Bad handling of .0 and .255 addresses

From: Christopher E. Brown (cbrown@denalics.net)
Date: Mon May 15 2000 - 17:22:45 EST


I don't know if this applies to 2.2.x, and don't have a setup to test
it with 2.2.x but...

        I have a 2.0.36 router doing evil things to .0 and .255
addresses *not* directly to the machine.

        A router *should* respond/block traffic to network and
broadcast addresses on *local* networks, and it does this.

        A router *should* pass through traffic to network and
broadcast addresses that are *not* local, leaving the last hop router
to respond/block traffic to a network address or broadcast address.
It only does this correctly for *non* .0 and .255 addresses.

        The box is always blocking the first and last address of old
classful networks, even if it is not the last hop router. Unless I am
missing somthing here this is not correct.

        The fun thing is, I have a /24 for dialin use, with a /27 and
/28 delivered to each 48 port dialin unit. The portmasters have
addresses in a /28 withing a different /24.

The routes for the first unit look like

x.x.171.0 x.x.170.98 255.255.255.224 UG 0 0 55 eth2
x.x.171.32 x.x.170.98 255.255.255.240 UG 0 0 39 eth2

        The router is bouncing traffic for x.x.171.0, *as if* it were
a local network. Traffic to x.x.171.32 passes fine.

        If traffic to x.x.171.0 it should be done by the last hop
router (in this case a portmaster) *not* anoth box in the chain.

        Questions? Comments? Help?

---
As folks might have suspected, not much survives except roaches, 
and they don't carry large enough packets fast enough...
        --About the Internet and nuclear war.

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