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Cryptography

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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Sysadmin because even developers need heroes!!!

Google Compute Engine scp Files on a Linux or Unix or Mac OS X

Scp command copies files between hosts on a network using ssh for data transfer. How do I use scp toefacilitate the remote file transfer using Google Compute Engine virtual machines on a Linux, OS X or Unix-like system?
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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 for OpenSSL versions 1.0.2a, 1.0.1m, 1.0.0r, and 0.9.8zf.? How do I verify that my Linux server has been fixed against the OpenSSL vulnerability?
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Howto Configure PFSense Site-to-Site IPSec VPN Tunnel For Remote Access

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 encrypted site-to-site network, allowing networks at multiple remote locations to be able to securely communicate using my PFSense located in my SOHO?
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How To Setup SSH Keys on a Linux / Unix System

I recently read that SSH keys provide a secure way of logging into a Linux and Unix-based server. How do I set up SSH keys on a Linux or Unix based systems? In SSH for Linux/Unix, how do I set up public key authentication?
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HowTo: Create a Self-Signed SSL Certificate on Nginx For CentOS / RHEL

I operate a small web site on Cloud server powered by CentOS Linux v6.4. I would like to encrypt my site’s information and create a more secure connection. How do I create a self-signed SSL certificate on Nginx for CentOS/Fedora or Red Hat Enterprise Linux based server?
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GPG Change Passphrase Secret Key Password Command

I know how to cange a passphrase for openssh using ssh-keygen command. How do I change a GPG encryption key’s passphrase on Linux or Unix like operating systems? How do I change the passphrase of the secret key using gpg?
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Debian / Ubuntu: Install Duplicity For Encrypted Backup In Cloud

My cloud based backup service provider has ssh access to the backup system. How do I install and configure duplicity software for remote backups in incremental and encrypted format on Debian or Ubuntu Linux based desktop / laptop / server?
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Nginx: SPDY SSL Installation and Configuration On a Debian / Ubuntu Linux

Google Chrome/Chromium, Firefox and Opera browser support SPDY networking protocol. It enables faster browsing on supported sites. SPDY is similar to HTTP, with particular goals to reduce web page load latency and improve web security. SPDY achieves reduced latency through compression, multiplexing, and prioritization. How do I enable nginx SPDY support running on Debian or Ubuntu Linux server?
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Linux / Unix: Generate A MD5 String

I need to generate a md5 hash for given string. It will be used by shell script to generate keys for remote web service or cryptographic application. How do I generate a md5 hash based on any input string under Linux or Unix like operating systems?
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