sudo apt-get install cmake libx11-dev libxtst-dev libssl-dev qtbase5-dev libglib2.0-dev libgdk-pixbuf-2.0-dev libnotify-dev qttools5-dev qttools5-dev-tools libxkbfile-dev

git clone https://github.com/symless/synergy-core.git
cd synergy-core/
mkdir build
cd build
cmake ..
make -j4

# optionally: 
# sudo apt-get purge cmake libx11-dev libxtst-dev libssl-dev qtbase5-dev libglib2.0-dev libgdk-pixbuf-2.0-dev libnotify-dev qttools5-dev qttools5-dev-tools libxkbfile-dev
# sudo apt-get autoremove

There should now be binaries in the bin directory which you can copy out. Debian package creation not attempted here. I wouldnt recommend it, but i'd assume you could mess your clean image up by doing “sudo make install” outside of package management if you wanted.