[Beowulf] ssh connection passwordless

Reuti reuti at staff.uni-marburg.de
Tue Mar 24 03:29:40 PDT 2009


Am 19.03.2009 um 10:22 schrieb Francesco Pietra:

> I have a computing machine and a desktop ssh passwordless
> interconnected through a Zyxel router (which is dhpc on Internet). I
> have now added a second computing machine. I am unable to get all
> three machines passwordless interconnected at the same time. Just only
> two. If I want to have the third computer passwordless connected to
> one of the other two, I have to exchange id_rsa.pub between the two
> again. Mistake or intrinsic feature of ssh?
> What I did:
> (1)generating  the keys with "ssh-keygen -t rsa"
> (2) getting "reserved" the machines on the router
> (3)scp id_rsa.pub to the "authorized_keys"

- you can have more than one line in the authorized keys file, hence  
put there the id_rsa.pub from all other nodes in addition.

- when you need this only for interactive work, you can have a local  
ss-agent running on your desktop and put in ~/.ssh/config and on both  
node a two lines:

Host *
     ForwardAgent yes"

good explanation you can find here: http://unixwiz.net/techtips/ssh- 

- another option might be to setup /etc/ssh/ssh_known_hosts on your  
two compurte nodes to include per line the short hostname, the FQDN,  
the TCP-IP address besides the other hosts ssh keys (not the user's  
one) as this would avoid any password or adding of the machines to  
you personal ~/.ssh/known_hosts file. This won't work with your  
workstation of course as it's TCP/IP address varies.

-- Reuti

> It is also mandatory that asking the "date" to the other computer
> (slogin ... date), the date is given without asking the password. That
> is an issue of a computational code that for its internal
> parallelization needs that (I have not investigated why).
> thanks
> francesco
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