alias netmask bug?

[Jeremy Chadwick]

On Tue, Jul 24, 2007 at 03:34:54AM +0300, Evren Yurtesen wrote:
>  I remember from earlier versions of FreeBSD that it had a restriction about 
>  alias IP netmasks (somewhere in 3.x,4.x days)...
> 
>  as explained here:
>  http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-virtual-hosts.html
> 
>  However I tried on the loopback interface to add a 2nd IP with the same 
>  netmask as the original IP and it accepts it fine. (on 6.2)
> 
>  lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
>          inet 127.0.0.1 netmask 0xff000000
>          inet 127.0.0.2 netmask 0xff000000
> 
>  Is FreeBSD allowing this a bug or ???

It's not a bug.  Why did you disregard the instructions, though?

>  If this is not a bug. What happens if an interface which is connecting to 
>  the machine has 2 IP addresses with same netmask which is not 
>  255.255.255.255? Does FreeBSD use each IP randomly?

Don't know, but my guess is no, it probably does not use "each IP
randomly", and I cannot even fathom the network breakage that would
ensue as a result of such.

-- 
| Jeremy Chadwick                                    jdc at parodius.com |
| Parodius Networking                           http://www.parodius.com/ |
| UNIX Systems Administrator                      Mountain View, CA, USA |
| Making life hard for others since 1977.                  PGP: 4BD6C0CB |