RE: FN-FORUM: TCP/IP Properties

date posted 2nd February 2007 11:23

> > The 255.255.255.255 subnet mask is valid when specifying the
> > settings for a PPP adaptor, like an ISDN or ADSL modem.
> > Usually the Gateway address is identical to the IP Address,
> > though not in the settings you have presented. Enter the same
> > information into the Gateway field that you entered into the
> > IP Address field. The subnet mask is set to
> > 255.255.255.255 to prevent IP access to other equipment on
> > the network at the remote end of the connection. Give it a whirl, see
> > what happens. And Dai, sanity not confirmed just yet we'll wait to
> > hear back.

I've had a reply from 1&1 support about the strange settings:

"The subnet mask is correct. In order for servers within our network
to communicate with each other they need to have that subnet mask."

Andrew do you mean these are normal settings for ADSL? I've checked my ADSL
setup here and on the ADSL port I have a subnet mask of 255.255.255.255.
That does make sense.

The machine in question is a webserver - part of a much large network. It's
a really odd way of setting up a machine like this. I've never seen it
before.

The problem with the subnet mask is that the only IP my server can ever talk

to is its own (212.227.21.59). The gateway is used to talk to any hosts
that aren't on the same network. Since the gateway is not in the same
subnet it shouldn't be able to communicate with it!! I think 1&1 have
strange and complicated routing going on.