====== Miscellaneous about computing ======
===== TCP ports repartitions =====

  * Well-known ports (0 to 1023),
  * registered ports (1024 to 49151),
  * dynamic, private or ephemeral ports (49152 to 65535).

The //Epeios// related software uses ports 53700 to 53799.

  * //xdhqxdh//, for both incoming (//FaaS//) connections **from** the //Atlas// toolkit, and outgoing connections **to** to the //Atlas// toolkit: ''53700'', 
  * //xdhwebq//: (incoming, from ''xdhq.php'' script): ''53710'',



===== Sharing 'Linux' folder to 'Windows' =====

http://www.howtogeek.com/176471/how-to-share-files-between-windows-and-linux/

==== Under 'Linux' ====


  * Install //samba//,
  * ''smbpasswd -a <username>'' (''<username>'' seems to need to be an existing login, despite what can be found in some documentation),
  * add following section in ''/etc/samba/smb.conf'' :
<code>
[<name>]
path = /home/<user_name>/<folder>
available = yes
valid users = <username>
read only = no
browsable = yes
public = yes
writable = yes
</code>
  * relaunch //samba// (''service smbd restart'').

==== Under 'Windows' ====

In the file explorer, type ''\\<host>\<name>'' (''<name>'' is the same name as the one given in the above section.

===== 'ssh' on same server but different OSes =====

When you try to connect with //ssh// on a machine with more then one OS (a tablet which can be boot under //Windows// or //Android//, for example), //ssh// will complain, or even forbid the connection when you switch the target machine from one OS to another.

One solution is to share the same key between both OSes.

The other solution is to connect to one OS, then comment out the concerned line in the ''known_hosts'' file, the connect to the other OS, and finally uncomment the previously commented line in ''known_hosts''. You can no connect to the 2 OS and //ssh// will no more complain.

===== nmap =====

To scan local network : ''nmap -sP 192.168.0.1/24'' (''ip a'' for local address).

===== Dimensions of a SVG element=====

Function returning an array containing the x and y coordinate of the top left corner, the width and the height of the drawing area of a SVG of id ''id''. 

<code javascript>
function svgViewBox( id ) {
 let x = 0;
 let y = 0;
 let width = 0;
 let height = 0;
 let svg = document.getElementById(id);
 let viewBox = svg.viewBox.baseVal;

 if ( viewBox !== null ) {
  x = viewBox.x;
  y = viewBox.y;
  width = viewBox.width;
  height = viewBox.height;
}

 if ( height === 0 ) {
  if ( width !== 0 )
   return "";
 } else if ( width === 0 ) 
  return ""

 if ( width === 0 ) {
  x = 0;
  y = 0;
  width = svg.width.baseVal.value;         
  height = svg.height.baseVal.value;         
 }

  return [x.toString(), y.toString(), width.toString(), height.toString()];
}

</code>