Date: Tue, 16 Jun 2009 13:36:59 +0200 From: Erik Trulsson <ertr1013@student.uu.se> To: saravana perumal <seesaravanan@yahoo.co.in> Cc: FreeBSD Mailer List <freebsd-net@freebsd.org> Subject: Re: TCP Free-BSD setup behaviour. Message-ID: <20090616113659.GA99604@owl.midgard.homeip.net> In-Reply-To: <925929.71164.qm@web8315.mail.in.yahoo.com> References: <925929.71164.qm@web8315.mail.in.yahoo.com>
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On Tue, Jun 16, 2009 at 04:37:32PM +0530, saravana perumal wrote:
> Hi=A0 Louie.
> =A0
> As per Testing=20
> =A0
> 1.Sending SYN and reaching the SYN_SENT state INTIALLY [Active open]
> 2. Then Expects to RECEIVE SYN packet and=20
> 3. To Send SYN & ACK=A0 to reach=A0 SYN-RCVD state.
That does not sound quite correct. The normal sequence for the TCP
three-way handshake is:
-----> SYN
<----- SYN+ACK
-----> ACK
while you for some reason seem to be expecting
-----> SYN
<----- SYN
-----> SYN+ACK
which is not what I would expect.
> =A0
> In Free BSD active SYN-RCVD state is not happening .
> =A0
> In TCP state tranistion my expectation is represented for SYN_RCVD state.
> =A0
> =A0
> Thanks.
> Saravanan
>=20
>=20
> --- On Tue, 6/16/09, saravana perumal <seesaravanan@yahoo.co.in> wrote:
>=20
>=20
> From: saravana perumal <seesaravanan@yahoo.co.in>
> Subject: Re: TCP Free-BSD setup behaviour.
> To: "Louis Mamakos" <louie@transsys.com>
> Cc: "FreeBSD Mailer List" <freebsd-net@freebsd.org>
> Date: Tuesday, June 16, 2009, 3:15 PM
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> Hi Louie
> =A0
> =A0We are trying to make Active Sync Received state.
> =A0
> As per our testing we are trying to received Syn packet from APPLICATION =
end and to send syn & ACK from Device END and hence reaching the ACTIVE SYN=
-RECEIVED state.
> =A0
> So initially make the application to send SYN sending the Initial SYN and=
once Received the SYN packet , expecting the Device to Send SYN & ACK
> =A0
> I hope the expectation should be rite in case of ACTIVE-SYN received Stat=
e.
> =A0
> Thanks.
> Saravanan
> =A0
>=20
>=20
> --- On Tue, 6/16/09, Louis Mamakos <louie@transsys.com> wrote:
>=20
>=20
> From: Louis Mamakos <louie@transsys.com>
> Subject: Re: TCP Free-BSD setup behaviour.
> To: "saravana perumal" <seesaravanan@yahoo.co.in>
> Cc: freebsd-net@freebsd.org, sarbalas@gmail.com
> Date: Tuesday, June 16, 2009, 3:05 AM
>=20
>=20
>=20
> On Jun 15, 2009, at 3:44 AM, saravana perumal wrote:
>=20
> > Hi Louie ,
> >=20
> >=20
> > Thanks for the Response on my Queries.
> >=20
> > For QUERY 3,
> > ACTIVE open frm Free BSD end:
> >=20
> >=A0 =A0 =A0 =A0 FREE BSD=A0 =A0 =A0 =A0 =A0 APPLICATION
> >=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0=A0Send ---------> syn
> >=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0=A0Receive <-------- SYN
> >=20
> > Expect SYN & ACK-------------> Getting only ACK in this Scenario,
> >=20
> >=A0 Now Expects FREE BSD to respond back with the SYN & ACK , but BSD is=
sending only ACK message as the response.
>=20
> There's no reason why the FreeBSD host would send another SYN; presumably=
the "APPLICATION" host received the SYN and responds back with SYN of it's=
own and ACK of the FreeBSD host's SYN.=A0 Once the SYN has been ACK'd, the=
re's no reason to resend it.=A0 I suppose I wonder why you expect the FreeB=
SD system to retransmit it's SYN?
>=20
> > 4=A0 =A0 .When checking the State - TIME-WAIT=A0 =A0 Sending FIN and ex=
pecting the ACK ;Getting the ACK properly.=A0=A0=A0Sending Data Segment and=
Expecting the RST signal not getting the RST ; Instead DUT is sending the =
Last TCP packet. Issue seen only in Free BSD
> >=20
> >=20
> > For this Issue mentioned above, Last TCP packet is jst a Testing packet=
with the
> > following Field set=A0 in TIME-WAIT state ,
> >=20
> >=20
> > TCP: ---- TCP Packet ----
> > TCP:
> > TCP: Source Port=A0 =A0 =A0 =A0 =A0=A0=A0=3D 16815 (16815)
> > TCP: Destination Port=A0 =A0 =A0 =3D 16816 (16816)
> > TCP: Sequence Number=A0 =A0 =A0=A0=A0=3D 3865716731 (0xE66A27FB)
> > TCP: Acknowledgment Number =3D 0 (0x00000000)
> > TCP: Data Offset=A0 =A0 =A0 =A0 =A0=A0=A0=3D 5 (20 bytes)
> > TCP: Reserved=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D 0
> > TCP: Control Bits=A0 =A0 =A0 =A0 =A0 =3D 0x10
> > TCP:=A0 |543210
> > TCP:=A0 |0.....=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D Urgent Pointer Isn't Sig=
nificant
> > TCP:=A0 |.1....=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D Acknowledgment Is Signif=
icant
> > TCP:=A0 |..0...=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D No Push Function
> > TCP:=A0 |...0..=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D No Reset Connection
> > TCP:=A0 |....0.=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D No Synchronize Sequence =
Numbers
> > TCP:=A0 |.....0=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D More Data From Sender
> > TCP: Window=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D 32752 bytes
> > TCP: Checksum=A0 =A0 =A0 =A0 =A0 =A0 =A0 =3D 0x41A0 (Correct)
> > TCP: Urgent Pointer=A0 =A0 =A0 =A0 =3D 0 (Not Significant)
> > TCP:
> > TCP: --- Trailing Data [12 bytes] ---
> > TCP:=A0 53 61 6D 70 6C 65 20 44 61 74 61 00=A0 =A0 =A0 =A0 =A0 =A0 =A0=
=A0=A0Sample Data.
> > TCP: --- Trailing Data End ---
> > From machine Sending=A0 to the FREE BSD machine,
> >=20
> > This is to verify that Free BSD is in TIME-WAIT state.
>=20
> Not sure what good this packet trace is; the only reason the TCP would re=
spond with a RST segment is if the segment it receives is somehow bogus.=A0=
Perhaps that the send sequence is outside the window.=A0 If the data is wi=
thin the window, it might be considered an "old" segment that happens to ar=
rive, perhaps out-of-order; why would the local TCP reset the connection fo=
r no good reason?
>=20
> louie
>=20
>=20
>=20
>=20
>=20
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--=20
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se
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