Re: 2.0 ethX bogus packet size messages ...

Paul Gortmaker (gpg109@rsphy6.anu.edu.au)
Sun, 16 Jun 1996 17:21:09 +1000 (EST)


> Also note correct oversized packets dumped onto a network break certain
> well known vendors 8390 based drivers.

And some 2Mbit WAN links, or so I was told.... B-)

Well, as things stand, with linux-8390 and a too-large MTU, the packets
actually *do* hit the wire. (The linux 8390 drivers only moan when Rx'ing
them.) I haven't investigated what other linux drivers & NICs do when
asked to spit out a giant bogon. They may grenade rather un-gracefully,
or simply send the packet as asked, just like the 8390 cards do.

> > Alan, I think the following patch (to use your dev->change_mtu) to keep
> > ether users honest, is probably a good idea.
>
> We could do, but to be honest I dont think we should stop people. Its not
> possible to make a computer luserproof. This is something only root can do
> and its far less fatal than rm -rf /, which is allowed

True, but "rm -rf /" is like burning your *own* house down, wheras
allowing giant packets onto the wire is like sprinkling your whole
street with a big box of nails and broken glass.

RFC793 -- "be conservative in what you do, be liberal in what you
accept from others." <grin>

Paul.