I need to connect to a single serial port over the network. I was wondering if there was a hardware device that I could connect to the port and then install a virtual COM port on a Windows box. The device would need some type of basic security - either IP filtering or authentication or both. Otherwise, I just need a basic 9600 8-N-1 connection.
There are tons of Serial over Ethernet devices available, with wildly varying feature sets.
Just one example for a manufacturer: http://www.perle.com/products/Serial-to-Ethernet.shtml
I've had good luck with the Digi Line of products. They have had decent security - at the very least user based authentication, and ssh access. I have to caveat this with i have never used there 1/2 port models just their higher end 16/32 port models so I can't speak directly to the capabilities of the smaller models.
There are multiple products that will allow you to connect to console ports via terminal emulators:
Note that these products are mainly aimed at managing large numbers of devices; if you just need one connection, there may be other more cost effective alternatives.