Sheepdog uses SSH to connect to the GridEngine cluster head. There are a few issues that may come up in the process.

SSH Keys

Sheepdog will only use SSH keys to connect to the remote server. If you don’t already have these set up, it is simple to do so:

local$ ssh-keygen
local$ ssh-copy-id remote

Additionally the keys should either be passphraseless (inadvisable) or stored in an SSH agent, which Sheepdog will use automatically. Most operating systems will automatically set up an SSH agent for you, and you can either connect to the host manually to add the key to the agent, or use ssh-add.

Sheepdog will automatically find a key named id_rsa or id_rsa in ~/.ssh, or you can set ssh_keyfile to a path to the (passphraseless) key file to use. The best way is still to use an SSH agent, though!

Known Hosts

Sheepdog uses Paramiko to connect to SSH servers, and instructs it to read your ~/.ssh/known_hosts file to collect information on host keys. It does not permit it to connect without a valid known host key.

However this can cause issues on remote hosts which use ECDSA keys and also offer an RSA key. In this case Paramiko will (at time of writing) request the RSA key, fail to find it in your known_hosts (which is likely to only contain the ECDSA key) and refuse to connect to the server.

One workaround for this problem is to fetch the RSA key of the server and place it into your known_hosts, for instance:

local$ ssh remote ssh-keyscan -t rsa remote >> ~/.ssh/known_hosts
local$ ssh-keygen -H

SSH Config

If a file ~/.ssh/config exists, Sheepdog will use Paramiko to read this file and use it to determine hostnames, usernames and ports to connect to. In addition, ProxyCommand directives will also be followed. No other configuration parameters are used.

If a hostname, username or port is found in the SSH config that matches the provided hostname, they will be used in preference to the ssh_user and ssh_port configuration options.