The user cannot log in to the server at the first attempt and has to try two or three times before being authenticated.

This problem occurs when the server is running on Fedora 20 or 19 with SELinux enabled and the host machine has been restarted. In this case, context for nxserver is wrongly set and system logs (e.g. on Fedora 20 /var/log/audit/audit.log) report two kinds of alerts, one for pulseaudio:

type=AVC msg=audit(1389033815.453:1656): avc:  denied   append for  pid=25046 comm=”pulseaudio” path=”/usr/NX/var/log/nxerror.log” dev=”sdb3″ ino=939026 scontext=system_u:system_r:pulseaudio_t:s0 tcontext=unconfined_u:object_r:usr_t:s0 tclass=file

and one for dbus-daemon:

type=USER_AVC msg=audit(1389033249.408:1645): pid=616 uid=81 auid=4294967295 ses=4294967295  subj=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 msg=’avc:  denied   send_msg for msgtype=method_return dest=:1.287 spid=24590 tpid=24608 scontext=system_u:system_r:fprintd_t:s0 tcontext=system_u:system_r:initrc_t:s0 tclass=dbus  exe=”/usr/bin/dbus-daemon” sauid=81 hostname=? addr=? terminal=?’

A possible solution is to manually fix context for nxserver by running from a terminal:

# chcon -t var_log_t /usr/NX/var/log/nxerror.log

and restarting the server:

# /usr/NX/bin/nxserver --restart