Install Rsync and Lsync on CentOS, Fedora or Red Hat

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Have you ever needed to copy files from your local computer over to your web server? You may have previously used File Transfer Protocol (FTP) applications for this task, but FTP is prone to being insecure and can be challenging to work with over the command line. What if there was a better way? In this tutorial, we’ll be covering two popular utilities in the Linux world to securely assist in file transfers, rsync and lsyncd. We’ll show you how to install and use both in this article. Let’s dig in!

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Protecting against CVE-2018-14634 (Mutagen Astronomy)

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There is a new exploit, rated as 7.8 severity level,  that affects major Linux distributions of RedHat Enterprise Linux, Debian 8 and CentOS named Mutagen Astronomy. Mutagen Astronomy exploits an integer overflow vulnerability in the Linux kernel and supplies root access (admin privileges) to unauthorized users on the intended server. This exploit affects Linux kernel version dating back from July 2007 to July 2017.  Living in the kernel, the memory table can be manipulated to overflow using the create_tables_elf() function. After overwhelming the server, the hacker can then overtake the server with its malicious intents. Continue reading “Protecting against CVE-2018-14634 (Mutagen Astronomy)”

7 Extremely Useful Linux Commands for Beginners

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#1: ls : What’s in this directory?

The command ls stands for list directory contents. And, cleverly, it will do just that: list a directory’s contents! Using it with -F will give a list of the directories contents, and denote items that are other directories with a trailing /.

ls -F

On my server returns:

allthethings.txt important.doc Indominus/ Misc/ probs.xls Red Wings/ Spreadsheets/ Work/

In the above case, allthethings.txt, garbage.file, important.doc, and probs.xls are files, and Indominus, Misc, Red Wings, Spreadsheets, and Work, each with the trailing /, are directories!

There are many other options, or switches, such as -F that can be used with ls for improved results. For example:

ls -lFa

Returns:

dr-xr-x---. 10 root root 4096 Apr 17 12:01 .
drwxr-xr-x. 19 root root 4096 Apr 14 12:45 ..
-rw-r--r-- 1 root root 0 Apr 17 12:00 allthethings.txt
-rw------- 1 root root 483 Apr 14 12:45 .bash_history
-rw-r--r--. 1 root root 18 Dec 28 2013 .bash_logout
-rw-r--r--. 1 root root 176 Dec 28 2013 .bash_profile
-rw-r--r--. 1 root root 361 Jan 1 01:24 .bashrc
drwxr-xr-x 3 root root 4096 Jan 1 01:25 .cache/
drwxr-xr-x 3 root root 4096 Jan 1 01:25 .config/
-rw-r--r--. 1 root root 100 Dec 28 2013 .cshrc
-rw-r--r-- 1 root root 0 Apr 17 12:01 garbage.file
-rw-r--r-- 1 root root 0 Apr 17 11:58 important.doc
drwxr-xr-x 2 root root 4096 Apr 17 11:59 Indominus/
drwxr-xr-x 2 root root 4096 Apr 17 11:57 Misc/
-rw------- 1 root root 42 Apr 14 12:44 .my.cnf
-rw-r--r-- 1 root root 0 Apr 17 12:00 probs.xls
drwxr-xr-x 2 root root 4096 Apr 17 11:57 Red Wings/
-rw------- 1 root root 1024 Jan 1 01:22 .rnd
drwxr-xr-x 2 root root 4096 Apr 17 11:56 Spreadsheets/
drw------- 2 root root 4096 Apr 14 12:42 .ssh/
-rw-r--r--. 1 root root 129 Dec 28 2013 .tcshrc
drwxr-xr-x 2 root root 4096 Apr 17 11:57 Work/

In the above case two switches are added: -l and -a. The -l uses the long listing format, and the -a switch lists all of the files, including hidden files.

Each column contains an important bit of information:

Column | Information | Example

  • 1 | Permissions | drwxr-xr-x
  • 2 | # of Hard Links | 2
  • 3 | User That Owns File or Directory | root
  • 4 | Group for File or Directory | root
  • 5 | File Size | 4096
  • 6 | Timestamp | Apr 17 11:59
  • 7 | Filename | Indominus/

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How to Update the glibc (GNU libc) in CentOS / Red Hat

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Updating glibc on Red Hat Linux or CentOS Linux is a very simple process. Most commonly you will use the following command in the case of a security vulnerability, or perhaps just to verify that you’re running the most up-to-date library:

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chkconfig Command Examples for Red Hat and CentOS

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chkconfig is a command for checking and updating runlevel information for system services. For a primer on runlevels, check out our tutorial: Linux Runlevels Explained.

Pre-Flight Check
  • These instructions are intended specifically for checking and updating chkconfig.
  • I’ll be working from both a Liquid Web Core Managed CentOS 7 server, and I’ll be logged in as root.

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