I recently did clean installs of Fedora 17.
I then used the Fedora package manager to install the NX 3.5.0 nxclient, nxnode, and nxserver files from the nomachine website.
However, the nxserver service would not start and attempted connections to the nxserver on the machines failed.
I then replaced the default /etc/ssh/sshd_config file from Fedora 17 with the default sshd_config file from a Fedora 16 installation; and after a restart, nxserver now works. Apparently the Fedora 17 default sshd_config file has been munged.
You should see the following:
# /usr/NX/bin/nxserver --status
NX> 900 Connecting to server ...
NX> 110 NX Server is running.
NX> 999 Bye.