What's new on the 127.0.0/24 block in 7?

[Chris H.]

Quoting Jeremy Chadwick <koitsu at freebsd.org>:

> On Tue, Mar 04, 2008 at 02:48:31AM -0800, Chris H. wrote:
>> In long; Both servers have the same (and only) entry:
>> /etc/defaults/rc.conf: ifconfig_lo0="inet 127.0.0.1"
>> no more, no less.
>> The RELENG_6 server reports:
>> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
>>        inet 127.0.0.1 netmask 0xff000000        inet6 ::1 prefixlen 128
>>    inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
>> The 7-RC3 did not (I'd provide the output, but I've since added
>> and activated an entry in /etc/rc.conf that provides a /24 on
>> lo0). Since I'm only /really/ interested in SWIP'ing 3 IP's out of
>> the the block 254 will be more than enough.
>
> Okay so it sounds like there's two separate issues here:
>
> 1) The issue with rbldnsd not working for you on RELENG_7 (returning
>   REFUSED and some other oddities),
> 2) When assigning an IP to lo0 on your RELENG_7 box, the netmask chosen
>   is 255.255.255.255 (0xffffffff) instead of 255.0.0.0 (0xff000000),
>   even though for everyone else this isn't happening.  :-)
>
> You've made a hackfix for the issue in #2 by explicitly putting the
> following line in your /etc/rc.conf:
>
>  ifconfig_lo0="inet 127.0.0.1 netmask 255.0.0.0"
>
> Which also appears to resolve issue #1, is that correct?

Yes, adding an entry in /etc/rc.conf that provides 254 IP's now
reveals:
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        inet6 ::1 prefixlen 128        inet6 fe80::1%lo0 prefixlen 64 
scopeid 0x3        inet 127.0.0.1 netmask 0xffffff00

as opposed to: 0xffffffff.


>
> If that's true, there is greater demons at work here,

LOL. By the time you read this, you will have already read my
/punny/ statement to the same. :)

> or something we
> aren't being told about the configuration.  Again, the IPs in rbldnsd
> zone files have nothing to do with IP addresses or netmasks associated
> with loopback, so I don't see how changing the netmask would fix that.
> It almost sounds as if the rbldnsd software may be written to assume
> they're all related, and I sure hope that isn't the case.

No. I'm more inclined, at this state. To think that since the IP
is defined in the zone file. That it requires the /availability/
of the IP so that it can use it - not unlike the BIND. But, it is
not the BIND, so will have it's own (see; different) way of
management regarding IP<-->name, etc...

Anyway, my /real/ reason for starting all this, was to figure out
why the 2 machines act so differently. I can assure you that I
have spent the entire day attempting to figure out if any
difference had crept into any of the server configs. But could
find none.

Thanks again for all your time and effort.

--Chris H


>
> --
> | 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 |
>
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-- 
panic: kernel trap (ignored)