too many open files errors

The IOC Shell is cluttered with the following errors:

CAS: Client accept error was "Too many open files"
Cannot open /tmp/ssh_monitor_asubrecord_...: Too many open files.

When trying to caget any PV, e.g. a PV called pv:name, the following message is returned:

Channel connect timed out: 'pv:name' not found