Re: IFF_POINTOPOINT and netmasks

Richard B. Johnson (root@analogic.com)
Sat, 24 May 1997 22:05:51 -0400 (EDT)

On 24 May 1997, Miquel van Smoorenburg wrote:
>
> The thing is - the default netmask should be 255.255.255.255, but if want
> to override it, I think it should be possible. Right? At this moment the
> kernel prevents me from doing it by resetting things I explicitly set.
> Maybe Alexey Kuznetsov reads this, he should know..
>
> Mike.

But... The default route is where everything that is masked by your
network netmask should go! As such, a netmask on the default route
doesn't make any sense. Isn't it just a place-holder so that the tools
used to set the default route don't have to be special?

If you want to block a set of addresses from being accessed, you need
to use a router like the 'Cisco' or Linux "firewall". Lets say I don't want
anybody to access 123.321.321.321, I can't do this with a netmask without
preventing access to 254 other nodes (0xff - 1). You would have to "mask"
specific addresses. This is what routers can do for you.

Cheers,
Dick Johnson
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Richard B. Johnson
Project Engineer
Analogic Corporation
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