Date: Mon, 30 Apr 2007 12:59:13 +0100 From: Vince <jhary@unsane.co.uk> To: "Abraham K. Mathen" <akmathen@hotmail.com> Cc: freebsd-net@freebsd.org Subject: Re: Why can't I sendto() to 127.255.255.255 Message-ID: <4635DA11.7080401@unsane.co.uk> In-Reply-To: <BAY121-F177CD9A9B001734EFB8DB3DE4C0@phx.gbl> References: <BAY121-F177CD9A9B001734EFB8DB3DE4C0@phx.gbl>
next in thread | previous in thread | raw e-mail | index | archive | help
Abraham K. Mathen wrote:
> NOTE : A copy of this message was sent to freebsd-hackers also.
> Apologies for the separate mails.
>
> Hello freebsd-net,
> I wrote a short program (on FreeBSD 6.0), that attempts
> to call sendto() on a UDP socket, with 127.255.255.255 as
> the destination address. It failed - with errno 49 (EADDRNOTAVAIL).
> Setting SO_BROADCAST and IP_ONESBCAST did not help.
>
> After examining
> - various RFC's,
> - source code under /usr/src/sys/netinet/ and
> - archives of freebsd-hackers & freebsd-net,
> I have not been able to determine the reason.
>
> Is it possible to successfully sendto() on a UDP socket
> with 127.255.255.255 as the destination address? If yes,
> how can that be done.
>
> Specific questions :
> ----------------------------------------------------------
> - Is it correct to understand that 127.255.255.255 is the
> directed network broadcast address for net 127? If yes,
> which RFC specifies that?
>
> - If not, is 127.255.255.255 considered to be a host
> address? If yes, which RFC specifies that?
> ----------------------------------------------------------
>
As far as I am aware the only RFC's that define the 127.0.0.0/8 block
are rfc3330 which states,
127.0.0.0/8 - This block is assigned for use as the Internet host
loopback address. A datagram sent by a higher level protocol to an
address anywhere within this block should loop back inside the host.
This is ordinarily implemented using only 127.0.0.1/32 for loopback,
but no addresses within this block should ever appear on any network
anywhere
and rfc1122 which says:
{ 127, <any> }
Internal host loopback address. Addresses of this form
MUST NOT appear outside a host.
I would interpret this as 127.0.0.0/8 are all loopback host addresses,
but I'd be happy to be corrected.
Vince
> Could you please help me understand this?
>
>
> sincerely
>
> Mathen
> (Abraham K. Mathen)
>
> _________________________________________________________________
> Mega Airfare Sale. Click here Now.
> http://ss1.richmedia.in/recurl.asp?pid=18
>
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4635DA11.7080401>