Subject: Re: illegal network routes and a ponderance
To: None <email@example.com>
From: None <firstname.lastname@example.org>
Date: 02/18/2003 14:56:52
On Tuesday 18 February 2003 13:33, der Mouse wrote:
> >> What's going on here is that the network configuration is inherently
> >> illegal, because the "default gateway" you're being fed isn't on any
> >> network they've allocated you an address on.
> > Whether the network configuration is illegal or not, would it be
> > beneficial to allow this kind of routing?
> *What* kind of routing?
> What would it even _mean_ to have a route pointing to a gateway that's
> not on-net for any configured interface address? Where would you
> expect such packets to be sent? I can't see anything sensible to do
> with them.
The kind of routing where multiple default routes are possible; Where
communicating with an ethernet-connected gateway that isn't in your specific
netmask is simple; where outgoing traffic goes to the logical (as in
sensible) interface it should; where ipfilter rules aren't needed to
short-circuit the routing table.
Thor originally mentioned:
"There are a number of tricks you can use here; all are foul; some may
actually work." -- And then continued on to describe a way to use NAT along
with an IP alias that *was not* allocated to one's own machine to work around
the routing limitations.
By "foul" I suppose he could've just meant foul as in distasteful and
hackish--smelly. But then, of course, that's what we all call Linux when it
does something "incorrectly" or messily. I took "foul" to mean "wrong any way
you look at it."
It's been mentioned that the only reason these kinds of routes exist are
misconfigurations and ancient out-of-date equipment.
If we're discarding out-of-date equipment then why port to the older
If we're inoperable in the face of misconfigurations, then we lose out because
the philosophy appears to be--"Fix the configuration" when that's not always
possible. Forcing purity on ourselves is fine, but all it does it piss
everyone else off. Self-flagellation is (apparently) soul-purifying but when
you turn the whip on people minding their own business, the results can be
My original point was that in the interests of interoperability with networks
where Linux chugs along just fine, perhaps this might be something to look at
rather than forcing the whole network into "correctness" just to add NetBSD
to the lot.
Current Telus ADSL gateways have multiple aliases and in some cases hand out
the wrong gateway for the IP they just leased. I wouldn't say a suddenly
disconnected machine is a big win here.
*Many* ethernet segments are shared by multiple networks. Regardless of how
"correct" such a configuration is, the fact remains that in order to
communicate with these foreign-local networks the NetBSD user must jump
through some pretty crazy friggin' hoops.