A proxy server is a device that usually sits between a client and the destination the user is trying to reach. It can provide security, anonymity, and even protection for the client behind the proxy. Here, we look at how to set up a web proxy, define access control lists, and troubleshoot it.

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Apache is a solid and stable web server that has been around for years. Apache can also be used to host multiple websites at a single time through the use of its virtual hosts feature. There is also an option to use SSL protocol, making websites safe and secure.

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The VNC server allows you to remote into the user’s system and view her desktop. With the end user’s desktop in view, you can more easily troubleshoot any issues she is having. Setting up a VNC serer isn’t hard at all.

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Secure your SSH connection is very important. I guess that you don’t want your password being hacked, right? There are some tips that can help you to have a securer connection. Here we go!

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Backup your Linux OS is the first thing I want to do after installing my Linux machine and necessary softwares. You can install your OS again but it takes long time and effort to install all the stuffs in your machine. Now I start to backup and restore my Ubuntu 9.10. It’s the same to the other distributions.

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Security Enhanced Linux (SELinux) is another layer of security for the Linux OS. Instead of turning it off, however, you could use SELinux in “permissive” mode, which allows everything to function normally but logs warnings when actions or commands would have been blocked. 

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There are a few different ways you can manage the password policies on you system.

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Network address translation (NAT) allows you to use a server as a gateway to a subnet, essentially controlling what goes in and out of your network. Suppose you have two network outside (192.168.1.0) and inside (172.168.1.0). You need to create a firewall rule to allow all your clients on the internal network to be able to communicate with the outside world.

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Understanding the basics of Linux security is the best method to keep your business from outside or inside attacks. 

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Kickstart server enables you to install Linux over the network via the HTTP, FTP, or NFS protocols. I choose to use the HTTP protocol here because it was the quickest to setup and slightly easier than the other two protocols. 

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Linux is truly just the kernel. Red Hat and the other distributions in existence today are software and configuration files packaged with the Linux kernel to bring you an entire operating system. The kernel can be used to load new drivers, support new hardware, or even offer a custom kernel for individual needs.

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Every time a program or command is run, a process is created for it. These processes are all unique and identified by the process identification (PID) that becomes allocated to it. Management of processes can help keep the system stable or help when the system becomes unstable. Here are some of the process management commands you use:

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The Lightweight Directory Access Protocol (LDAP) is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. This service allow you to store your users and passwords in a central location. Now, I will guide you how to setup network authentication with LDAP.

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Whenever something goes wrong – and sometimes when things go right – on the system, a message is generated by the syslog service. In all seriousness, understanding system logging is important so that you can troubleshoot when something goes wrong. 

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Group Collaboration is an essential part of any system administrator who deals with users. Knowing file and directory permissions will allow you to let users work together. Here, we look at three key features:

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In Red Hat, there are three different types of user accounts: root, normal user and system. The root account is the equivalent of the Administrator or Enterprise Admin account in the Windows world. You should never use this account because of the power of this account has. Ever!

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TeamViewer connects to any PC or server around the world within a few seconds. You can remote control your partner's PC as if you were sitting right in front of it. Now I will show you how to install the newest version of TeamViewer on Ubuntu.

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It’s common for system administrators to create their own repositories where they keep not only a copy of Red Hat (or CentOS) packages, but also their own custom software packages. Now I will guide you how to create a DVD repository from your CentOS DVD.

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A key skill for a system administrator is being able to deploy your own custom software. However, you first need to build an RPM package that contains your custom software. To build an RPM, you must do the following:

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In Red Hat, the popular package used for installation usually have the .rpm extension and can be installed through different means. Before starting to install the package, let’s take a look at the naming convention used by the system to describe packages.

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The key component to network troubleshooting is making sure that everything is working smoothly and that your network is functioning properly. There are quite a few commands that you can use when troubleshooting network problem.

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The benefit of this is that remote resources can be mounted automatically and without the need for the root user to perform the mount. This is done through the use of a special config file called maps. There are two key files to know when working with AutoFS:

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A disk quota is a limit set by a system administrator that restricts certain aspects of file system usage on modern operating systems. The function of using disk quotas is to allocate limited disk space in a reasonable way.

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Linux, like most operating systems, has a standard set of file permissions. Aside from there, it also has more refined set of permissions implemented through access control lists. Now we will find out how they are used to implement file system security for files, directories, and more.

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Linux Unified Key Setup, or LUKs, is a disk encryption for Linux. LUKs uses block device encryption, which protects the system when it is off (particularly if the drive is removed or stolen). If you are using this method, you are required to enter a password. You will be promoted for this password every time the system boots to decrypt the partitions for use by the system. So do not lose this password! If you do, anything you have encrypted will be completely inaccessible.

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I recently tried to convert CHM (Windows Help File) to PDF. There're many methods to achieve this. Now I give you an easiest way to make your PDF file from CHM using chm2pdf script.

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After setting up the layout of the different disks for the system. Now to be able to use these disks, we need to create a file system for each one, mount it somewhere on the file hierarchy, and set it so that it will always be available when the system boots up.

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Onion Proxy Server allows users of the Tor network to make anonymous outgoing connections via TCP. The key advantage that Tor has over other anonymity networks is its application independence and that it works at the TCP stream level. Tor is truly an amazing advance in anonymous communications across the Internet.

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The system uses swap space as type of “virtual memory” for when your physical memory begins to run low. It does this by using piece of disk storage to swap files in and out of memory (hence, the term swap). This capability can be useful on systems that don’t have large amounts of physical memory or when your system is running something that become more intensive.

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On any system it is important to manage the running services. Managing services enables you to ensure the stability and reliability that your system will offer. A service can range from something simple, such as providing your local system with the correct time, or something more complex, such as sharing a file system over the entire network for your users using NFS. 

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When the system boots up, it queries for the default runlevel, which is defined in the /etc/inittab file. When that default runlevel is located, the system boots into that particular runlevel. The different runlevels are essentially “states,” which allow services to be started or stopped depending on the runlevel you are in. 

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