So I have a configuration where I have pfSense running on a server and a single Cisco Switch. I thought it would be convenient to use the serial port on the server (pfSense) to console into the Cisco Switch for remote configuration (as an alternative to SSHing into the switch, in case it is down).
After enabling SSH access, SSH to the pfSense box. Press 8 for shell access.
So the key is just to install some terminal tty console application, I chose screen. Install using the built in package management system:
pkg install screen
Now to connect to the Cisco Switch (u0 was the first (and only) serial, 9600 is default baud rate on Cisco Console Ports:
/usr/local/bin/screen /dev/ttyu0 9600
Interestingly, screen didn’t work without the full path (despite /usr/local/bin being in my path). I may have needed to relog, or it may be a security feature. More investigation needed.