>>> Most DSL routers do NAT by default,
>> however lack
>>>> the option
>>>>>> of WiFi 
>>>>>> capabilities so most users opt for a
>> secondary
>>>> router.  If
>>>>>> your network 
>>>>>> is like the one above, then your WiFi
>> router is
>>>>>> "NAT'ing" down to one IP 
>>>>>> address on the "DSL network". 
>> Although
>>>> double
>>>>>> NAT is bad for port 
>>>>>> forwarding and I wouldn't recommend
>> it, it can
>>>> be done,
>>>>>> however you must 
>>>>>> be sure the two private ranges are not
>>>> conflicting.  In
>>>>>> other words, if 
>>>>>> the device doing NAT sees the same network
>> on each
>>>> side, it
>>>>>> will get 
>>>>>> confused.  If this is the case, do
>> something like
>>>> this.
>>>>>> INET <----> 2WIRE-DSL
>>>> <--(192.168.1.0/24)-->
>>>>>> WIFI-RTR 
>>>>>> <--(192.168.2.0/24)--> END-USERS
>>>>>>
>>>>>> You will still have double NAT in place,
>> but this
>>>> should
>>>>>> allow 
>>>>>> connectivity to 192.168.1.254 (your DSL
>> box). 
>>>> Because this
>>>>>> IP address 
>>>>>> only exists on one side, your WiFi router
>> would
>>>> treat it
>>>>>> like a "public" 
>>>>>> IP and translate it just fine.  Feel free
>> to use
>>>> any of
>>>>>> these networks 
>>>>>> as they are all reserved for private use.
>>>>>>
>>>>>> 10.0.0.0/8 (10.0.0.0-10.255.255.255)
>>>>>> 172.16.0.0/12 (172.16.0.0-172.31.255.255)
>>>>>> 192.168.0.0/16
>> (192.168.0.0-192.168.255.255)
>>>>>> However, the best approach would be to
>> directly
>>>> connect one
>>>>>> PC to your 
>>>>>> DSL box (via DHCP), login and disable NAT,
>> connect
>>>> your
>>>>>> WiFi router back 
>>>>>> up, reboot both DSL and WiFi router (in
>> that
>>>> order), then
>>>>>> login to your 
>>>>>> WiFi router and verify for its public
>> address that
>>>> it does
>>>>>> NOT have an 
>>>>>> IP address which falls in the ranges given
>> above.
>>>>>> One more thing to mention, most DSL
>> routers will
>>>>>> automagically disable 
>>>>>> NAT once they see a connection to the
>>>> WAN/DSL/Internet
>>>>>> side.  In this 
>>>>>> case, your network should be fine.  Simply
>>>> disconnect the
>>>>>> DSL box from 
>>>>>> the phone line, reboot it and you should
>> get
>>>> connectivity
>>>>>> to 
>>>>>> 192.168.1.254 for management purposes. 
>> Once
>>>> plugged back
>>>>>> in to the 
>>>>>> phone line, connectivity to 192.168.1.254
>> will go
>>>> away. 
>>>>>> However, to do 
>>>>>> this, I would plug a PC directly into the
>> DSL box
>>>> to avoid
>>>>>> network 
>>>>>> confusion if you WiFi router uses the same
>> network
>>>> as your
>>>>>> DSL box (as 
>>>>>> stated above).
>>>>>>
>>>>>> Hope this helps, if not, please enlighten
>> me on
>>>> your
>>>>>> network setup as 
>>>>>> there are too many posts for me to trace
>> back on
>>>> ;)
>>>>>>
>>>>> Honestly, Luke, I have no idea what you mean
>> at the
>>>> beginning
>>>>> of your reply so let me try to explain.  Two
>> machine
>>>> LAN.  Outside
>>>>> world connected to 2wire DSL router/ modem
>> combo. 
>>>> Router wired
>>>>> to new Gateway Intrepid machine which is now
>> in shop
>>>> so I have no
>>>>> hard wired maching in place currently.  The
>> other
>>>> machine in anther
>>>>> room has a syslink wmp54g wifi card installed
>> and a
>>>> NIC also but
>>>>> not connected to anything.  The eth0 interface
>> is
>>>> setup with same
>>>>> IP as the wifi.
>>>>> I don't know about NAt either and If I
>> understand
>>>> what you said
>>>>> I don't have a separate router and modem. 
>> They
>>>> are all in one box,
>>>>> a 2wire 1701hg router/modem combo.  I've
>> only had
>>>> experience 
>>>>> with this one router.modem combo.  it seem
>> that you
>>>> refer to
>>>>> each separately above, but I'm not sure. 
>> In any
>>>> case, I'm about
>>>>> to move the wireless machine and hook it up
>> directly
>>>> to the
>>>>> router/modem(after unplugging it to reset) and
>> start
>>>> the machine
>>>>>  back up under DHCP to see if I can connect to
>>>> 192.168.1.254 and
>>>>> access the 2wire setup page again.  Hope this
>> explains
>>>> a liitle.  I
>>>>> know what you mean, I've been answering
>> replyies
>>>> on this issue all
>>>>> day and haven't had time to move the
>> machine or
>>>> switch back to DHCP
>>>>> yet but will do so now.   Thanks for you
>> input.  Sorry
>>>> I didn't uderstand
>>>>> most of it but I did say I was a network idiot
>> in an
>>>> earlier post.
>>>>> Leonard Chatagnier
>>>>> lenc5570 at sbcglobal.net
>>>>>
>>>>>
>>>>>
>>>> No, problem, that does clear some stuff up so
>> ignore the
