Fixing - Error: bad packet template :-)
wget https://github.com/scriptzteam/masscan-openVPN/blob/main/src/templ-pkt.c
mv templ-pkt.c into your /masscan/src/ folder
make
make install
Test:
openVPN ip - 1.2.3.4
real server ip - 5.6.7.8
Get your router ip
ip route
Sample:
masscan 9.10.11.12 -p22 -e tun0 --router-ip 10.8.0.1
In tcpdump port 22 on scanned server with masscan is openVPN ip :-)