SCP protocol

The SCP protocol is a network protocol, based on the BSD RCP protocol,^[1] which supports file transfers between hosts on a network. SCP uses Secure Shell (SSH) for data transfer and uses the same mechanisms for authentication, thereby ensuring the authenticity and confidentiality of the data in transit. A client can send (upload) files to a server, optionally including their basic attributes (permissions, timestamps). Clients can also request files or directories from a server (download). SCP runs over TCP port 22 by default. Like RCP, there is no RFC that defines the specifics of the protocol.

How it works

Normally, a client initiates an SSH connection to the remote host, and requests an SCP process to be started on the remote server. The remote SCP process can operate in one of two modes: source mode, which reads files (usually from disk) and sends them back to the client, or sink mode, which accepts the files sent by the client and writes them (usually to disk) on the remote host. For most SCP clients, source mode is generally triggered with the -f flag (from), while sink mode is triggered with -t (to).^[2] These flags are used internally and are not documented outside the SCP source code.

Remote to remote mode

In remote-to-remote secure copy, the SCP client opens an SSH connection to the source host and requests that it, in turn, open an SCP connection to the destination. (Remote-to-remote mode does not operate by opening two SCP connections and using the originating client as an intermediary). It is important to note that SCP cannot be used to remotely copy from the source to the destination when operating in password or keyboard-interactive authentication mode, as this would reveal the destination server’s authentication credentials to the source. It is, however, possible with key-based or GSSAPI methods that do not require user input.^[2]

Issues using talkative shell profiles

SCP does not expect text communicating with the ssh login shell. Text transmitted due to the ssh profile (e.g. echo “Welcome” in the .bashrc file) is intrepreted as an error message, and a null line (echo “”) causes scp to deadlock waiting for the error message to complete.^[2]

SCP program

The SCP program is a software tool implementing the SCP protocol as a service daemon or client. It is a program to perform secure copying. The SCP server program is typically the same program as the SCP client.

Perhaps the most widely used SCP program is the command line scp program, which is provided in most SSH implementations. The scp program is the secure analog of the rcp command. The scp program must be part of all SSH servers that want to provide SCP service, as scp functions as SCP server too.

Some SSH implementations provide the scp2 program, which uses the SFTP protocol instead of SCP, but provides the very same command line interface as scp. scp is then typically a symbolic link to scp2.

Typically, a syntax of scp program is like the syntax of cp:

Copying file to host:

scp SourceFile user@host:directory/TargetFile

Copying file from host:

scp user@host:directory/SourceFile TargetFile
scp -r user@host:directory/SourceFolder TargetFolder

Note that if the remote host uses a port other than the default of 22, it can be specified in the command. For example, copying a file from host:

scp -P 2222 user@host:directory/SourceFile TargetFile

As the SCP protocol implements file transfers only, GUI SCP clients are rare, as implementing it requires additional functionality (directory listing at least). For example, WinSCP defaults to the SFTP protocol. Even when operating in SCP mode, clients like WinSCP are typically not pure SCP clients, as they must use other means to implement the additional functionality (like the ls command). This in turn brings platform-dependency problems.

Fonte: en.wikipedia.org

In this tutorial I’ll walk you through setting up 3 Apache virtual hosts running on a single Ubuntu server. An Apache virtual host, as explained by Apache, refers to the practice of running more than one web site (such as www.company1.com and www.company2.com) on a single machine. Virtual hosts can be “IP-based” or “name-based”. By default, Ubuntu already has this capability enabled, so things are much easier to configure these days. Enough with the intro, this is how you do it:

LAST UPDATE:
 It's May 2014 and Ubuntu 14.04 has been out for a little while.
Navigate to /etc/apache2/sites-available and see what's there. 
In the past the default website file has just been named "default" while later it was "default.conf" yet now it is "000-default.conf."
 "sudo a2dissite 000-default.conf" disables the default web site, allowing you to promote another one in its place.

