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X, SSH, VNC n´ all this stuff. Jürgen Salm 2.4.2004 / updated 11.07.2007. Operating Modes: Plain X. *X Host. X server. X client (e.g. xterm). Fast You have to sit in front of the *X host. Operating Modes: Remote X. PC. *X Host. X client (e.g. xterm). X server. Flexible
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X, SSH, VNC n´ all this stuff ... Jürgen Salm 2.4.2004 / updated 11.07.2007
Operating Modes: Plain X *X Host X server X client (e.g. xterm) Fast You have to sit in front of the *X host Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Operating Modes: Remote X PC *X Host X client (e.g. xterm) X server • Flexible Speed depends on network performance • The data is sent plain over the network • All X clients are lost when the PC restarts Access control is done on host and not on user level Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Operating Modes: Remote X with SSH PC *X Host X client (e.g. xterm) X server SSH client SSH server • Flexible • The data is sent encrypted over the network • Speed depends on network performance All X clients are lost when the PC restarts Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Operating Modes: VNC PC *X Host X client (e.g. xterm) VNC viewer X server VNC server • Flexible • Lifespan of X clients is independent of PC Speed depends on network performance • The data is sent plain over the network Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Operating Modes: VNC with SSH PC *X Host X client (e.g. xterm) VNC viewer X server VNC server SSH client SSH server • Flexible • Lifespan of X clients is independent of PC • The data is sent encrypted over the network Speed depends on network performance Jürgen Salm, ICM N PG R D B 2, 02.04.2004
VNC with SSH: The details PC *X Host X client (e.g. xterm) -display 127.0.0.1:y.0 <y> X11 Display Number Port 6000 + X11 Display Number X server localhost:x <x> VNC Display Number VNC viewer VNC server Port 5900 + remote VNC Display Number Port 5900 + local VNC Display Number SSH client SSH server Port 22 Note: Local VNC Display Number and Remote VNC Display Number can differ Jürgen Salm, ICM N PG R D B 2, 02.04.2004
VNC with SSHWhat has to be configured in putty? A putty session that is to be used to establish a tunnel for VNC should have the following configurations set. • (O) Backspace Key (Terminal->Keyboard) • (O) Window size and color (Window->Appearance&Colours) • (R) Auto-login username (Connection) • (M) Preferred SSH protocol version (Connection->SSH) • (R) Allow agent forwarding (Connection->SSH->Auth) • (R) Enable X11 forwarding (Connection->SSH->Tunnels) • (M) Forwarded ports (Connection->SSH->Tunnels) (e.g. L5999:127.0.0.1:5999) (M=mandatory, R=recommended, O=optional) Note: The screenshots on the following pages are taken from an older version of putty, so YMMV Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 1/8 • Enter unix hostname and session name(be sure that SSH is selected) Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 2/8 • Set auto-login username Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 3/8 • Set preferred SSH protocol Note: Nowadays, “SSH2 only” is the recommended setting. Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 4/8 • Allow agent forwarding Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 5/8 • Enable X11 forwarding Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 6/8 • Enter port forwarding(First enter the fields, then press “Add”. The result is shown on the right side) Please remember to replace xx and yy by your local and remote display numbers Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 7/8 • Save the settings(after saving, the session name will occur in the list of saved sessions) Jürgen Salm, ICM N PG R D B 2, 02.04.2004
Putty Configuration 8/8 • When you change the settings of an existing session, be sure to load it before you change anything and save it afterwards before you open it. Otherwise the changes will be lost. Jürgen Salm, ICM N PG R D B 2, 02.04.2004
FAQ • What is the greatest disadvantage of VNC?VNC always works in „single window mode“. That means you will never be able to open an xterm as a separate Windows window. • What limits the usage of Xvnc?The number of Display (max. 99) and the available memory on the *X host. Jürgen Salm, ICM N PG R D B 2, 02.04.2004