[Beowulf] High Performance SSH/SCP

Robert G. Brown rgb at phy.duke.edu
Thu Feb 14 03:20:57 PST 2008

On Wed, 13 Feb 2008, Douglas Eadline wrote:

> Just saw this mentioned on Slashdot.
> High Performance SSH/SCP - HPN-SSH
> http://www.psc.edu/networking/projects/hpn-ssh/
> The internal flow control buffers in openssh are small
> and static. The guys at Pittsburgh SC have created a
> patch that can be applied to openssh that dynamically increases
> the buffers which dramatically improves performance. They
> also multi-threaded the crypto. So if you were wondering
> about what to do with that extra core, now you have your
> answer.

It would be nice if they would revive the old ssh flag for turning off
encryption altogether.  That alone would make let us all finally and
permanently put a stake through the wicked heart of rsh.  It is fine to
have ssh to the hostauth/userauth handshake, because with rsh one might
as well just openly invite crackers into your system as a user (and with
the kernel bug that I'm hoping everybody has just finished updating,
promotion to root is/was appallingly easy from accounts on a system).
For most computational purposes, though, I could care less if anyone
READS the intermediate traffic.

The openssh folks got a bit hypervigilant going from the old ssh top
openssh.  They also removed the symlink feature of ssh inherited from
rsh, and made it a PITA to background tasks and exit with the tasks

Any idea if the openssh people are going to incorporate the patch
permanently?  Any hope of replacing the "Ciphers none" option (even with
a NoCiphers boolean control on the sshd config that allows a local
sysadmin to disable it for the masses in non-cluster environments) and
restoring control to the actual local sysadmin and user base instead of
preempting the choice?


> --
> Doug
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Robert G. Brown                            Phone(cell): 1-919-280-8443
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