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Date:      Fri, 28 Jan 2000 06:11:08 -0800 (PST)
From:      "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net>
To:        roelof@nisser.com (Roelof Osinga)
Cc:        kuzak@kuzak.net (Kuzak), freebsd-stable@FreeBSD.ORG
Subject:   Re: Odd DoS
Message-ID:  <200001281411.GAA81282@gndrsh.dnsmgr.net>
In-Reply-To: <38919B3A.FFA1E70D@nisser.com> from Roelof Osinga at "Jan 28, 2000 02:35:54 pm"

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> "Rodney W. Grimes" wrote:
> > 
> > Fix your netmask on your alias and these will go away.  If your
> > using an IP address as an alias it should have a netmask of 0xffffffff.
> 
> No they don't. Details are in the archives, b.t.w. Nonetheless I
> take it you mean something like:
> 
> ifconfig_ep1="inet 212.187.0.39 netmask 255.255.248.0"
                                                  ^^^^^^
Are you really supernetted here?  This could be a major part of
your problem.  Don't you mean ``255.255.255.248''?

> #used to be
> #ifconfig_ep1_alias0="inet 194.134.130.170 194.134.128.1 netmask
> 255.255.252.0"

The above won't even parse correctly by ifconfig, 2 ip's???? and
again, is this network SUPERNETTED?  Or is the netmask suppose to
actually be 255.255.255.252?

> #according to some:
> ifconfig_ep1_alias0="inet 194.134.130.170 netmask 255.255.255.255"
> #ifconfig_le0="inet 194.134.130.170 netmask 255.255.252.0"
> #defaultrouter="10.0.0.10"
> #defaultrouter="194.134.128.1"
> defaultrouter="212.187.0.1"
> #static_routes="euronet"
> #route_euronet="194.134.0.0 194.134.128.1"
> 
> The only difference is that a -1 netmask results in less ARP
> failures.

And you'll probably get even less if your really have an off by <<8
in your netmask and you fix it...

> 
> Anyway, I think it has been written to facilitate aliassed addresses
> within the same subnet. I.e. all having the same gateway. The above
> is an unforeseen case and that it works at all is a compliment to
> the coder(s).
> 
> Mine is probably a special case, and temporary to boot. I can live
> with the:
> 
>  ...
> arplookup 194.134.128.1 failed: host is not on local network
> arplookup 194.134.128.1 failed: host is not on local network
> file: table is full
> file: table is full
>  ...

What does your routing table look like???

> 
> until the time I can do without the alias. Apparantly, so can
> FreeBSD. It has been 41 days since the last CVSup <g>.
> 
> Having tested most, if not all, permutations possible in the config
> above by commenting and uncommenting appropriate sections; not to
> mention the manual fiddling with routes, ifconfigs and ARP tables
> I do feel justified in pointing out that it might very well be
> caused by having an alias on a different subnet.

I do this all the time to route between 2 subnets on the same
physical ethernet on 1 physical interface on 1 box.  It works
just fine, I don't get bottles of arplookup's unless I blow one
of the netmask some place or a -interface route.

-- 
Rod Grimes - KD7CAX @ CN85sl - (RWG25)               rgrimes@gndrsh.dnsmgr.net


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