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--- vlsi:computing_remote [15/04/2013 01:49]
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+++ vlsi:computing_remote [30/07/2013 21:23]
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 ====== Accessing computing resources remotely ======
-[ __[[vlsi:home|Home]]__ ]
+[ __[[vlsi:home|VLSI Home]]__ ]
 [ __[[vlsi:workbook|VLSI Design WorkBook]]__ ]
 [ __[[vlsi:computing_main#contents|Back to index]]__ ]
@@ Linea 25: / Linea 25: @@
 Once you have obtained a VLSI computing account, you are not required to physically
 work in front of a VLSI machine. As a matter of fact, you can always access your VLSI
-machine remotely using the [[http://en.wikipedia.org/wiki/Secure_Shell|Secure Shell (SSH)]]
+machine remotely using the **[[http://en.wikipedia.org/wiki/Secure_Shell|Secure Shell (SSH)]]**
 connection protocol and just work as you would be in front of it. For security issues,
 VLSI and INFN machines allow remote access only through <nowiki>SSH</nowiki>. Connections
@@ Linea 562: / Linea 562: @@
 **Tunnelling**
+Double-hop ssh tunnel (ssh on one machine, then on another)
+Situation: A and B are remote hosts. Local machine can SSH into A, but not B. B ONLY accepts SSH connections from A.
+one SSH from local to A that tunnels from a secondary local port (like 2121) to port 21 on B, and then you can SSH to localhost:2121 and login on B
+Un modo ad esempio e':
 <code>
-ssh
+ssh -l username -L 7777:eltXXX.to.infn.it:22 zoroastro.to.infn.it cat -
 </code>
+poi la shell rest ain hang, si apre un altro terminale e si mette
+<code>
+ssh -p 7777 username@localhost
+</code>
+e funziona!
+See also //[[http://picobit.wordpress.com/2009/04/26/linux-ssh-forwarding-tunneling-duble-ssh-using-the-console/]]//
@@ Linea 578: / Linea 603: @@
 <code>
 cd ~/.ssh
-ssh-keygen
+ssh-keygen [options]
 </code>
 generate a key
+generate a couple of keys, one public and one private with the ''ssh-keygen'' command
+which come with OpenSSH
+You will be prompted to specify a path (the default one ''~/.ssh/id_rsa'' works fine) and a **passphrase** (do not
+use an empty passphrase)
+<code>
+Generating public/private rsa key pair.
+Enter file in which to save the key (/home/username/.ssh/id_rsa): <hit Return to leave default or specify a different path>
+Enter passphrase (empty for no passphrase): <enter a passphrase or leave it empty>
+Enter same passphrase again: <confirm passphrase>
+The key fingerprint is:
+:f8:08:27:20:a1:82:d7:ad:ac:44:30:48:71:17:05 username@local.hostname
+</code>
+After keys has been succesfully generated you have to **copy the public key on the remote system**
+you want to connect to through <nowiki>SSH</nowiki>
+<code>
+ls ~/.ssh
+</code>
+you can use ''scp'' itself,
+<code>
+cd ~/.ssh
+scp id_rsa.pub username@remote.hostname:~/
+</code>
+login on the remote system,
+<code>
+ssh username@remote.hostname
+</code>
+move the ''id.rsa.pub'' as ''~/.ssh/authorized_keys''
+<code>
+mv ~/id.rsa.pub ~/.ssh/authorized_keys
+</code>
+E questo e' sufficiente, loggarsi e immettere il passphrase oppure nulla se non la si e'
+inserita.
 [[http://www.thegeekstuff.com/2008/06/perform-ssh-and-scp-without-entering-password-on-openssh/]]
+\\
+\\
+**Viewing images from the command line**
+If you need to view any image but you can only use the terminal,
+use the //Eye of GNOME// image viewer, which is the official image viewer
+for the GNOME Desktop environment and available on all Scientific Linux dictributions.
+Use the ''eog'' command,
+<code>
+which eog
+/usr/bin/eog
+</code>
+To open an image,
+<code>
+cd /path/to/image
+eog fileName.png
+</code>
+See also \\
+[[http://projects.gnome.org/eog/]]