We are going to create 3 sites, site1.com, site2.com and site3.com

1. Create the folders that will host your new sites. By default, Apache in Ubuntu serves from /var/www. So create these:

mkdir /var/www/site1
mkdir /var/www/site2
mkdir /var/www/site3

2. Copy the current default setting found in /etc/apache2/sites-available/default and name it the same as your new site.

cp /etc/apache2/sites-available/default /etc/apache2/sites-available/site1
cp /etc/apache2/sites-available/default /etc/apache2/sites-available/site2
cp /etc/apache2/sites-available/default /etc/apache2/sites-available/site3

3. Edit the new config files for each site using your preferred text editor. Add the line ServerName server1 right below the ServerAdmin line and change both DocumentRoot and Directory to point to your new sites.
This is what it should look like (you’ll do exactly the same for each of your 3 new sites, repeat this step for as many new sites as you’ll be creating):

/etc/apache2/sites-available/site1

<VirtualHost *:80>
  ServerAdmin webmaster@localhost
  ServerName YOURDOMAIN.YOU
  DocumentRoot /var/www/YOURDOMAINFOLDER (without slash trail)
 <Directory />
  Options FollowSymLinks
  AllowOverride None
 </Directory>
 <Directory /var/www/YOURDOMAINFOLDER/> (WITH slash trail)
  Options Indexes MultiViews
  AllowOverride None
  Order allow,deny
  allow from all
 </Directory>
</VirtualHost>

4. After you have edited the config files for each of the 3 or how many virtual hosts you are creating, just tell Apache to start serving the new domains and stop serving the default:

sudo a2ensite site1
sudo a2ensite site2
sudo a2ensite site3
sudo a2dissite default

note: (a2ensite, a2dissite - enable or disable an apache2 site / virtual host)

5. Now reload apache and you should be able to get to each of your new domains:

sudo /etc/init.d/apache2 reload

6. At this point the virtual host setup is done, all that is left is to tell the server that our-test-site.local should be resloved to 127.0.0.1.
We do that by typing

sudo gedit /etc/hosts

and adding 127.0.0.1 our-test-site.local after the localhost (line 1).

The entire hosts file should look like

127.0.0.1   localhost
127.0.0.1   YOURDOMAIN.YOU
127.0.1.1   ubuntu-vm

7. Save it, close the editor and finally type

sudo /etc/init.d/apache2 restart

Pay attention… to the user’s permissions !!!

Il sistema operativo Linux offre molteplici strumenti per la gestione o la modifica dei file; in questo articolo mostrerò come utilizzare alcuni comandi per sostituire una o più parole all’interno di un file di testo.

Un comando piuttosto utile quando si deve sostituire una o più parole in alcuni file è questo:

sed -i ‘s/parola1/parola2/g’ *.txt

in questo modo la parola1 verrà sostituita dalla parola2 in tutti i file di testo presenti nella directory corrente.

Se però dovessimo eseguire questa sostituzione anche nei file presenti in alcune sotto cartelle allora il comando diventa:

find ./ -type f -exec sed -i ‘s/parola1/parola2/g’ {} \;

in questo caso ho fatto a meno del filtro per i file di tipo .txt e quindi verranno presi in considerazione tutti i file presenti nella directory corrente e nelle sue sottodirectory.

Con il comando find che è stata usata l’opzione “-exec”  che permette di eseguire un comando ogni volta che viene trovato un file che rispetta le regole impostate per la ricerca.

Nel caso precedente la ricerca comprende tutti gli elementi di tipo “file” ed esclude le directory.

Tutto quello che segue la direttiva “-exec” costituisce il comando da eseguire e i suoi parametri, fino al carattere “\;” che indica la fine della stringa di comando.

Un altro elemento fondamentale è il simbolo “{}” che indica il nome attuale del file trovato e che, in questo modo, essere usato come parametro dal comando che si vuole eseguire.

Nel comando precedente le parentesi graffe “{}” sono stati quotate e il carattere di fine comando è stato preceduto con uno slash “” per proteggere questi simboli dall’espansione della shell.

Il comando viene eseguito nella directory di partenza, quindi se il comando inserito prevede un output occorre tenerne conto.

Consiglio di cercare prima la parola, giusto per verificare cosa verrà trovato e sostituito:

find ./ -type f -exec grep -r “parola1” {} \;

Oppure si può usare il comando:

find ./ -type f -print0 | xargs -0 grep “parola1”

in questo modo verranno visualizzate tutte le righe che contengono la stringa indicata.

