[ale] 10.1.10.1 Comcast access from local LAN? (Slightly OT BUT there is Ubuntu AND PI involved!)

[Boris Borisov]

You should be able to access 10.10.10.x from 192.168.x.x.  you need static
route for that. Tier 3 obviously wrong.

On Fri, Feb 5, 2021, 11:55 Boris Borisov <bugyatl at gmail.com> wrote:

> Didn't get the whole network diagram.
>
> But attach old raspi to the Cisco and wifi adapter to the raspi in AP
> mode. You can wifi to raspi.
>
> On Fri, Feb 5, 2021, 11:45 Neal Rhodes via Ale <ale at ale.org> wrote:
>
>>
>> Our church has a Business Comcast DPC3939 connected to Our little Cisco
>> RV 180 VPN.
>>
>> The Comcast has a local IP of 10.1.10.1, and the WAN Static Address of
>> 50.248.230.105.
>>
>> Our Cisco router has a WAN address of 50.248.230.106, and it supports a
>> 192.168.1.X network behind that, which is where everything on the LAN
>> lives.
>>
>> INTERNET==>Comcast DPC3939 <===>Our Cisco RV180VPN<====Our 192.168.1.X
>> LAN <==JackTrip Raspberry Pi Virtual Studio
>>                           50.248.230.105
>> 50.248.230.106                                                          <==
>> Everything else on the LAN
>>                            10.1.10.1
>>                                   |== Ubuntu JackTrip Audio Server
>>                                           10.1.10.91
>>                                           Port Forwarding 4464, UDP
>> 61002-62000
>>
>> We really need to do a couple of things:
>> - our office administrators need to occasionally be able to http access
>> the Comcast router from our 192.168.1.X LAN.  They cannot.  Any attempt
>> times out.  (Fun fact: you CAN http to 50.248.230.105, and get a login
>> response, BUT the correct userid/password will result in a Password
>> failure.  It only allows login from the 10.1.10.1 address.)
>> - we need for ME to be able to occassionally get an ssh session from an
>> office PC TO the Ubuntu server.   Similar challenge I think.
>> - The Raspberry Pi Virtual Studio box in the sanctuary needs to connect
>> to the Ubuntu server on port 4464.   I think it can hit the external
>> address of the Comcast router for that.   I've got that port forwarding all
>> working now at home with a UVerse router.
>>
>> We can access the Comcast Router as http://10.1.10.1 IF we go downstairs
>> to the furnace room and plug into the LAN ports on the DPC3939.  The PC
>> will then get a 10.1.10.X address.
>>
>> Now, when I look at the DPC3939, I see no evidence that it has a static
>> route for our LAN.  So, when someone on, say 192.168.1.145 puts
>> 10.1.10.1 in their browser, the PC hands it to our Cisco router, it knows
>> it's not on our LAN, so it hands it to its gateway: the DPC3939.
>>
>> And then I THINK the DPC3939 then says, "I don't know where to send
>> 192.168.1.145" and so it times out.
>>
>> I THINK the Comcast router needs a static route that says 192.168.1.X is
>> behind our Cisco router: 50.248.230.106.
>>
>> Am I thinking right?  I don't mind stuffing in the route myself, but I
>> asked Comcast first, since it's their equipment.   Tier 1 said, "no that's
>> not possible".  Tier 3 response was:
>>
>> *1- you need to know, in order for two local networks to communicate they
>> have to be in the same lan scheme, either both 192.168.x.x or 10.1.x.x*
>>
>> *2-  My suggestion is to change the local IP scheme for Comcast
>> modem/router to match the other router *
>> *192.168.1.X*
>>
>> *3- Make sure the IP scope of the modem is not conflicting with the other
>> router.*
>>
>> *For example if the other router IP scope is from 192.168.1.1
>> to 192.168.1.100 then make the modem DHCP  192.168.1.101 to 192.168.1.200.
>> Same lan scheme different IP scope to avoid future issues.*
>>
>> The Tier 3 response sounds insane to me; if I'm on 192.168.1.145, and I
>> want to send data to 192.168.1.4, my IP stack will just put it out on the
>> LAN wire.   The Comcast router is never going to see that,  'cause it's
>> connected to the WAN port on our router.    The only way my gateway would
>> get involved is when a workstation knows that the destination is NOT on the
>> local network, and hence the packet needs to get passed to the gateway.
>> The Tier 3 response also seems to open up all kinds of security issues if
>> it in fact worked; then a compromise to anything on the Comcast side could
>> easily bleed into our LAN.
>>
>> What is kinda weird to me is that at home this "just works".  I have an
>> AT&T Uverse router which provides 192.168.1.X.  I have a Sonicwall VPN
>> router plugged into that, which provides a LAN of 192.168.100.X.   The
>> linux and PC devices are on the 100.X network.   There are a few expendable
>> devices and IOT on the 1.1 network.    I can ssh and http from the 100.1
>> network to hosts on the 1.1 network; but of course they cannot go the other
>> way.    I didn't do anything for this to happen.    Did the routers
>> exchange BGP and just figure that out?
>>
>>
>> Regards,
>>
>> Neal Rhodes
>>
>>
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