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Large enterprises and nuclear laboratories aren't the only organizations that need an Internet access policy and a means of enforcing it. My household has an Internet access policy, and the technique I've used to enforce it is applicable to almost any organization. In our case, I'm not too concerned about outside security threats. more>> […]
Many problems in science and engineering are modeled through ordinary differential equations (ODEs). An ODE is an equation that contains a function of one independent variable and its derivatives. more>>
SSH is a Swiss Army knife and Hogwart's magic wand all rolled into one simple command-line tool. As often as we use it, we sometimes forget that even our encrypted friend can be secured more than it is by default. For a full list of options to turn on and off, simply type man sshd_config to read the man page for the configuration file. more>> […]
Whenever a server is accessible via the Internet, it's a safe bet that hackers will be trying to access it. Just look at the SSH logs for any server you use, and you'll surely find lots of "authentication failure" lines, originating from IPs that have nothing to do with you or your business. more>> […]
It sounds like a "back in my day" story, but I really do miss the days when laptops had LED activity lights for hard drives and Wi-Fi. Sure, some still have them, but for the most part, the latest trend is to have no way of knowing if your application is pegging the CPU at 100%, or if it just locked up. more>> […]
I love my latest Android device (see the March 2015 issue's Open-Source Classroom column for details), but for some reason, it won't automatically connect to my Bluetooth headset. When I turn on my headset, I want it to connect to my Android device so I can start using it right away. more>> […]
Nicolas Dichtel and Thierry Herbelot pointed out that the directories in the /proc filesystem used a linked list to identify their files. But, this would be slow when /proc directories started having lots of files, which, for example, might happen when the system needed lots of network sockets. more>> […]
On 19th March 2015, multiple high and moderate severity level vulnerabilities released in OpenSSL, a Secure Sockets Layer toolkit used in a Linux and Unix-like systems. How can I fix these vulnerabilities on a CentOS/RHEL/Ubuntu and Debian Linux based server? How do I verify that my Linux server has been fixed against the OpenSSL vulnerability?Read answer to […]
How can I mount remote directory with ssh on a Linux bases system? How do I use SSHFS to mount remote file systems over SSH on a Ubuntu or Debian/RHEL/CentOS/Arch Linux system?Read answer to: "How To Mount Remote Directory With SSHFS on a Linux"
I'm a new FreeBSD Unix system user. How can I find out the process/programs names listing on a certain port on a FreeBSD Unix systems using command line? How do I lookup the process which is currently bound to the given network port on a FreeBSD server?Read answer to: "FreeBSD Unix Find Out Which Programs Are Listing On a Given Port Number" […]
How can I modify partition labels on a Linux operating systems? How to change disk name on the ext4 file system on a Ubuntu Linux using command line?Read answer to: "Linux Change Disk Label Name on EXT2 / EXT3 / EXT4 File Systems"
My OpenSSH server listing on TCP port number 2222. How can I use ssh-copy-id with an sshd server with listing on a different port on a Linux or Unix-like systems?Read answer to: "Use ssh-copy-id with an OpenSSH Server Listening On a Different Port"
There are certain files in Ubuntu Linux (or Unix-like systems) that only root user access or edit. How can I edit and/or open files that requires admin (root) access on a Ubuntu Linux?Read answer to: "Ubuntu Linux: Edit and Open Files That Require Administrator Privileges"
I'm a new Ubuntu 12.04/14.04 server user. How do I install and use memcached on an Ubuntu Linux 14.04 LTS server? How can I my apps written in PHP or Python can use memcached on an Ubuntu LTS server?Read answer to: "Ubuntu Linux 12.04/14.04 LTS Install Memcached Server For Python and PHP Apps"
I work from a small office/home office and I need to set up an IPSec site-to-site VPN between a Cisco/OpeNBSD IPSec-enabled gateway and firewall running PFSense. How do I configure the VPN tunnel so that I can access remote subnet and servers behiend a Cisco firewall/router securely? How do I setup a tunnel mode configuration which will provide you with an e […]
I recently switched from MS-Windows server to a FreeBSD Unix server. How can I see list of mounted file systems on a FreeBSD based Unix server using command line options?Read answer to: "FreeBSD Unix Show Mounted File Systems"
I'm a new Ubuntu Linux user. In Linux, Apple OS X or Unix-like systems, how do I reissue or repeat a long command without retying it?Read answer to: "Bash: Reissue And Repeat A Long Command Without Retyping It on a Linux, OS X & Unix"