Re: [uml-devel] uml_switch

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

Alle 12:55, giovedì 23 ottobre 2003, Nelio Pereira ha scritto:
> Hi list..
>
> I'm using UML to benchmark a distributed protocol
> (cluster membership service) on a virtual network. As
> a way of injecting faults, I thought about changing
> uml_switch so it would not forward every message it
> receives. Roughly speaking, it could deliver only a
> percentage of the messages.

Just use iptables. It's simpler. Download patch-o-matic: then use either 
base/nth.patch or base/random.patch(the second is maybe better) for the 
kernel that will have to support this new option. Then, to filter it, you 
must find a point where to apply the rule. I think the simpler one is to set 
up a bridge as specified for TUN/TAP in the networking page and then add the 
rule on the host FORWARD chain adding -i(or -o) br0. Or maybe, you should add 
it somewhere else(for instance, just use tap devices without a bridge, then 
add that rule with -i tap+ and -o tap+ on FORWARD: it will match packets 
being forwarded on the host between UML's).
>
> I would like to know where in the uml_switch code is
> the best place to do that. Actually, I'd like to
> intercept those messages in a place where I could know
> the sender and recipient IP of each message.

-- 
cat <<EOSIGN
Paolo Giarrusso, aka Blaisorblade
Linux Kernel 2.4.21/2.6.0-test on an i686; Linux registered user n. 292729
EOSIGN



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