How does ipfw pause outgoing packets? (i.e., Carrafix??)

[Gwailo]

I think the idea of Carrafix is awesome, and I'm curious, from a "Darwin underpinning" as the author purts it, how the data packets have a pause applied to them?

He explains that the upload speed of the local server can be reduced by applying a pause to the outgoing data packets (on a specific port) but not any other packets (i.e., incoming packets) so as to unsaturate one's local bandwidth.

I noticed that he uses ipfw -f flush as a last resort to uninstalling his software, which of course leads me to assume he's using the ipfw to manage the packets.

Anyone know how to do this manually? And possibly, why the application must remain open for the application to work? (Is it probable that he adds rules at application startup and then removes them at application quit?)

Secondly, where could I find a good definition of the terms (echo reply, ICMP, etc) used in the manpage? I'm familiar with most of them, just some of them elude me .

TIA :

 

[lurk]

I have played with ipf on HPUX a fair ammount and if this is similar enough I would assume that he is using a userland process to do the fintering. Whay happens is that a rule is added to pass a given packet out to a user process for filtering that application then decides the packets fate.

From your description it sounds like this might be what he is doing. The user process can then simply delay approving certain packets. Now this is totially conjecture on my part so don't give it too much creedence

-Eric