NatHolePunch.exe exit with [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: if don’t have any terminal attached and in the systemd unit is needed to specify StandardInput, TTYPath and optinally for see the logs StandardOutput.

Here is an example, nathole is my unprivileged system user:

# /etc/systemd/system/nathole.service
[Unit]
Description=Forge Networking Nat Hole Punch Server
After=syslog.target network.target

[Service]
User=nathole
Group=nathole
Environment="PATH=/home/nathole/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/snap/bin"
ExecStart=/home/nathole/bin/NatHolePunch.exe
WorkingDirectory=/home/nathole/bin
StandardInput=tty
TTYPath=/dev/tty2
StandardOutput=journal+console