In particolare è stato usata la direttiva “-print0” che permette di avere come output il nome completo terminato da un carattere nullo. In questo modo la stringa prodotta può essere interpretata correttamente dal programma seguente.

Infatti l’output del comando find è connesso con un pipe al comando xargs il cui parametro “-0” indica che i nomi dei file ricevuti come input finiscono con un carattere nullo.

Il comando “xargs” si occupa di ricevere i nomi dei file ed eseguire il comando “grep”che a sua volta usa i parametri passati da xargs.

Se invece si vuole solo veder visualizzato il nome del file che la contiene, il comando è:

find ./ -type f -print0 | xargs -0 grep -l “parola1”

Il parametro “-l” indica che come output avremo la lista dei nomi dei file, ma non le linee, nelle sono state trovate le corrispondenze.

Faccio notare che in tutti i comandi elencati è stato ipotizzato che la ricerca avvenisse nella directory attuale e in tutte le sue sub-directory, ma se volessimo cercare in una cartella qualsiasi dovremo inserire il percorso ( relativo o assoluto):

find /home/user/ -type f | xargs grep -l “parola1”

Infine, se non fosse necessario usare dei parametri complessi per la ricerca dei file e si volesse solo ricercare ricorsivamente una parola o una frase all’interno dei file in più subdirectory, basta usare molto più semplicemente il comando grep con l’opzione “-r”:

grep “this text” *.php -r

In questo modo verrà cercata la stringa “this text” in tutti i file “.php” presenti nella directory attuale e in tutte le sue sotto directory.

In this post I’ll mention how to edit binary files using vi and the utility xxd that is a part of vi.

vi in hex mode

Use the xxd command by typing

:%!xxd

Edit hex data. Quit hex mode with

:%!xxd -r

Using xxd command

You can use the xxd command outside vi. If you have an existing binary file, you can convert it to hex

You can then edit the hex and convert it back to binary

One nice little thing that xxd does is to produce a C static array definition, very convenient for embedding resource files

xxd -i file.bin

Per estrarre i file .tar.gz
tar -xpvzf nomefile

Si ricordi i seguenti parametri per il comando
tar

• c: crea archivi
• x: li decomprime
• v: scorre la lista dei file, generalmente evitato nella (de)compressione in quanto potrebbe produrre un lungo output inutile
• z: comprime/decomprime in formato gzip
• j: comprime/decomprime in formato bzip2
• f: obligatorio per comprimere
• p: preserva i permessi

Specifichiamo quindi l’uso di tar per creare un archivio:
tar -cvzpf nome_archivio.tar.gz /percorso_directory_da_archiviare

Escludere file:

IMPORTANTE:
Nel caso in cui si aggiungano le cartelle da escludere, il percorso deve essere completo del ./ iniziale, NON deve essere presente il / finale.
Se non funziona, verificare di inserire la cartella da escludere SENZA ./ iniziale ne finale.

tar --exclude ./percorso/del/file_da_escludere -cvzpf nome_archivio.tar.gz ./percorso_directory_da_archiviare

Escludere determinate estensioni:
tar --exclude ‘*.estensione_da_escludere’ -cvzpf nome_archivio.tar.gz /percorso_directory_da_archiviare

Escludere determinate directory:
tar --exclude ./percorso/della/directory_da_escludere -cvzpf nome_archivio.tar.gz /percorso_directory_da_archiviare

P.S. ovviamente se i file e/o determinate estensioni e/o determinate directory dovessero essere molteplici, potrete utilizzare tutti gli --exclude che desiderate!

