openssh bugs - Nov 2003 - [Bug 763] Add Null packet keepalive option

http://bugzilla.mindrot.org/show_bug.cgi?id=763

           Summary: Add Null packet keepalive option
           Product: Portable OpenSSH
           Version: 3.7p1
          Platform: All
               URL: http://marc.theaimsgroup.com/?l=openssh-unix-
                    dev&m=98460103932386&w=2
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: ssh
        AssignedTo: openssh-bugs at mindrot.org
        ReportedBy: hauser at acm.org


for those often being disconnected, please add this feature!



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------- Additional Comments From dtucker at zip.com.au  2003-11-23 16:23 -------
See also the (relatively) recent discussion on openssh-unix-dev:
http://marc.theaimsgroup.com/?l=openssh-unix-dev&m=104947194014595



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v at iki.fi changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |v at iki.fi





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------- Additional Comments From v at iki.fi  2003-11-24 01:05 -------
I assume Ralf Hauser invited me to add myself to Cc list of this bug because of
this comment:

http://www.mindrot.org/pipermail/openssh-unix-dev/2003-April/017804.html

So here it is for the record:

  What about the randomness? Isn't there some information exposed currently
as
  to at what time and how many times the user for example presses keys? I
  think there was a proposed attack to record the relative timing of packets
  sent by ssh after each key press and to use that information to analyze what
  kind of password the user might have typed. Inserting random traffic to the
  stream might mitigate this information leak? Or has this been handled by
  other means?

What tried to address with the above comment is what is described in 

  http://www.cs.berkeley.edu/~daw/papers/ssh-use01.ps
  http://www.cs.berkeley.edu/~daw/papers/ssh-use01.pdf
  Dawn Xiaodong Song, David Wagner, and Xuqing Tian,
  "Timing Analysis of Keystrokes and Timing Attacks on SSH",
  10th USENIX Security Symposium, 2001.

  http://www.ece.cmu.edu/~dawnsong/papers/ssh-timing.pdf

A summary:
  http://linux.oreillynet.com/lpt/a/linux/2001/11/08/ssh_keystroke.html





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martin at fatbob.nu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |martin at fatbob.nu



------- Additional Comments From martin at fatbob.nu  2003-11-24 04:19 -------
I would be pleased if this feature was added. I'm patching my OpenSSH
clients
right now with a patch posted to the dev-list a couple of times.

http://marc.theaimsgroup.com/?l=openssh-unix-dev&m=104972406723496&w=2




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djm at mindrot.org changed:

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



------- Additional Comments From djm at mindrot.org  2003-12-16 22:43 -------
This is two issues in one bug: 

1. Client->server keepalive packets
2. Adding fake traffic to frustrate timing analysis

These are very different issues, though one would probably use the solution to
(1) to implement (2). Exactly how to implement (2) is a subject for further
discussion.

In any case, support for (1) is now in CVS (see ServerAliveInterval and
ServerAliveCountMax), so I'll close this bug. I think any traffic analysis
defeat should be thrashed out on openssh-unix-dev@ and filed as a separate bug




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