NX Server products for Linux Operating System are provided as RPM or DEB packages
or tar.gz archives, while NX Server products for Solaris SPARC are provided as
sparc.gz packages. You may install them by using the sudo utility or as superuser (root).
Installation of NX Server requires the download and installation of three packages:
client, node and server. The client is needed because it ships libraries used by the node.
The node is needed because it ships tools needed by the server.
f installation was succesful, the node and server post-install scripts will be
automatically executed in background, without user intervention. The post-install
scripts will perform all the basic configuration steps needed to enable users to
login to the new NX server.
All NX software components are installed under the NX root directory, usually
/usr/NX. This is how your /usr/NX directory should appear after installation:
Basic NX server software components are the nxserver and nxnode command line
tools. They implement terminal server functionalities on top of Linux or any
ther Unix operating system. They are not "daemons", strictly speaking, as they
are activated by the SSH server running on the system. To make a comparison,
they leverage SSH exactly as a Web application using the Apache Web server to
handle communication with clients using the HTTP protocol.
Other NX server software components are the advanced NX proxying agent, nxagent and nxssh.
A NX Client suitable for the target server platform is also needed to handle dialog
boxes inside sessions (or through a remote execution mechanism on clients) and allows
the user to perform basic administrative operations (like killing sessions or displaying statistics).
Basic NX client components are nxclient (a multifunctional GUI manager) and nxssh
(the SSH client used to login to the remote NX server).
On clients, nxauth, which is a command line tool based on xauth, replaces the
standard xauth that comes with X distributions. nxauth is able to handle X
authorization cookies without the need for X11 libraries, saving space in
installation packages.
1.2. NX Libraries Installation Directory
This is how your /usr/NX/lib directory should appear:
# ls -la /usr/NX/lib/
drwxr-xr-x 3 root root 4096 2007-08-02 15:03 .
drwxr-xr-x 9 root root 4096 2007-08-02 15:03 ..
lrwxrwxrwx 1 root root 18 2007-08-03 17:12 libcrypto.so -> libcrypto.so.0.9.8
-rwxr-xr-x 1 root root 1092172 2007-08-03 11:37 libcrypto.so.0.9.8
-rwxr-xr-x 1 root root 22321 2007-05-30 11:31 libesddsp.so.0
-rwxr-xr-x 1 root root 80955 2007-05-30 11:31 libesd.so.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:13 libexpat.so -> libexpat.so.0.4.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:13 libexpat.so.0 -> libexpat.so.0.4.0
-rwxr-xr-x 1 root root 159376 2007-08-03 13:23 libexpat.so.0.4.0
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libfreetype.so -> libfreetype.so.6.3.7
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libfreetype.so.6 -> libfreetype.so.6.3.7
-rwxr-xr-x 1 root root 522904 2007-08-03 13:23 libfreetype.so.6.3.7
lrwxrwxrwx 1 root root 17 2007-08-03 17:12 libjpeg.so -> libjpeg.so.62.0.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:12 libjpeg.so.62 -> libjpeg.so.62.0.0
-rwxr-xr-x 1 root root 126672 2007-08-03 11:37 libjpeg.so.62.0.0
lrwxrwxrwx 1 root root 13 2007-08-03 17:12 libpng12.so -> libpng12.so.0
lrwxrwxrwx 1 root root 19 2007-08-03 17:12 libpng12.so.0 -> libpng12.so.0.1.2.8
-rwxr-xr-x 1 root root 238336 2007-08-03 11:37 libpng12.so.0.1.2.8
lrwxrwxrwx 1 root root 13 2007-08-03 17:13 libX11.so -> libX11.so.6.2
lrwxrwxrwx 1 root root 13 2007-08-03 17:13 libX11.so.6 -> libX11.so.6.2
-rwxr-xr-x 1 root root 904200 2007-08-03 13:23 libX11.so.6.2
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libXcompext.so -> libXcompext.so.3.0.0
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libXcompext.so.3 -> libXcompext.so.3.0.0
-rwxr-xr-x 1 root root 53676 2007-08-03 13:23 libXcompext.so.3.0.0
