Just copy the software from any server that the software exits.

Quoted from the official manual:

The DSSR executable (x3dna-dssr for macOS and Linux, and x3dna-dssr.exe for Windows) is self-contained and does not rely on any third-party libraries. There is no need for any setup or con gurations

• http://x3dna.org/highlights/restraint-optimization-of-dna-backbone-geometry-using-phenix

• copy x3dna-dssr to /home/usr/bin and rename it as dssr

• copy x3dna-snap to /home/usr/bin and rename it as snap