You can change the port that your SSH server runs other than the default 22 by specifying the desired port number in your SSH server configuration file.

Set the Port option in /etc/ssh/sshd_config to your desired port as in the following example;

Port 22

You can use any number between 1 to 65535 as long as it’s not used by other programs.

Be sure to reboot your SSH server afterwards.

Smart Pricing is Google’s attempt to protect advertisers through their Google AdWords program which will automatically lower the CPC (Cost per Click) of an AdSense ad if Google think the publisher gives low conversion rate for the Google AdWords advertisers. This means that if an AdWords advertiser bids $1 on a keyword, you as an AdSense publisher might get a lot less than that $1 per click.

If you think you are earning too little per clicks, you might be smart-priced too. You may want to review the following suggestions to fix this situation.

One way to measure the success of a website is to know how much website traffic it receives. Traffic or visitors doesn’t just flock a website once it’s launched out of nowhere, so some effort need to be poured to get the traffic you want.

Increasing website traffic requires quite a bit hard work, and it is a continuous process. It might be slow at first, but once it reach its tipping point, things will work automatically as the job is carried out by the visitors, voluntarily. All you need to do at that time is to monitor and promote the process.

SSH comes with 2 applications for remote file transfer, namely scp and sftp. You can also use SSH to secure your rsync session.

The easiest of these are scp. The command is quite similar to cp in copying local files except that you’ll have to specify the remote user and host in your command. For example,

scp myfile.txt [email protected]:/remote/folder/

will copy myfile.txt from your local folder to /remote/folder in 192.168.1.10. remoteuser need to exist and have write permission to /remote/folder/ in the remote system.

sftp in the other hand works almost exactly like ftp but with secure connection. Most of the commands are similar and can be used interchangeably. The following sftp example will work exactly as ftp would.

$ sftp [email protected]
Connected to 192.168.1.10.
sftp> dir
file1      file2  file3   
sftp> pwd
Remote working directory: /home/user
sftp> get file2
Fetching /home/user/file2 to file2
/home/user/file2                                                   100% 3740KB 747.9KB/s   00:05    
sftp> bye
$ 

You can also use ssh to secure your rsync session. To do this, use –rsh=ssh or -e “ssh” with your normal rsync commands. The following 2 commands will work exactly the same;

rsync -av --delete --rsh=ssh /path/to/source [email protected]:/remote/folder/
rsync -av --delete -e "ssh" /path/to/source [email protected]:/remote/folder/

SSH clients will automatically be disconnected from the server and prompt the below message after being idle or inactive for a while.

Read from remote host oseems.com: Connection reset by peer
Connection to oseems.com closed.

This is due to the SSH servers’ configuration (often by default) to avoid hanging sessions and free up resources.

If you have administrative access to the SSH servers, you can configure it so that it will not easily disconnect idle sessions. This could be achieved by setting the parameters for TCPKeepAlive, ClientAliveInterval, and ClientAliveCountMax as per the following;

TCPKeepAlive no 
ClientAliveInterval 30
ClientAliveCountMax 240

What it basically means is that the server will not send the TCP alive packet to check if the client’s connection is working, yet will still send the encrypted alive message every 30 seconds. It will only disconnect after at least 2 hours of inactivity.

The following is the full explanation for the options;

 TCPKeepAlive
         Specifies whether the system should send TCP keepalive messages to the other side.  If they are sent, death of the
         connection or crash of one of the machines will be properly noticed.  However, this means that connections will die
         if the route is down temporarily, and some people find it annoying.  On the other hand, if TCP keepalives are not
         sent, sessions may hang indefinitely on the server, leaving “ghost” users and consuming server resources.

         The default is “yes” (to send TCP keepalive messages), and the server will notice if the network goes down or the
         client host crashes.  This avoids infinitely hanging sessions.

         To disable TCP keepalive messages, the value should be set to “no”.

         This option was formerly called KeepAlive.

 ClientAliveCountMax
         Sets the number of client alive messages (see below) which may be sent without sshd(8) receiving any messages back
         from the client.  If this threshold is reached while client alive messages are being sent, sshd will disconnect the
         client, terminating the session.  It is important to note that the use of client alive messages is very different
         from TCPKeepAlive (below).  The client alive messages are sent through the encrypted channel and therefore will not
         be spoofable.  The TCP keepalive option enabled by TCPKeepAlive is spoofable.  The client alive mechanism is valu‐
         able when the client or server depend on knowing when a connection has become inactive.

         The default value is 3.  If ClientAliveInterval (see below) is set to 15, and ClientAliveCountMax is left at the
         default, unresponsive SSH clients will be disconnected after approximately 45 seconds.  This option applies to pro‐
         tocol version 2 only.

 ClientAliveInterval
         Sets a timeout interval in seconds after which if no data has been received from the client, sshd(8) will send a
         message through the encrypted channel to request a response from the client.  The default is 0, indicating that
         these messages will not be sent to the client.  This option applies to protocol version 2 only.

If you don’t have administrative access to the server, you can configure your SSH client to send the alive message to the server instead to achieve the same result. The key here is the ServerAliveInterval option for the SSH client.

You can do this by updating /etc/ssh/ssh_config (applying the setting to every user in the system) or in ~/.ssh/config (single user). Set the following option to have the client send the alive packet every 30 seconds to the server;

ServerAliveInterval 30

The other alternative is to manually set the ServerAliveInterval option every time you’re connecting to a server by using the -o ServerAliveInterval=<time-in-second> prefix as the following example;

$ ssh -o ServerAliveInterval=30 [email protected]

PDF or Portable Document Format the most used and probably the de-facto file format for document exchange. The format was created by Adobe Systems back in 1993 and Adobe Systems produces Adobe Acrobat to create and edit PDF files.

While being the most powerful tool for the purpose, Adobe Acrobat doesn’t currently run natively in Linux. One good alternative for Linux users is PDFEdit.

PDFEdit is the most complete PDFEditor for Linux. It’s QT based and the functions are accessible through theGUI based editor. The editing operations can also be scripted using the ECMAScript.

The program is installable in Ubuntu and Debian with the following command;

$ sudo apt-get install pdfedit

When launched, users can edit PDF files almost the same way as using any other desktop publishing application.

SSH in most system by default allow public key login. You can disable it with these simple steps if you somehow need to;

1. Set PubkeyAuthentication to no in /etc/ssh/sshd_config

   PubkeyAuthentication no

2. Reload or restart SSH

   How to restart SSH service

If both www and non www domain of your website (http://example.com and http://www.example.com) serve the same website, and you want people going to http://example.com to automatically be redirected to http://www.example.com, there’s a few way that you can do so with Apache

Mostly used for passwordless SSH login; there are a few methods to copy your SSH public key to the SSH server.

1. Use SSH‘s bundled command, ssh-copy-id

   $ ssh-copy-id user@host

   If you want to use other public key rather that then one in the default location,
   use the -i option as the following

   $ ssh-copy-id -i ~/.ssh/other_key.pub username@host

2. Manually append the content of your public key file (normally ~/.ssh/id_rsa.pub to the server’s ~/.ssh/authorized_keys
3. Using the following simple Bash script

   $ cat ~/.ssh/id_rsa.pub | ssh user@host 'cat >> ~/.ssh/authorized_keys