>>>> bulk of my last 
>>>> reply.  So to clarify, you have (right now) one PC
>>>> connected via 
>>>> wireless to your 2Wire DSL.  You can connect to
>> the
>>>> Internet just fine, 
>>>> but cannot connect to the 2Wire?  Try this
>> command...
>>> That's correct.
>>>  
>>>> [luke at Ignignokt ~]$ netstat -nr
>>>> Kernel IP routing table
>>>> Destination     Gateway         Genmask        
>> Flags   MSS
>>>> Window  irtt 
>>>> Iface
>>>> 10.188.39.192   0.0.0.0         255.255.255.192 U 
>>        0
>>>> 0 
>>>>   0 eth0	<-- My local network.
>>>> 169.254.0.0     0.0.0.0         255.255.0.0     U 
>>        0
>>>> 0 
>>>>   0 eth0	<-- If you have this as well, ignore
>> it.
>>>> 0.0.0.0         10.188.39.193   0.0.0.0         UG
>>        0
>>>> 0 
>>>>   0 eth0	<-- My default gateway.
>>>>
>>>>
>>>> See where I have "10.188.39.193"?  That
>> is my
>>>> default gateway hence the 
>>>> "G" flag.  In your case, is yours
>> 192.168.1.254? 
>>>> If it is something 
>>>> different, that is most likely the IP address of
>> your
>>>> 2Wire.  Try 
>>>> connecting to whatever IP address is listed there
>> in
>>>> Firefox.
>>>>
>>> I have attached the output but it still says my
>> gateway
>>> is 192.168.1.254 which is what it's supposed to be
>>> the 2wire 1701hg router/modem.  Thanks for trying.
>>>
>>> lchata at ubuntu:~$ netstat -nr
>>> Kernel IP routing table
>>> Destination     Gateway         Genmask         Flags 
>>  MSS Window  irtt Iface
>>> 192.168.1.0     0.0.0.0         255.255.255.0   U     
>>    0 0          0 eth0
>>> 192.168.1.0     0.0.0.0         255.255.255.0   U     
>>    0 0          0 wlan0
>>> 169.254.0.0     0.0.0.0         255.255.0.0     U     
>>    0 0          0 wlan0
>>> 0.0.0.0         192.168.1.254   0.0.0.0         UG    
>>    0 0          0 wlan0
>>> 0.0.0.0         192.168.1.254   0.0.0.0         UG    
>>    0 0          0 eth0
>>> lchata at ubuntu:~$ 
>>>
>>> Leonard Chatagnier
>>> lenc5570 at sbcglobal.net
>>>
>>>
>> I see you have duplicate entries, one for eth0 and one for
>> wlan0.  Are 
>> both these interfaces currently up?
>>
> No, the NIC, eth0, is not connected to anything; it's just has
> has been setup with same static IP's as the wireless automatically
> I think,
>> Send the output of "ifconfig -a" please.  Also,
>> what is each interface 
>> using?  DHCP or are they static'ed, or one of each?
>> There both static. And I have just moved the computer to the
> router modem room and fixing to change to DHCP to check things out.
> Here is the output you requested:
> lchata at ubuntu:~$ ifconfig -a
> eth0      Link encap:Ethernet  HWaddr 00:50:04:99:48:F4
>           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
>           inet6 addr: fe80::250:4ff:fe99:48f4/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:151 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:3580 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:28703 (28.0 KB)  TX bytes:602097 (587.9 KB)
>           Interrupt:11 Base address:0x4000
> 
> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           RX packets:69 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:69 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:5282 (5.1 KB)  TX bytes:5282 (5.1 KB)
> 
> wlan0     Link encap:Ethernet  HWaddr 00:12:17:92:33:D8
>           inet addr:192.168.1.2  Bcast:192.168.1.255  Mask:255.255.255.0
>           inet6 addr: fe80::212:17ff:fe92:33d8/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:3779 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:202 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:2884815 (2.7 MB)  TX bytes:75527 (73.7 KB)
> 
> wmaster0  Link encap:UNSPEC  HWaddr 00-12-17-92-33-D8-00-00-00-00-00-00-00-00-00-00
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
> 
> lchata at ubuntu:~$
> 
> 
>> -- 
> 
> Leonard Chatagnier
> lenc5570 at sbcglobal.net
> 
> 
> 

I see both interfaces are up and using the same IP address.  Could be a 
duplicate route which is confusing the routing table.  Try this...

   sudo ifconfig eth0 down

Then do...

   ifconfig eth0

To confirm it is down, then do...

   netstat -nr

To confirm you only have one default route for 192.168.1.254 via wlan0. 
  And finally, try connecting to your 2wire.

-- 

Luke J Militello, CCNA
Network Engineer
Technical Operations
Charter Communications
Cisco Certified Network Associate
Michigan Technological University, BS
Computer Network & System Administration




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