Technology Insights

Authenticate Linux To Active Directory On Windows – Centrify Express

I was working with a coworker today to setup a new Redmine server running on top of Ubunut 12.04 and one of the steps we completed in the process was setting up LDAP authentication in Redmine. Setting up LDAP authentication in Redmine requires the server running Redmine to be joined to the Windows Active Directory domain so I needed a quick way to auth Linux on Active Directory. I have used Centrify in the past and remember it being really easy to setup authentication from any form of Linux to a Windows domain and again it did not disappoint. Follow the directions below to join a Linux server to Active Directory using Centrify.

Technology Insights

SSH Add Server To known_hosts Automatically

If you ever need to write a shell script that uses either SSH or SCP to unknown hosts then you will likely have run across the issue of adding the remote host/server to the known_hosts file when automating either of the two commands are called within the script. You can easily get around this either by modifying the client computers ssh_config file or by using the -o switch available for both SSH (Secure Shell) and SCP (Secure Copy). Below we show how to modify the ssh_config file as well as an example of using each with the -o switch.

Technology Errors

AWS SSH Key Login Failed Permission denied (publickey,gssapi-keyex,gssapi-with-mic)

Having trouble logging into an AWS instance using an SSH key? I was too and when I finally figured out what the issue was I was kicking myself. Recently I was called to assist figuring out information about a clients AWS deployment for a project where the original developers were no longer available or answering questions. Most of the instances that I initially worked on had no issues once I was able to obtain the correct SSH key pem file from Amazon. When the project was closing down I was asked to assist backing things up and it appeared the SSH key was failing for two of the instances which also happened to be the oldest two instances (2 years old). Below I describe the error I was seeing via SSH as well as the easy resolution to the problem.

Code Snippets

RightScale RightScript To Add SSH Users To Linux Nodes On Boot

The below code snippet was used to add SSH users to RackSpace cloud CentOS Linux nodes being used as application servers and managed via RightScale. The SSH users were required during a testing phase so they could look through logs and make modifications to specific configuration files, etc. There are three things that have to happen to create the SSH user, allow them to login, and provide them the necessary rights on the server to accomplish their tasks which include adding the user, modifying the sshd config to allow password logins, and update the sudoers file to enable sudo access for wheel group users.