Subject: Re: how do I configure PPP to do this?
To: Paul Goyette , Brad Salai <>
From: Ronald Khoo <>
List: current-users
Date: 10/24/1997 07:34:32
"Shyeah right, etc.." <> wrote:
> What's the number after the slash in those IP addresses, i.e.:
> ....

to which, Paul Goyette <> replied:
> A new fangled short-hand notation to describe the netmask.  /24 is the
> same as, /32 ==>

(and others said much the same thing).

which is correct, of course.  The one oddity is that a netmask of /32
has semantics that are provided be the IFF_POINTOPOINT interface flag
rather than the netmask field in the BSD (ie our :-) IP software.  In
other words, /32 is weird.

[ It's also weird because /30 and less is legal; /32 is meaningful,
  but different; but /30 is pretty much meaningless (because it's not
  pointopoint, so it has a broadcast address, a network address, and no
  host addresses :-) ]

Then Brad Salai <> said:

> but isn't that a kind of no-no? aren't you supposed to use
> specific blocks for unregistered addresses:
[ network deleted
> where the addresses are known to be private?

That is *also* a common configuration.  However, the original
question referred to a real routed network.  In fact, here's
a quote:

In Message-ID: <> to
current-users@NetBSD.ORG, "John F. Woods" <> wrote:

> I have what must be a fairly typical setup:  a PPP link to my ISP which has
> assigned me a static IP address; a local class C network (a real allocation,
> not one of the nonrouted networks) for my home Ethernet (doesn't EVERYONE
> have Ethernet in their homes?).

Of course we do.  And like you, I too have a real routed network at
home (although I have a /28 rather than a /24 like you).  People with
dedicated connections tend to use a mixture of routed and unrouted
networks depending upon security considerations, but people with
dialups tend to use unrouted networks behind a NAT device or proxy
because ISPs tend to either not support routing networks behind
dialups, or charge quite a lot more for doing so (I know we do).

Ronald Khoo <> Voice: +44 181 371 1000 Fax: +44 181 371 1150