Per esempio:
tar --exclude ./_backup_db --exclude ./_backup_site --exclude ./civicrm_custom --exclude ./wp-admin --exclude ./wp-includes --exclude ./.git --exclude wp-content -cvzpf my-file-backup.tar.gz ./

Oppure possiamo racchiuderli tutti tra parentesi:
tar -cvzpf my-file-backup.tar.gz ./ --exclude={./_backup_db,./_backup_site,./.git,./wp-admin,./wp-content,./wp-includes}

Mi sarebbe tanto piaciuto intitolare l’articolo “Riparare i danni causati da Aruba”, ma alla fine ho deciso di non addossare la colpa a loro ma alle “intrusioni”, anche se probabilmente non è proprio così. Ma non voglio iniziare a criticare nessuno all’interno di questo post, mi sono già lamentato abbastanza nei giorni passati. Oggi voglio invece aiutare tutti i clienti Aruba, che come me, si sono ritrovati con il proprio sito Web infettato o ancora peggio ritenuto dannoso per gli internauti.

I passi da seguire per ripristinare il proprio portale sono pochi e molto semplici, applicabili da chiunque abbia un pò di praticità informatica. Le operazioni da eseguire sono:

• Eliminare il codice malevole dal proprio sito Web.
• Effettuare una scansione del proprio computer con un software antivirus.
• Richiedere una nuova analisi del proprio portale da parte di Google.
• Effettuare un cambio password del proprio account FTP.

Come primo punto è fondamentale iniziare a rimuovere il codice malevole dal proprio sito Web. Per fare ciò generalmente basta scaricare all’interno del proprio computer tutto il contenuto del proprio CMS caricato all’interno dello spazio Ftp e procedere ad una scansione Antivirus. Generalmente la stringa da eliminare è la seguente:

Se volete fare un lavoro pulito vi consiglio di installare nuovamente da capo il vostro sistema CMS. Effettuata questa prima operazione è importante effettuare una scansione del proprio computer, poichè molto probabilmente vi si sarà installato un malware che tenterà di intercettare i vostri dati di accesso Ftp, per poi successivamente infettare anche i vostri siti Web con lo stesso codice.

Vediamo adesso come richiedere una nuova analisi del proprio sito da parte di Google. Recatevi all’interno della sezione “Centro Webmaster Google” e, nel caso in cui non lo abbiate già fatto, procedete alla verifica dell’autore del vostro sito Web, operazione che vi permetterà di identificarvi come proprietario e di accedere alla funzione che in questo momento ci intaressa, ovvero “Diagnostica”.

Una volta entrati nella scheda della diagnostica procedete in “Malware” e dopodichè premete su “Richiedi nuova analisi da parte di Google”. Entro 24 ore Google passerà nuovamente a controllare il vostro sito Web e se ritenuto “pulito” verrà eliminato dalla lista dei siti Web considerati come pericolosi.

Da: Riparare ai danni causati dalle intrusioni Aruba – Luca Mercatanti.

There are many reasons why working on Linux has advantages, but for web developers, it should be a no-brainer, but just in case you really need reasons here are just a few of the main ones.
The main feature Linux boasts that makes it better suited for web development over any other Operating System is the fact your local apache server has the same setup as your live hosting. Even without this, the benefits of using Linux over Windows or Mac OS are massive. I’ll go through the main advantages with you in this article.

Spending less time worrying about problems

As Web Developers spend a lot of time on the Internet, whether its checking emails, working on twitter or downloading the latest patches for software you use. It’s nice to know your pc, and all the important work on it is save. When using Windows and even a Mac to an extent you can install Antivirus, anti-spyware and anti adware on your computer to have any chance of making sure its safe from the threats that come with using the internet these days. And even then, that is a lot of trust to be putting in the hands of a 3rd party company.

A real life, proper server to test on

When working on a site, many web developers work on a local development server before transferring it over to their live site. This enables them to test everything before it goes live. Any computer with a browser can view locally stored html files, although if you work with php in any form, you’ll need a server with php supported (guess what you can do that locally on the Linux box as well!).

Both Windows and Mac can be setup to run as a local server, although these have totally different setups from over 70% of all online servers, which run on Linux Machines.

When running Linux on your PC you can have a fully functioning web server on your computer with the exact same setup as your live site.
How to install Lamp on Ubuntu

Save Money

You don’t need to spend big bucks to have the latest and best Linux running on your computer. Licencing is non-existent as Linux is Open Source.You’ll be able to easily find a linux distro that will run on nearly any PC made within the last 10 years, possibly more if you really want to.

