rsh

Chris Samuel csamuel at vpac.org
Tue Sep 23 19:10:30 EDT 2003


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On Tue, 23 Sep 2003 12:40 pm, Jan Schaumann wrote:

> Why?

IMHO rsh/rlogin are inherently insecure (vulnerable to spoofing, password 
sniffing).  We only permit interactive access to our cluster via SSH.

> Most likely, ssh will introduce a non-negligible overhead in encryption
> and/or compression.

Certainly in our environment (Linux, PBS, MAUI, MPICH/GM) the major use of ssh 
internal to the cluster is as a replacement for rsh for starting MPI jobs on 
the various nodes. The impact of any overhead is minor given that the data 
will be shuffled around over Myrinet without using IP.

Compared with the overhead of submitting a job into PBS and having it 
scheduled by MAUI, any extra latency due to SSH disappears into the noise. 
:-)

Chris
- -- 
 Christopher Samuel - (03)9925 4751 - VPAC Systems & Network Admin
 Victorian Partnership for Advanced Computing http://www.vpac.org/
 Bldg 91, 110 Victoria Street, Carlton South, VIC 3053, Australia

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