How to Access the MCC Cluster (SSH)

Secure Shell (SSH) Method:

The "ssh" command (SSH protocol) is the standard way to connect to MCC. SSH also includes support for the file transfer utilities scp and sftp. Wikipedia is a good source of information on SSH. SSH is available within Linux and from the terminal app in the Mac OS. If you are using Windows, you will need an SSH client that supports the SSH-2 protocol: e.g. Bitvise, OpenSSH, PuTTY, or SecureCRT or MobaXterm. Initiate a session using the ssh command or the equivalent; from the Linux command line the launch command looks like this:

localhost$ ssh myusername@mcc.uky.edu

The above command will rotate connections across all available login nodes and route your connection to one of them. To connect to a specific login node, use its full domain name:

localhost$ ssh myusername@mcclogin1.ccs.uky.edu (For login1 node)
localhost$ ssh myusername@mcclogin2.ccs.uky.edu (For login2 node)

Access the MCC DTN node:

localhost$ ssh myusername@mcc-dtn.ccs.uky.edu

If you experience problems when using SSH, such as dropped or unresponsive connections, you may need to adjust some settings in your SSH client to keep SSH session alive.

For Windows: (Putty)

1. Start PuTTY.
2. Load your connection session.
3. In the Category pane, click Connection.
4. Under Sending of null packets to keep session active, in the Seconds between keepalives, type 240.
   With this configuration, PuTTY sends a packet to the server every 240 seconds (4 minutes) to keep the connection alive.
5. In the Category pane, click Session.
6. Click Save.
7. Connect to your account and monitor the connection. If it still drops, gradually decreases the keepalive interval until the connection is stable.

Linux and Mac OS X operating systems:

On Linux and Apple Mac OS X operating systems, the ~/.ssh/config file enables you to specify many SSH settings, including those that keep alive an SSH connection. To do this, follow these steps:

1. Use your preferred text editor to open the ~/.ssh/config file on your local computer.
   If the .ssh directory or the config file does not exist, create them.

2. Add the following lines to the config file. The Host value can be any name you want; it is simply a label for the other settings. The Hostname value is the remote host you want to access; replace example.com with your domain name.

   Host example
       Hostname example.com
       ServerAliveInterval 240
       ServerAliveCountMax 2

   • With this configuration, the SSH client sends a packet to the server every 240 seconds (4 minutes) to keep the connection alive.
3. Save the changes to the config file.

Also, make sure to run chmod 600 ~/.ssh/config, because the config file must not be world-readable.