\section{Using the Yohkoh Package from a Remote Node}
\index{remote login}

\subsection{Logging in from a remote node}

There are several ways to log into a remote node.  Here are a few of 
them. 
%
From Unix or DEC-Ultrix:
%
\ultrixinputa{telnet node\_name} 
\ultrixinputb{telnet isass0} 
\ultrixinputb{telnet node\_number} 
\ultrixinputb{telnet 192.68.162.109} 
\ultrixinputb{rlogin node} 
\ultrixinputb{rlogin isass2} 
\ultrixinputb{rlogin node -l username} 
\ultrixinputb{rlogin isass2 -l morrison}
%
From DEC-Ultrix:
\ultrixinputa{dlogin node} 
\ultrixinputb{dlogin 24707::} 
\ultrixinputb{dlogin 24.131}
%
From VMS:
\vmsinputa{set host node} 
\vmsinputb{set host 24707}
\vmsinputb{set host sag} 
%
When using TELNET, DLOGIN, and SET HOST you will be prompted for the
username and password of the account you want to log into.  For RLOGIN,
it will check the file .rhosts to see if the account and machine that 
you are logging in from should automatically log you into the remote
account.  A sample .rhost line is:

\begin{verbatim}
sxt1.space.lockheed.com         morrison        #  DECstation 5000
\end{verbatim}

\subsection{Redirecting X-Window Outputs}

If you have logged into a remote computer from a workstation, it is 
possible to redefine the machine that will display X-window output.  The
default for IDL is to make X-windows for plots and image displays.  Two
things have to be done before you can redirect the X-windows output: first
the output device needs to be defined to be the local node, and second
the security for the local node needs to be modified to give permission
for the remote node to create the window.

\subsubsection{Defining X-Window Output Node}
\index{window, remote login}
\index{X-window, remote login}
\index{DISPLAY, setting}

For Unix and DEC-Ultrix machines, a sample command would be:
%
\ultrixinputa{setenv DISPLAY sxt2:0} \index{setenv DISPLAY}
\ultrixinputb{setenv DISPLAY 192.68.162.109:0}
%
For DEC-Ultrix machines, it is possible to use DECNET protocol to create
the local X-window.  This is not recommeded since it is slow, but if it
is necessary, a sample command is:
%
\ultrixinputa{setenv DISPLAY sag::0} 
\ultrixinputb{setenv DISPLAY 24707::0}
%
For VMS machines, a sample command would be:
%
\vmsinputa{set display/create/super/node=sxt2} 
\vmsinputb{set display/create/super/node=sxt2/transport=tcpip}
%
It is possible to issue the ``setenv DISPLAY'' command from within IDL
by using the routine SETDISP (if the user forgets prior to starting IDL).
A sample call would be:
%
\idlinputd{setdisp, '192.68.162.109:0'}\index{SETDISP}

\subsubsection{Modifying Security to Accept Remote X-Windows}

For Unix machines, the following command will temporarily allow all remote 
nodes permission to create X-windows on your local machine.  The command on
the second and third lines will only allow access from the node sxt3.
%
\ultrixinputa{xhost +} 
\ultrixinputb{xhost +sxt3} 
\ultrixinputb{xhost +sxt3.space.lockheed.com}
%
It is possible to make a permanent change to the security list of nodes
which should be able to create X-windows on your local machine.  For the
DEC Ultrix or VMS machines using DEC Windows, the following steps are
required on the local machine:

\EEnumerate
\item Find the `Session Manager' window and make that the current window
\item Click and hold on the `Customize' item
\item Drag and select the `Security' item (by releasing the button)
\item Enter the remote host name.  An example would be `sxt2' (without
      the quotes) if sxt2 was defined in the /etc/hosts file.  If not,
      you would enter the full name `sxt2.spac.lockheed.com'
\item Click on `Add' and then `OK' to exit
\end{enumerate}
%
When trying to establish a connection between a DEC and a Sun machine, it
appears that it might be necessary to have the remote node name and number
located in the {\tt /etc/hosts} file.  If you have problems after following
the instructions above, you should try editing the {\tt /etc/hosts} file
and adding the remote host name.

On all Unix machines, the superuser can edit the file {\tt /etc/X0.hosts} and add the
names of the nodes which should be allowed access (one machine name per line).
