The post discusses how to build and push docker images on local docker system to the docker hub repository. For the purpose of this post, we will pull a CentOS image from the public Repository in Docker hub. Later we will run a container using this image and add a new file to the container. […]
Archives for November 2017
Error “530: permission denied” when user logs in to vsftpd server via ftp
The Problem Vsftp server is newly installed and has been brought up but can’t be accessed by certain users giving the error shown below. # service vsftpd status vsftpd (pid 5806) is running… # ftp localhost Connected to localhost.localdomain. 220 (vsFTPd 2.0.5) 530 Please login with USER and PASS. KERBEROS_V4 rejected as an authentication type […]
CentOS / RHEL : How to allow or deny Users to login to VSFTP Server
After installation and start of the VSFTPD service, two files are created in the /etc/vsftpd/ directory: “ftpusers” and “user_list“. These files are used to allow or deny login attempts. The behavior of ftpusers and user_list is configurable in the vsftpd.conf file using the userlist_deny option. The vsftpd.conf file also offers the option of adding a […]
How to Install and configure telnet in RHEL / CentOS 5,6
It is recommended to use ssh instead of telnet to connect to a remote system for security purposes. Passwords are transmitted in plain text when you use Telnet. If you still want to use telnet, follow the steps below. Install telnet 1. In order to turn Telnet on make sure that you have the correct […]
How to install Docker on Mac
Installing Docker on Mac is pretty straightforward. It has a Graphical installer .dmg file. The installation provides Docker Engine, Docker CLI client, Docker Compose, Docker Machine, and Kitematic. Pre-requisites for installing Docker on Mac 1. Docker requires OS X El Capitan 10.11 or newer macOS release running on a 2010 or newer Mac. 2. At […]
Understanding The /etc/sysconfig Directory
The /etc/sysconfig directory contains files that control the system configuration. See /usr/share/doc/initscripts*/sysconfig.txt for complete information about these files. The actual content of your /etc/sysconfig directory depends on the programs that you have installed on your machine. Some of the files found in the /etc/sysconfig directory are described as follows: atd: This file is used to […]
Linux Interview Questions : Open Files / Open File Descriptors
What is an open file? An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library, a stream or a network file. What is file descriptor? A file descriptor is a data structure used by a program to get a handle on […]
“yum history” command examples to display, rollback, redo, undo yum transactions
“yum history” feature of yum is a mostly overlooked but very powerful utility in Linux. It can be used to rollback/redo/undo yum transaction to a state where everything was working fine. yum history “yum history list” command when run without any arguments produces output similar to shown below. “yum history” or “yum history list” by […]
How to List / Start / Stop / Delete docker Containers
What is a Docker Container A running instance of an image is called a container. Docker launches them using the Docker images as read-only templates. If you start an image, you have a running container of this image. Naturally, you can have many running containers of the same image. We use the command “docker run” […]
How to List / Search / Pull docker images on Linux
What is a Docker Image Docker images are a read-only template which is a base foundation to create a container from. We need an image to start the container. Ther are a lot of pre-built images out there on the docker hub. You can also have your own custom image built with the help of […]