Why do packets to 127.255.255.255 cause dial-up?

Paul Civati paul at xciv.org
Fri Mar 31 01:12:46 BST 2000


Nik Clayton <nik at freebsd.org> wrote:

> The more interesting question is why is this happening?  The only other
> IP enabled system I have to hand is Win98 (I know, I know), and a quick
> "route print" shows that the 127.0.0.1 route has a /8 netmask rather than
> a /32.

Good to see MS doing things differently as usual.

> It's my understanding that 127/8 is the 'local net', and that packets to

Agreed.

> any 127/8 address should go via the loopback interface.  That being the
> default, shouldn't a 127/8 route automatically exist to lo0?

You would think so, but judging by the below, there must be a 
reason?

> If it should, is it just my system that's misconfigured, and does 
> everybody else have a 127/8 route on their systems?

Nope:

% uname -sr
FreeBSD 2.2.7-RELEASE
% netstat -rn
[..]
Destination        Gateway            Flags     Refs     Use     Netif Expire
127.0.0.1          127.0.0.1          UH         10       42       lo0

% uname -sr
FreeBSD 3.4-RELEASE
% netstat -rn
[..]
Destination        Gateway            Flags     Refs     Use     Netif Expire
127.0.0.1          127.0.0.1          UH          0     1065      lo0

% uname -a
SunOS mustang.xciv.org 5.7 Generic_106541-08 sun4m sparc SUNW,SPARCstation-10
% netstat -rn
[..]
  Destination           Gateway           Flags  Ref   Use   Interface
-------------------- -------------------- ----- ----- ------ ---------
127.0.0.1            127.0.0.1             UH       0     40  lo0

-Paul-




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