Instead of spending money on the applications you use, you can get something suitable for free, which can be installed in minutes without any hassle once you get past the relatively easy learning curve. And as Linux is open source it means that anyone who is interested can help out with the code, just like what happens with WordPress!

It’s Yours: Web Developers love Open Source Software

It’s a fact that a majority of our community love Open Source software. Most of US believe that software should not be under proprietary license. So why use a software which is not open source. Linux is open source and you are free to do anything with the code. Change it, rip it, sell it whatever you want to do with it. Just keep it open source. 🙂

5 great free Linux Web Development Applications

Gedit

Comes as default with most Linux distributions, is a great simple no frills text editor which its quite popular for coding. Has syntax and tab support.
jEdit

Another text editor, though more advanced. This truly is a programmers text editors.
KompoZer

Kompozer is a great free wysiwyg web editor. Another similar software is Amaya which is a great free Web editor started by the WC3.

Aptana

Offers a full web development environment producing html, css and JavaScript.

Despite what some people believe browsing on the web using Linux is the exact same (apart from being allot safer). You can use all the big browsers apart from Safari, and I’ll also point out that all the addons work as they should no matter what Operating system you are running.

Lamp (Linux, Apache, MySql & PHP )

One I’ve already mentioned: The package LAMP, an anagram of Linux, Apache, MySql and PHP provides a fully working server which is the same package 90% of all websites run on. Great for offline development too!

Note: I haven’t linked to the above few programmes a I recommend you download them with your system installer.

For a great sized list showing some brilliant Linux Applications head over to 101 Most Useful Open-Source Apps for Small Business.

Designing on Linux

Designing on Linux is also a lot better than what people seem to think. By default many distributions include the programme Gimp, which although not exactly as detailed as Photoshop, it defiantly does pack a punch.

Other programmes that are great for designing are:

Inkscape

An Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format.

OpenOffice Draw
From the OpenOffice package offers the ability to draw anything from a quick simple design to detailed complex designs

It’s also possible if you don’t want to use any of the great Linux alternatives  to get Photoshop working on Linux using Wine.

Photoshop CS2 on Linux with Wine

And if there is a Windows programme that you can find for Linux then you can more than likely get it installed on Linux using Wine (Free) or Crossover (from €37.00 ) though crossover is more aimed at playing Windows games on Linux.

As an alternative if you do have a reasonably fast PC with sufficient ram you could use a virtual machine  (VIRTUAL BOX) and have a couple of flavours of Windows on it (licensing is the issue here, but you are just testing) and then check if IE7 and 8 (and IE6 for about 20% of the web users) can access your site. More importantly you can then see how badly these will mangle your code and what fixes you have to make.

Linux is suitable for everyone

A common misconception is that you need to be a big tech person or geek to use Linux, although this is true with some distributions such as Arch Linux, with the dawn of new distro’s like Ubuntu, you can have a fully working Computer with a few clicks and 15 – 20 mins of your time.

You can even use Wubi: the Ubuntu installer to install Ubuntu with a single click from Windows.

Helpful Readings:

• Offical Ubuntu Installation Guide
• Dual Boot Windows 7 and Ubuntu 10.04 Lucid Lynx
• Ubuntu 10.04 Post-Install Guide: What to do and try after installing Lucid Lynx!
• Installing Apps in Ubuntu

Because of licensing issues, Ubuntu is unable to play MP3s out of the box. We’ll show you how to play MP3s and other restricted file formats in about four mouse clicks.

The philosophy behind Ubuntu is that software should be free and accessible to all. Whether MP3 and other file formats are free is unclear in many countries, so Ubuntu does not include software to read these file formats by default.

Fortunately, it does include a package that installs the most commonly used file formats all at once, including a Flash plugin for Firefox.

Note: These instructions are for Ubuntu 10.04. There are small differences for earlier versions of Ubuntu. Continue reading →

Ubuntu adopted the new version of the Grub boot manager in version 9.10, getting rid of the old problematic menu.lst. Today we look at how to change the boot menu options in Grub2.

Grub2 is a step forward in a lot of ways, and most of the annoying menu.lst issues from the past are gone. Still, if you’re not vigilant with removing old versions of the kernel, the boot list can still end up being longer than it needs to be. Continue reading →