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libXcomposite.so -> libXcomposite.so.1.0
lrwxrwxrwx 1 root root 20 2007-08-03 17:13 libXcomposite.so.1 ->libXcomposite.so.1.0
-rwxr-xr-x 1 root root 6480 2007-08-03 13:23 libXcomposite.so.1.0
lrwxrwxrwx 1 root root 21 2007-08-03 17:13 libXcompshad.so -> libXcompshad.so.3.0.0
lrwxrwxrwx 1 root root 21 2007-08-03 17:13 libXcompshad.so.3 ->libXcompshad.so.3.0.0
-rwxr-xr-x 1 root root 35668 2007-08-03 13:23 libXcompshad.so.3.0.0
lrwxrwxrwx 1 root root 19 2007-08-03 17:12 libXcompsh.so -> libXcompsh.so.3.0.0
lrwxrwxrwx 1 root root 19 2007-08-03 17:12 libXcompsh.so.3 -> libXcompsh.so.3.0.0
-rwxr-xr-x 1 root root 76732 2007-08-03 11:37 libXcompsh.so.3.0.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:12 libXcomp.so -> libXcomp.so.3.0.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:12 libXcomp.so.3 -> libXcomp.so.3.0.0
-rwxr-xr-x 1 root root 936540 2007-08-03 11:37 libXcomp.so.3.0.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:13 libXdamage.so -> libXdamage.so.1.0
lrwxrwxrwx 1 root root 17 2007-08-03 17:13 libXdamage.so.1 -> libXdamage.so.1.0
-rwxr-xr-x 1 root root 6440 2007-08-03 13:23 libXdamage.so.1.0
lrwxrwxrwx 1 root root 14 2007-08-03 17:13 libXext.so -> libXext.so.6.4
lrwxrwxrwx 1 root root 14 2007-08-03 17:13 libXext.so.6 -> libXext.so.6.4
-rwxr-xr-x 1 root root 65344 2007-08-03 13:23 libXext.so.6.4
lrwxrwxrwx 1 root root 16 2007-08-03 17:13 libXfixes.so -> libXfixes.so.3.0
lrwxrwxrwx 1 root root 16 2007-08-03 17:13 libXfixes.so.3 -> libXfixes.so.3.0
-rwxr-xr-x 1 root root 14432 2007-08-03 13:23 libXfixes.so.3.0
lrwxrwxrwx 1 root root 15 2007-08-03 17:13 libXft.so -> libXft.so.2.1.2
lrwxrwxrwx 1 root root 15 2007-08-03 17:13 libXft.so.2 -> libXft.so.2.1.2
-rwxr-xr-x 1 root root 81436 2007-08-03 13:23 libXft.so.2.1.2
lrwxrwxrwx 1 root root 16 2007-08-03 17:13 libXrandr.so -> libXrandr.so.2.0
lrwxrwxrwx 1 root root 16 2007-08-03 17:13 libXrandr.so.2 -> libXrandr.so.2.0
-rwxr-xr-x 1 root root 10192 2007-08-03 13:23 libXrandr.so.2.0
lrwxrwxrwx 1 root root 19 2007-08-03 17:13 libXrender.so -> libXrender.so.1.2.2
lrwxrwxrwx 1 root root 19 2007-08-03 17:13 libXrender.so.1 -> libXrender.so.1.2.2
-rwxr-xr-x 1 root root 32000 2007-08-03 13:23 libXrender.so.1.2.2
lrwxrwxrwx 1 root root 14 2007-08-03 17:13 libXtst.so -> libXtst.so.6.1
lrwxrwxrwx 1 root root 14 2007-08-03 17:13 libXtst.so.6 -> libXtst.so.6.1
-rwxr-xr-x 1 root root 22608 2007-08-03 13:23 libXtst.so.6.1
lrwxrwxrwx 1 root root 13 2007-08-03 17:12 libz.so -> libz.so.1.2.3
lrwxrwxrwx 1 root root 13 2007-08-03 17:12 libz.so.1 -> libz.so.1.2.3
-rwxr-xr-x 1 root root 69484 2007-08-03 11:37 libz.so.1.2.3
drwxr-xr-x 3 root root 4096 2007-08-03 17:13 perl
libXcomp, the NX transport and compression library, is the core of NX technology.
It implements new semantics of X client-server connections. It allows an X client
like Mozilla, for example, to "listen" for connections from the X server. Or, as
in NX sessions, it enables agents to wait for a clients connections from the NX proxy.
libXcomp also handles compression of X protocol and provides implementation of libXcompext
extensions to the X protocol in a way that is transparent to the real X server.
libXcompext library provides nxagent with a user-friendly wrapper to some of X compression
and optimization capabilities built in libXcomp, while the modified libraries libX11 and
libXext implement NX transport layer functions and other minor optimizations. Among them
is a cleanup of padding bytes of core X protocol requests and images, enhancements that
are vital to compression and caching effectiveness of NX.
libXcompshad library provides nxagent with the screen-exporting functions needed
to implement the desktop sharing functionality, i.e. it provides functions to monitor
the changed areas of the screen (initially on a generic X server, later on Windows and Mac)
and to display the image of the modified areas on a remote X server, by a simple XPutImage.
