The Geek Diary

Linux

How to log every shell command in Linux

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Question: How to redirect the shell command history to Syslog? There are several methods to do this. You can try with any one of the 3 methods below: Method 1 – via rsyslog service To use rsyslog for logging every shell command, just follow steps below: 1. Create a new rsyslog configuration file, and define […]

How To Configure Restricted Bash Shell in Linux

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Restricted bash shell can be invoked using below command: # bash -r The ‘/bin/rbash‘ represents the restricted bash shell and can be created by creating as a soft link to ‘/bin/bash’ as shown below: # ln -s /bin/bash /bin/rbash Once soft link for /bin/rbash is created, one can launch restricted bash shell using below command: […]

How to generate PGP keys using GPG on Linux

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How to generate PGP keys using GPG on Linux The GNU Privacy Guard application allows you to encrypt and decrypt information, create public and private encryption keys, and use or verify digital signatures. GPG is based on the use of a pair of keys, one public and one private (or “secret”). Data encrypted with one […]

How To Configure NIS (Network Information System) Master and Slave Servers in CentOS/RHEL

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The Network Information Service consists of a client-server directory service protocol for distributing system configuration data such as user and host names between computers. NIS enables you to create user accounts that can be shared across all systems on your network. The description of NIS daemons are given below: portmap/rpcbind: The foundation RPC daemon upon […]

How to Identify NIS Authenticated Users

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This post describes how to identify Network Information Service (NIS) authenticated users. 1. To obtain a complete list of all NIS users, run the ypcat passwd command For example: [root@nisserver ~]# ypcat passwd test2:x:504:504::/home/test2:/bin/bash user1:x:501:501::/home/user1:/bin/bash user2:x:502:502::/home/user2:/bin/bash user3:x:503:503::/home/user3:/bin/bash 2. To identify whether a specific user is a NIS user, run the ypmatch [username] passwd command. – […]

DNF Update Fails With Error “GPG check FAILED” – CentOS/RHEL 8

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The Problem DNF Update fails with the below error: 2018-06-22T14:31:22 DDEBUG Cleaning up. 2018-06-22T14:31:22 INFO The downloaded packages were saved in cache until the next successful transaction. 2018-06-22T14:31:22 INFO You can remove cached packages by executing ‘dnf clean packages’. 2018-06-22T14:31:22 SUBDEBUG Traceback (most recent call last): File “/usr/lib/python3.6/site-packages/dnf/cli/main.py”, line 64, in main return _main(base, args, […]

How To Disable Weak Cipher And Insecure HMAC Algorithms In SSH Services In CentOS/RHEL 8

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Question: How To Disable Weak Cipher And Insecure HMAC Algorithms in SSH services in CentOS/RHEL 8? In order to disable weak Ciphers and insecure HMAC algorithms in ssh services in CentOS/RHEL 8 please follow the instructions bellow: 1. Edit /etc/sysconfig/sshd and uncomment CRYPTO_POLICY line: Before: # CRYPTO_POLICY=[Original value] After: CRYPTO_POLICY=[New value] 2. Make sure correct […]