Linux Ethernet Bridging - Apr 2007 - [Bridge] control packet flow

Greetings all.
 
I need a transparent way of selectively controlling packet flow between two
network devices such that for example I can "see" [e.g. tcpdump] a
packet coming into eth0, queue it, and then manually release it out eth1, one
packet at a time.  See diagram below.  (Reason for doing this is to watch the
behavior of the device under test to certain packets but I cannot control the
speed of the packets from the traffic source so I need an intermediary to do
that).
 
[PC/traffic initiator] -- [bridge] -- [device under test]
 
I've looked at nistnet, but that would only work for IP packets, and
requires you to use it as a router as I understand it, which wouldn't work
here.  I've also looked at IET which seemed to be what I need, but unless
I'm doing something wrong it crashes very badly under RHAT 9.0 and SuSE 9.0.
 
Is there any simple way to write a 'hook' into bridge-utils or the
kernel to do this?  Are there any other utilities anyone can point me to?
 
Any help would be greatly appreciated!  Thanks in advance!!!

		
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On Mon, 21 Jun 2004 10:06:32 -0700 (PDT)
hell know <sp0ck1701@yahoo.com> wrote:
> Greetings all.
>  
> I need a transparent way of selectively controlling packet flow between two
network devices such that for example I can "see" [e.g. tcpdump] a
packet coming into eth0, queue it, and then manually release it out eth1, one
packet at a time.  See diagram below.  (Reason for doing this is to watch the
behavior of the device under test to certain packets but I cannot control the
speed of the packets from the traffic source so I need an intermediary to do
that).
>  
> [PC/traffic initiator] -- [bridge] -- [device under test]
>  
> I've looked at nistnet, but that would only work for IP packets, and
requires you to use it as a router as I understand it, which wouldn't work
here.  I've also looked at IET which seemed to be what I need, but unless
I'm doing something wrong it crashes very badly under RHAT 9.0 and SuSE 9.0.
>  
> Is there any simple way to write a 'hook' into bridge-utils or the
kernel to do this?  Are there any other utilities anyone can point me to?
>  
> Any help would be greatly appreciated!  Thanks in advance!!!
Two ways I have used are using netfilter bridge tables (ebtables) to label
or control what goes through.  You could route it out to your application then
re-inject it.  Of course if your doing only that you probably want to use
something
like tun or tap .

If you want to do things that change packet speed,
you need to look at the QoS scheduling methods for devices.