Other shared libraries shipped by the node package, as libXdamage, libXrandr and
libXrender or shipped by the client package, as libjpeg, libpng and libz ensure
that the NX software can be installed and run on the widest range of Linux
distributions.
The perl directory contains critical perl libraries and modules that NX server
and NX node must find in the target environment.
2. The Other NX Directories
Here is the /usr/NX/etc directory:
# ls -al /usr/NX/etc/
drwxr-xr-x 3 nx root 4096 Aug 6 18:52 .
drwxr-xr-x 9 root root 4096 Aug 6 18:52 ..
-rw------- 1 nx root 0 Aug 6 18:52 administrators.db
-rw-r--r-- 1 nx root 0 Aug 6 18:52 administrators.db.lock
-rw-r--r-- 1 root root 0 Aug 2 15:03 administrators.db.sample
-rw------- 1 nx root 0 Aug 6 18:52 guests.db
-rw-r--r-- 1 nx root 0 Aug 6 18:52 guests.db.lock
-rw-r--r-- 1 root root 0 Aug 2 15:03 guests.db.sample
drwxr-xr-x 2 nx root 4096 Aug 6 18:52 keys
-rw-r--r-- 1 root root 13781 Aug 6 18:52 node.cfg
-rw-r--r-- 1 root root 13268 Aug 3 13:23 node-debian.cfg.sample
-rw-r--r-- 1 root root 13270 Aug 3 13:23 node-fedora.cfg.sample
-r-------- 1 root root 679 Aug 6 18:52 node.lic
-rw-r--r-- 1 root root 13270 Aug 3 13:23 node-mandrake.cfg.sample
-rw-r--r-- 1 root root 13270 Aug 3 13:23 node-redhat.cfg.sample
-rw-r--r-- 1 nx root 0 Aug 6 18:52 nodes.db
-rw-r--r-- 1 root root 13266 Aug 3 13:23 node-suse.cfg.sample
-rw------- 1 nx root 0 Aug 6 18:52 passwords.db
-rw-r--r-- 1 nx root 0 Aug 6 18:52 passwords.db.lock
-rw-r--r-- 1 root root 0 Aug 2 15:03 passwords.db.sample
-rw------- 1 nx root 0 Aug 6 18:52 profiles.db
-rw-r--r-- 1 nx root 0 Aug 6 18:52 profiles.db.lock
-rw-r--r-- 1 root root 0 Aug 2 15:03 profiles.db.sample
-rw-r--r-- 1 root root 22108 Aug 6 18:52 server.cfg
-rw-r--r-- 1 root root 22108 Aug 2 15:03 server-debian.cfg.sample
-rw-r--r-- 1 root root 22108 Aug 2 15:03 server-fedora.cfg.sample
-r-------- 1 nx root 673 Aug 6 18:52 server.lic
-rw-r--r-- 1 root root 22108 Aug 2 15:03 server-mandrake.cfg.sample
-rw-r--r-- 1 root root 22108 Aug 2 15:03 server-redhat.cfg.sample
-rw-r--r-- 1 root root 22108 Aug 2 15:03 server-suse.cfg.sample
-rw------- 1 nx root 0 Aug 6 18:52 users.db
-rw-r--r-- 1 nx root 0 Aug 6 18:52 users.db.lock
-rw-r--r-- 1 root root 0 Aug 2 15:03 users.db.sample
The etc directory contains the NX server and NX node configuration files, i.e.
server.cfg and node.cfg, the NX databases for managing users and nodes, and the
SSL keys, stored in the keys subdirectory, used by the server to access the node's
resources on behalf of NX users.
Using the NX terminology, a node is the host that runs user sessions. In the case
of NX Advanced Server product, there can be multiple nodes, while in all the other
NX Server implementations only one node is present in the system, where the NX Server
have been installed.
The var/db directory contains either the sessions databases and some temporary files
used, for example, to send messages to some or all running sessions, while the var/log
directory contains log files produced during the installing or updating of the NX node and
server. Finally, the var/run directory is used to store pids of the running daemons, as
for example nxsensor and nxstat, used to elaborate NX statistics about either the host
machine and the NX sessions. These statistics are displayed via the NX Server Manager Web
tool.
