If you use DE10_Nano_Xfce.img, you can do as follows:
1. Use a J45 net cable to connect PC and DE1-Nano board
2. Power on the board to boot the image
3. Type root to login the linux system
4. Type enter KEY as the system password
5. Check the DE10-Nano board IP with ifconfig
6. Open the SoC EDS Command Shell, check the PC IP with ipconfig
7. If the PC IP and board IP are not in a segment, then, you need change either of them. For example, my PC IP is 192.168.0.107, then I change my board IP to 192.168.0.2 with command: ifconfig eth0 192.168.0.2