VPN problem...

[Ben Scott]

On Thu, Oct 1, 2009 at 7:48 PM, Lloyd Kvam <python at venix.com> wrote:
> I've seen DSL modems with 2 modes of behavior:
>      * bridge mode ...
>      * NAT/router ...
>
> I don't know if the cable modems offer similar capabilities.

  It's a bit different in cable-modem-land.  DSL is typically running
some kind of PPP feed, so in bridge mode, you need to run your own
PPPoE service.  Cable is presented more like a regular Ethernet
broadcast medium.

  Most cable modems I've seen act like bridges: You're on one big
subnet with all your neighbors.  You can see their broadcast traffic.
You request a DHCP lease, just like you do on a corporate LAN, and get
it from a cable company DHCP server somewhere.  This is what I've seen
Comcast provide in every residential install.

  I have seen cable modems with integrated routers.  Conceptually,
these are the same as other SOHO routers, except the "Internet" port
is a coaxial F connector instead of an Ethernet jack.  They typically
combine a NAT router, firewall, WAP, Ethernet switch, coffee maker,
etc., just like the more general SOHO gateways do.

  When we subscribed to Comcast's "business service" with a static IP
address, they gave us something like the later.  It appears to be a
halfheartedly[1] re-badged SMC8014.  Built-in four port Ethernet
switch.  It was configured to do NAT, and assigned IP addresses via
DHCP in the 10.1.10.0/24 subnet.  But the static IP address is also
configured on the Ethernet switch.  In other words, the LAN side of
the integrated router has multiple IP addresses.

  You can manage the LAN side by going to <http://10.1.10.1/>.
Default username is "cusadmin"; default password is "highspeed".  I
recommend changing the password.  :)

[1] The front panel says "Comcast", but the top of the case still has
a giant "SMC" molded into the plastic.

-- Ben