The share directory contains images and icons used by NX Client. The share/documents directory,
instead, is used to store all the documents provided by the NX software products, as the NoMachine
EULA and additional information to activate, for example, the CUPS backend.
The scripts/init directory contains those scripts to start and stop the server and the other NX
daemons, as nxstat, at machine reboot/shut-down. The privileged scripts run by NX server to perform
opearions that requires administrative privileges are stored in the scripts/restriced directory.
While the NX node and server setup scripts are available in the scripts/setup directory.
The last directory is home. It is the home directory of nx user. The nx user is the account
used by NX server to perform most operations. It corresponds to user nobody or www of Apache
web server. The nx account is unprivileged. This ensures that in case of severe malfunctions
of NXs software or exploited security bugs, an attacker cannot take control of the whole server.
3. The User NX Directory
NX Client uses the .nx directory in the user's home directory to store all its
configuration files. This same directory is used by NX server to store temporary
files and the session logs at the time a new session is being run. The User NX
directory on client side can be configured via the NX Client GUI -> Environment
panel, while, on server side, the NX node configuration file allows to specify
a .nx directory different that the default one.
Lets go through the .nx directory of the guest user test0766 on NoMachine TestDrive:
test0766@test00:~/.nx> ls -la
total 44
drwxr-xr-x 11 test0766 nxusers 4096 2007-08-13 15:30 .
drwxr-xr-x 20 test0766 nxusers 4096 2007-08-13 15:30 ..
drwxr-xr-x 2 test0766 nxusers 4096 2007-08-13 14:14 cache-gnome
drwxr-xr-x 2 test0766 nxusers 4096 2007-08-13 15:28 cache-kde
drwxr-xr-x 2 test0766 nxusers 4096 2007-08-13 15:30 cache-shadow
drwxr-xr-x 2 test0766 nxusers 4096 2007-08-13 15:29 cache-vnc
drwxr-xr-x 2 test0766 nxusers 4096 2007-08-13 15:28 cache-windows
drwx------ 2 test0766 nxusers 4096 2007-08-13 15:27 config
drwxr-xr-x 4 test0766 nxusers 4096 2007-08-13 14:14 C-test00-1183-A76C562ECFA489A...
drwx------ 2 test0766 nxusers 4096 2007-08-13 15:30 S-test00-1195-57280BC9AE8876C...
drwx------ 9 test0766 nxusers 4096 2007-08-13 15:30 temp
The client directory config contains all session configuration files of the user.
The files are stored in XML format and specify the host and port where connection
takes place, as well as the other settings selected by user at the time of session setup.
These XML files can also contain the password that will be used to connect to the remote server.
NX Client uses a simple scrambling algorithm to make this password illegible. However,
storing session passwords on clients is an inherently insecure operation and users are
discouraged from doing so.
When a session is running, you can find directories whose names have as format:
C-test00-1183-A76C562ECFA489AB35E5E305D527EE2F or S-test00-1195-57280BC9AE8876CAA773467719FC1027.
The first letter specifies if it is a NX server or NX client session. Contrarily to what normal
people could guess, C stands for server and S for client. The reason being that this name is similar
to the X (and TCP/IP) convention where Mozilla, the client running on NX (read application)
server, is connected to X server, running on NX client. What follows is the name of the NX server
running the session, the display number and a MD5 constituting the unique session ID.
The session directory contains all information needed by agents and libraries to run the session,
as for example the X authorization cookie needed by agent to connect to the X server. In case of
failures, you should check the session and errors files you find in the failed session's directory.
Failed sessions' directory have name prepended by F. session contains log output of agent and
NX libraries, clients file contains the output of X clients run by session. Logging of X clients
output can be disabled in the NX Node configuration file. errors is libXcomp specific and can
contain some warnings. Warnings are always harmless. They are often used by NX developers to have
suggestions on possible optimizations.
Session directories are automatically removed by NX server (at the end of session) and
the client (at next run), unless they have been instructed not to do so.
The last mention goes to cache directories. They are maintained by libXcomp library
to speed up session startup and compress the X traffic better, based on experience accumulated
in previous runs. Caches depend on the session type, so multiple cache directories can be present.
You can safely remove cache directories when you need space on your hard disk. This, of course,
will cause sessions to run slower until the new cache is populated.
