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Hello Thomas, dear all,

please see my comments below.
I am CC'ing TSVWG to discuss this: does this open up a possibility
for DoS attacks ?

On Thursday, 14. February 2002 08:56, Hollaus Thomas wrote:
> Dear all,
>
> Question to unexpected chunks with invalid mandatory parameters (e.g.
> MIS=0, OS=0, Init-Tag=0):
> As far as I understand the sctp.de implementation, it is possible to attack
> a running association with e.g. an INIT and invalid mandatory parameters.
> After receive of that unexpected chunks the prototype does delete the
> running association (pre 16: sctp-control.c, func scr_init, line 677). Is
> that a correct behaviour according to RFC?

The implementation probably should return an ABORT with an Error Chunk
that specifies the appropriate error code, as per RFC 2960:
Cause Code
Value Cause Code
--------- ----------------
1 Invalid Stream Identifier
2 Missing Mandatory Parameter
3 Stale Cookie Error
4 Out of Resource
5 Unresolvable Address
6 Unrecognized Chunk Type
--> 7 Invalid Mandatory Parameter
8 Unrecognized Parameters
9 No User Data
10 Cookie Received While Shutting Down

However, I am not actually sure that this is a good idea, since that
would make it easily possible (with IP spoofing) to start
denial-of-service attacks.
I think the rationale behind this in the RFC was to stop a broken
client from keeping retransmitting wrong INITs and tell it directly
WHAT is wrong, and that something is wrong.

Regards,
Andreas

- --
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Dipl.-Ing. Andreas Jungmaier | _
Computer Networking Technology Group | ASCII ribbon campaign ( )
University of Essen | - against HTML email X
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• [SCTP-Discussion] receive of unexpected chunks with invalid parameters, Hollaus Thomas, 02/14/2002
  • Possible DoS in SCTP ? (was: [SCTP-Discussion] receive of unexpected chunks with invalid parameters), Andreas Jungmaier, 02/14/2002
    • Re: [Tsvwg] Possible DoS in SCTP ? (was: [SCTP-Discussion] receive of unexpected chunks with invalid parameters), Randall Stewart, 02/14/2002
      • [SCTP-Discussion] Re: [Tsvwg] Possible DoS in SCTP ? (was: reception of invalid parameters), Andreas Jungmaier, 02/14/2002
        • [SCTP-Discussion] Re: [Tsvwg] Possible DoS in SCTP ? (was: reception of invalid parameters), Randall Stewart, 02/14/2002
          • [SCTP-Discussion] Re: [Tsvwg] Possible DoS in SCTP ?, Andreas Jungmaier, 02/14/2002
            • [SCTP-Discussion] Re: [Tsvwg] Possible DoS in SCTP ?, Randall Stewart, 02/14/2002
              • [SCTP-Discussion] Re: [Tsvwg] Possible DoS in SCTP ?, Andreas Jungmaier, 02/14/2002

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