32.4.2 Setting Up Your Remote Shell and Secure Shell Clients

For cluster computing on Linux or UNIX systems, most parallel versions of ANSYS FLUENT will need the user account set up such that you can connect to all nodes on the cluster (using either the remote shell ( rsh) client or the secure shell ( ssh) client) without having to enter a password each time for each machine.

Provided that the appropriate server daemons (either rshd or sshd) are running, this section briefly describes how you can configure your system in order to use ANSYS FLUENT for parallel computing.

Configuring the rsh Client

The remote shell client ( rsh), is widely deployed and used. It is generally easy to configure, and involves adding all the machine names, each on a single line, to the .rhosts file in your home directory.

If you refer to the machine you are currently logged on as the `client', and if you refer to the remote machine to which you seek password-less login as the `server', then on the server, you can add the name of your client machine to the .rhosts file. The name could be a local name or a fully qualified name with the domain suffix. Similarly, you can add other clients from which you require similar access to this server. These machines are then "trusted" and remote access is allowed without the further need for a password. This setup assumes you have the same userid on all the machines. Otherwise, each line in the .rhosts file would need to contain the machine name as well as the userid for the client that you want access to. Please refer to your system documentation for further usage options.

Note that for security purposes, the .rhosts file must be readable only by the user.

Configuring the ssh Client

The secure shell client ( ssh), is a more secure alternative than rsh and is also used widely. Depending on the specific protocol and the version deployed, configuration involves a few steps. SSH1 and SSH2 are two current protocols. OpenSSH is an open implementation of the SSH2 protocol and is backwards compatible with the SSH1 protocol. To add a client machine, with respect to user configuration, the following steps are involved:

1.   Generate a public-private key pair using ssh-keygen (or using a graphical user interface client). For example:

   % ssh-keygen -t dsa

where it creates a Digital Signature Authority (DSA) type key pair.

2.   Place your public key on the remote host.

• For SSH1, insert the contents of the client ( ~/.ssh/identity.pub) into the server ( ~/.ssh/authorized_keys).

• For SSH2, insert the contents of the client ( ~/.ssh/id_dsa.pub) into the server ( ~/.ssh/authorized_keys2).

The client machine is now added to the access list and the user is no longer required to type in a password each time. For additional information, consult your system administrator or refer to your system documentation.