Ability to interact with a host without packetdrill

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hiren panchasara

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Jun 9, 2015, 8:53:37 AM6/9/15
to packe...@googlegroups.com
Is having packetdrill installed on both hosts still the requirement?
i.e. can I talk to Host B's n/w stack directly with host A's
packetdrill?

Also, does it have a shell like scapy or do I have to put everything into
a script file beforehand?

cheers,
Hiren

Neal Cardwell

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Jun 9, 2015, 8:54:56 AM6/9/15
to hiren panchasara, packe...@googlegroups.com
On Fri, Jun 5, 2015 at 5:28 PM, hiren panchasara
<hi...@strugglingcoder.info> wrote:
> Is having packetdrill installed on both hosts still the requirement?

Yes.

> i.e. can I talk to Host B's n/w stack directly with host A's
> packetdrill?

No. (Not yet!)

> Also, does it have a shell like scapy or do I have to put everything into
> a script file beforehand?

No, there is no interactive shell. The user must construct a script beforehand.

cheers,
neal


> cheers,
> Hiren
>
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Neal Cardwell

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Jun 10, 2015, 4:19:59 PM6/10/15
to hiren panchasara, packe...@googlegroups.com

On Tuesday, June 9, 2015, hiren panchasara <hi...@strugglingcoder.info> wrote:
On 06/09/15 at 08:54P, 'Neal Cardwell' via packetdrill wrote:
> On Fri, Jun 5, 2015 at 5:28 PM, hiren panchasara
> <hi...@strugglingcoder.info> wrote:
> > Is having packetdrill installed on both hosts still the requirement?
>
> Yes.
>
> > i.e. can I talk to Host B's n/w stack directly with host A's
> > packetdrill?
>
> No. (Not yet!)
>
> > Also, does it have a shell like scapy or do I have to put everything into
> > a script file beforehand?
>
> No, there is no interactive shell. The user must construct a script beforehand.

Thanks for the clarifications, Neal.

Please help me clarify one more thing. So, this makes packetdrill a
'verification' tool only, is that correct?

Yes, you could call it testing, verification, etc.
 
Can I induce loss or delay
using packetdrill?

Not exactly. That's not the model. Instead, with packetdrill you make TCP "think" that outgoing packets were lost or delayed by specifying the exact timing and content of each incoming ACK injected into the machine under test. Please read the USENIX paper for details.

If you want to induce loss or delay I recommend netem or dummynet.

neal

hiren panchasara

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Jun 12, 2015, 8:18:55 AM6/12/15
to Neal Cardwell, packe...@googlegroups.com
On 06/10/15 at 04:19P, 'Neal Cardwell' via packetdrill wrote:
> On Tuesday, June 9, 2015, hiren panchasara <hi...@strugglingcoder.info>
> wrote:
>
> > On 06/09/15 at 08:54P, 'Neal Cardwell' via packetdrill wrote:
> > > On Fri, Jun 5, 2015 at 5:28 PM, hiren panchasara
> > > <hi...@strugglingcoder.info <javascript:;>> wrote:
> > > > Is having packetdrill installed on both hosts still the requirement?
> > >
> > > Yes.
> > >
> > > > i.e. can I talk to Host B's n/w stack directly with host A's
> > > > packetdrill?
> > >
> > > No. (Not yet!)
> > >
> > > > Also, does it have a shell like scapy or do I have to put everything
> > into
> > > > a script file beforehand?
> > >
> > > No, there is no interactive shell. The user must construct a script
> > beforehand.
> >
> > Thanks for the clarifications, Neal.
> >
> > Please help me clarify one more thing. So, this makes packetdrill a
> > 'verification' tool only, is that correct?
>
>
> Yes, you could call it testing, verification, etc.

Got it, thank you.
>
>
> > Can I induce loss or delay
> > using packetdrill?
>
>
> Not exactly. That's not the model. Instead, with packetdrill you make TCP
> "think" that outgoing packets were lost or delayed by specifying the
> exact timing and content of each incoming ACK injected into the machine
> under test. Please read the USENIX paper for details.
>
> If you want to induce loss or delay I recommend netem or dummynet.

Thanks a lot for your time. I'll reach out if I have further questions.

Cheers,
Hiren

hiren panchasara

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Jun 12, 2015, 8:18:56 AM6/12/15
to Neal Cardwell, packe...@googlegroups.com
On 06/09/15 at 08:54P, 'Neal Cardwell' via packetdrill wrote:
> On Fri, Jun 5, 2015 at 5:28 PM, hiren panchasara
> <hi...@strugglingcoder.info> wrote:
> > Is having packetdrill installed on both hosts still the requirement?
>
> Yes.
>
> > i.e. can I talk to Host B's n/w stack directly with host A's
> > packetdrill?
>
> No. (Not yet!)
>
> > Also, does it have a shell like scapy or do I have to put everything into
> > a script file beforehand?
>
> No, there is no interactive shell. The user must construct a script beforehand.

Thanks for the clarifications, Neal.

Please help me clarify one more thing. So, this makes packetdrill a
'verification' tool only, is that correct? Can I induce loss or delay
using packetdrill?

Again, thanks for this wonderful tool.

Cheers,
Hiren

Michael Tüxen

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Jun 18, 2015, 4:37:07 PM6/18/15
to packe...@googlegroups.com, ncar...@google.com, hi...@strugglingcoder.info
Not in a way like dummynet or netem. But you can test how a stack reacts
to loss by not injecting a response to it. You can simulate delay by injecting
a packets an RTT after observing the outgoing packet. For example:


+0  < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>

+0  > S. 0:0(0) ack 1 <...>

+.1 < . 1:1(0) ack 1 win 257


lets the SUT think that there is an RTT of 100ms.

Best regards
Michael 
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