NMEAdesync

NMEAdesync is a tool which will output NMEA sentences to stdout. Using socat you can redirect this output to NTPd and move time. NMEAdesync will be first prensented during a conference talk at BSidesCBR 2017.

NMEAdesync will send NMEA senetences with a spoof time to NTPd and also a spoofed PPS

Requirements

NTPd using NMEA data over serial as the time, with PPS for accuarete timing. I set up a Pi using this guide.

Running

1. Configure the options in NMEAdesync.cfg
2. Connect to the PPS wire to GPIO pint 25
3. sudo rm /dev/gps0
4. socat -d -d pty,raw,echo=0 "exec:/home/pi/NMEAdesync.py,pty,raw,echo=0"
5. Note the pts number as will need to use it in the next step
6. sudo ln -s /dev/pts/1 /dev/gps0
7. Notice the time has changed
8. Check pps sudo ppstest /dev/pps0