The package consists of two programs - PortRedorector and PortTest.

PortRedirector is a daemon that runs telnet to the remote port of the
terminal server and redirects its input and output to a virtual terminal
device (/dev/pty*). The corresponding slave device (dev/tty*) then can
be used by an application that expects a local async terminal port. For
example, to monitor a UPS (connected to AUX ports on a Cisco router)
using nut.

Whenever telnet subprocess terminates on any reason, it is restarted as
soon as any data received from the terminal device.

It can also work when authentication is required, i.e. it can pass
username and password specified in its configuration file.

PortTest is something like cu(1). You can use either of them to test the
connection.