Linux – Page 3 – POFTUT

Category: Linux


What Is OpenSSL Library?

OpenSSL is most popular open source cryptography library which provides a lot of tools, libraries, algorithms about cryptography. It is mostly known with Secure Socket Layers (SSL) and Transport Layer Security (TLS) protocols. Supported Encryption Algorithms Encryption is used to make given data unreadable by the intruders. It is mainly used for confidentiality. OpenSSL supports following algorithms. RSA DSA AES DES 3DES Supported Hash Algorithms Hashing is used to create...


What Is Linux PAM (Pluggable Authentication)

Authentication is important part of the operations systems like Linux. As Linux operating systems are multi user systems and runs a lot of services and complex scenarios they generally need robust and easy to implement complex scenarios authentication system. Linux Pluggable Authentication a.k.a. Linux PAM is very robust and dynamic authentication system. In this tutorial we will try to explain important aspects of Linux PAM. History In 1995 Open Software...


How To Solve ssh-copy-id “ERROR: failed to open ID file” Error

ssh provides secure access to the remote systems console or command line. All linux boxes uses ssh securely. There are a lot of steps to make things secure and easy while connecting and using ssh. ssh provides passwordless authentication with certificates. We can use ssh-copy-id to send our certificate to the remote system but what can we do if we get following error

Try ssh-copy-id Now we want to copy our ssh public...


How To Install and Use GPG Encrytion In Linux In Order To Encrypt and Decrypt Files and Folder?

Security is important part of the today’s IT operations. There are a lot of tools which provides some part of the secure operations. GNU Privacy Guard or simply GPG is a one of them. It provides encryption, decryption, digital signatures and signing. Install GPG To Ubuntu, Debian, Mint and Kali For deb or apt based distributions we can install GPG with the following command for gnupg package.

Install GPG To...


How to Add Ssh Keys with ssh-add In Linux?

SSH protocol provides different ways for authentication. Key based authentication is the most secure one. In order to use key based authentication we should store the key in a command place. SSH agents reads keys and uses for authentication with remote system. We can use ssh-add to store keys in a common path. Key Files Public and private keys are store in files according to their algorithm. ~/.ssh/identity  holds RSA version...


How To Recover Data with ddrescue Command?

ddrescue is a GNU provided data recovery tool.It can copy and recover file, directory or whole hard drive. The best part of the ddrescue is it can prevent or solve read errors. Install For Ubuntu, Debian, Kali and Mint We can install ddrescue tool for deb based distributions like below. ddrescue command is provided with package name gddrescue.

List Hard Drives Before rescuing or copying files and directories we...


Linux Ssh Tunneling or Port Forwarding Local and Remote Ports with Examples?

Ssh protocol secure remote connections which is shell or terminal based to the remote systems. Ssh protocol and tool provides more than that. We can use ssh to create tunnels over local and remote systems or connect remote system X server. In this tutorial we will look how to tunnel and port forward locally and remotely. Local Port Forwarding – Forward or Tunnel Local System Port To Remote System Port Local...


How To Save and Restore Iptables Rules Permanently In Ubuntu, CentOS, Fedora, Debian, Kali, Mint?

Iptables is standard and popular firewall provides by Linux distributions like Ubuntu, CentOS, Fedora, Debian etc. Iptables rules are managed in run time where a lot of rules are added, changed and remove. These changes are temporary changes where only running configuration is changed but do not saved temporarily. In this tutorial we will look how to save iptables rules permanently in Linux. Save Ipv4 Rules in Debian, Ubuntu, Mint, Kali...


How To Start, Stop and Enable, Disable Iptables or Ufw In Ubuntu, Debian, Kali, Mint

Ubuntu is popular Linux distribution used in different enterprise or personal IT environment. Security is important part of the today IT. We can use firewall services like iptables in order to tighten security of our Ubuntu system. In this tutorial we will look how to install, remove, enable, disable, start and stop Ubuntu iptables. This tutorial can be used for Kali, Debian, Mint distributions too. Ufw or Ubuntu Firewall Ubuntu rebranded...

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