Urgent 4.9 networking problems

Matthew Seaman m.seaman at infracaninophile.co.uk
Thu Jun 24 14:49:36 PDT 2004


On Thu, Jun 24, 2004 at 02:31:58PM -0700, Kevin Stevens wrote:
> On Thu, 24 Jun 2004, Dave Raven wrote:
> 
> > # ifconfig fxp1
> > fxp1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> >         inet x.y.186.3 netmask 0xffffff00 broadcast x.y.186.255
> >         inet x.y.186.1 netmask 0xffffffff broadcast x.y.186.1
> >         inet x.y.186.15 netmask 0xffffffff broadcast x.y.186.15
> >         inet x.y.186.14 netmask 0xffffffff broadcast x.y.186.14
> >         inet x.y.186.142 netmask 0xffffffff broadcast x.y.186.142
> >         inet x.y.186.33 netmask 0xffffffff broadcast x.y.186.33
> >         inet x.y.186.124 netmask 0xffffffff broadcast x.y.186.124
> >         inet x.y.186.250 netmask 0xffffffff broadcast x.y.186.250
> >         inet x.y.186.122 netmask 0xffffffff broadcast x.y.186.122
> >         inet x.y.186.25 netmask 0xffffffff broadcast x.y.186.25
> >         inet x.y.186.127 netmask 0xffffffff broadcast x.y.186.127
> 
> I don't disagree with the other posters that mentioned DNS timeouts, but
> in addition those broadcast addresses aren't right.  Since all the
> addresses are within the same /24 subnet, they should all be .255 (which
> is the default, so you wouldn't need to specify them.

Err -- no.  The broadcast address is a function of the netmask.
Specifically, looking at IPv4 addresses/masks as 32bit integers, the
broadcast address has all ones where ever the netmask has zeros.  The
OP actually has it right.  Especially as that is clearly the slightly
edited output from ifconfig(8), and ifconfig automatically calculates
the broadcast address from the inet address and netmask.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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