openssh bugs - May 2015 - [Bug 2392] New: unable to ssh with umac has algorithm. error:Disconnecting packet:corrupted MAC on input.

https://bugzilla.mindrot.org/show_bug.cgi?id=2392

            Bug ID: 2392
           Summary: unable to ssh with umac has algorithm.
                    error:Disconnecting packet:corrupted MAC on input.
           Product: Portable OpenSSH
           Version: 5.0p1
          Hardware: PPC
                OS: Linux
            Status: NEW
          Severity: critical
          Priority: P5
         Component: sshd
          Assignee: unassigned-bugs at mindrot.org
          Reporter: ramyakrc at gmail.com

Tried to ssh from client(Openssh version 4.7p1) to server(openssh
version 5.0p1) using umac hash algorithm but ssh was disconnected from
server end with the following error."Disconnecting packet:Corrupted MAC
on input".
But ssh from client to server using hmac is successful.


Please confirm whether the error is due to software or hardware
issues.Is there any workaround to resolve the issue.

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Ramya <ramyakrc at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|unable to ssh with umac has |unable to ssh with umac
                   |algorithm.                  |hash algorithm.
                   |error:Disconnecting         |error:Disconnecting
                   |packet:corrupted MAC on     |packet:corrupted MAC on
                   |input.                      |input.

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Ramya <ramyakrc at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 OS|Linux                       |Other

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Darren Tucker <dtucker at zip.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dtucker at zip.com.au

--- Comment #1 from Darren Tucker <dtucker at zip.com.au> ---
You'd need to provide a lot more information before we could even
guess.

What OSes are on each of the client and server?  Compilers?  Hardware? 
Network?

Both versions you cite are quite old although I am not aware of any
bugs affecting umac.

There have been many causes found for this in the past, ranging from
broken hardware, ethernet drivers, network equipment, memory and
compilers.  For some examples see:
https://bugzilla.mindrot.org/show_bug.cgi?id=845

Given that it happens with umac but not hmac, I'd guess it's a compiler
bug, but that's pure speculation.

As for workarounds: hmac seems to not have that problem, why not just
use that?

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Ramya <ramyakrc at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Hardware|PPC                         |ARM

--- Comment #2 from Ramya <ramyakrc at gmail.com> ---
Hi

Client OS ? Linux
Server OS - VxWorks
Compiler  ? gcc compiler
Processor - ARM

We tried to SSH from clent(Linux) to server(VxWorks)with the following
command.
ssh -v -m umac-64 at openssh.com xx.xx.xx.xx

We found that before MAC computation, final value of input
buffer(input) after buffer_consume is Offset as 32 and End as 40.
MAC length was set as 8.

But the computed MAC looks different when compared with the input MAC.
Hence the below error was displayed and SSH was disconnected.
"Disconnecting: Corrupted MAC on input".

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--- Comment #3 from Darren Tucker <dtucker at zip.com.au> ---
I'd be looking at the vxworks side since there are few reports of
problems on Linux x86.  I'd suggest building your vxworks binaries
without optimizations and see if that helps:

$ CFLAGS="" ./configure --target whatever

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--- Comment #4 from Ramya <ramyakrc at gmail.com> ---
Hi,

Tried by disabling optimization while building.
But this did not help.Issue still seen.

We also found that it is working fine when we try to SSH with UMAC hash
algorithm from linux machine(with OpenSSH version 4.7p1) to linux
machine(openSSH version 4.7p1)

But when we try to SSH with umac from linux(OpenSSH version 4.7p1) to 
vxworks(OpenSSH 5.0p1), it fails with the below error.
"Disconnecting packet:Corrupted MAC on input".

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--- Comment #5 from Darren Tucker <dtucker at zip.com.au> ---
Do you have an alternative compiler you could try?
Other than that, I don't have anything else I can suggest.

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|critical                    |normal
                 CC|                            |djm at mindrot.org

--- Comment #6 from Damien Miller <djm at mindrot.org> ---
both 4.7 and 5.0 are really old versions, could you try something more
current?

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WORKSFORME

--- Comment #7 from Damien Miller <djm at mindrot.org> ---
5 months with no followup = no bug

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #8 from Damien Miller <djm at mindrot.org> ---
Close all resolved bugs after 7.3p1 release

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