Serial line sniffer (slsnif).
slsnif is a serial port logging utility. It listens to the specified serial port and logs all data going through this port in both directions.
I get an error: Failed to open a pty: No such file or directory It seems that it only works with the "legacy" pseudo-terminals such as /dev/ttyp0 etc, and not the newer Unix 98 pty system. The program needs an update to support this.