I recently constructed a small Beowulf cluster out of some old computers all running Linux Ubuntu 12.04 LTS and have been following the instructions on this page:
So far all has been going well as far as nfs and pinging the other nodes but now I can't get ssh to work without a password. I spent many hours reading other pages on people with similar problem yet none of the things that helped them seem to help me (changing to 600 mode, editing sshd_configure file, etc).
eventually I just moved on to the rest of the steps hoping I might just be able to enter the password at the execution of the task and that does work if it's only one computer running the task (because it asks for mpiuser@node1's password and I can just enter it in) but as soon as I try running the task (the cpi program mentioned later in that document for testing the cluster) on more that one node it (not to surprisingly) asks for the password for both nodes, which is the same, and I enter it but then it just freezes, I think it has something to do with how it asks (it just lists them: password for mpiuser@node1: password for mpiuser@node2: password for mpiuser@node3: etc.)
I've even tried uninstalling and re-installing ssh and nothing happened, the ssh-keygen command seems to work fine (it says everything everyone else's supposedly says) but then it doesn't do anything. I was able to get ssh to work with a password because I found that ssh's default password is the root password so I just changed that but otherwise the ssh-keygen command doesn't seem to do anything.
"ssh -v mpiuser@node1" it says: master@master:~$ su mpiuser **Password:** mpiuser@master:/home/master$ cd mpiuser@master:~$ ssh -v mpiuser@node1 OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to node1 [192.168.0.201] port 22. debug1: Connection established. debug1: identity file /home/mpiuser/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: identity file /home/mpiuser/.ssh/id_rsa-cert type -1 debug1: identity file /home/mpiuser/.ssh/id_dsa type -1 debug1: identity file /home/mpiuser/.ssh/id_dsa-cert type -1 debug1: identity file /home/mpiuser/.ssh/id_ecdsa type -1 debug1: identity file /home/mpiuser/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1.1 debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 54:0e:8b:52:4d:41:08:fe:0b:bc:95:e5:93:42:59:40 debug1: Host 'node1' is known and matches the ECDSA host key. debug1: Found key in /home/mpiuser/.ssh/known_hosts:1 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/mpiuser/.ssh/id_rsa debug1: Authentications that can continue: publickey,password debug1: Trying private key: /home/mpiuser/.ssh/id_dsa debug1: Trying private key: /home/mpiuser/.ssh/id_ecdsa debug1: Next authentication method: password mpiuser@node1's password: