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RHEL Howtos and Guides

Red Hat Enterprise Linux server tutorial for new and advanced users. Topic includes RHEL firewall, package management, Red Hat server security, various server configuration, mail-server, web-server, proxy-server, intrnet-server, file server and much more ( rss feed ).

Linux Check Disk Space Command

I recently switched from a Windows server to a Linux server operating system. I am using Ubuntu LTS server. How do I find out disk space utilization information using command line option?
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How To Patch and Protect Linux Kernel Zero Day Vulnerability CVE-2016-0728 [ 19/Jan/2016 ]

A very serious security problem has been found in the Linux kernel. A 0-day local privilege escalation vulnerability has existed since 2012. This bug affects millions of Android or Linux applications to escalate privileges. Any server or desktop (32 or 64 bit) with Linux Kernel version 3.8+ is vulnerable. How do I fix this problem?
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The OpenSSH project released an ssh client bug info that can leak private keys to malicious servers. A man-in-the-middle kind of attack identified and fixed in OpenSSH are dubbed CVE-2016-0777 and CVE-2016-0778. How do I fix OpenSSH's client vulnerability on a Linux or Unix-like operating system?
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How to list all iptables rules with line numbers on Linux

I recently added NAT rules on my RHEL 6.x system. How do I see the rules including line numbers that I just added in Linux?
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How to check boot path (partition) in Linux

How do I identify the boot device or boot path in Linux operating system?
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How to delete a single command from history on a Linux, OS X and Unix Bash shell

I'm working in Ubuntu bash terminal application and remotely on a RHEL server in cloud platform. I typed the wrong and dangerous command. I no longer wish to remember dangerous command in the history file. How can I remove or delete a single command from bash history file?
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How to backup and restore a partition table on Linux

Is it possible to just backup my Linux partition table and restore it when required? How do I restore partition table if it get deleted by mistake on Linux operating system? How do I backup and restore a GPT partition table on Linux?
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How to find out zone information for given country on Linux or Unix

How do I find out the current time for each zone name specified on the command line on a Linux, FreeBSD, OS X or Unix-like system? How do I report time zone information for Singapore or Japan on the command line?
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How To Read CPUID Instruction For Each CPU on Linux With x86info and cpuid Commands

Is there a CPU-Z like a freeware/open source software that detects the central processing unit (CPU) of a modern personal computer in Linux operating system? How can I get detailed information about the CPU(s) gathered from the CPUID instruction, including the exact model of CPU(s) on Linux operating system?
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How to find out AES-NI (Advanced Encryption) Enabled on Linux System

The Intel Advanced Encryption Standard (AES) or New Instructions (AES-NI) engine enables extremely fast hardware encryption and decryption for openssl, ssh, vpn, Linux/Unix/OSX full disk encryption and more. How do I check support for Intel or AMD AES-NI is loaded in my running Linux in my Linux based system including openssl?
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