Setting up Ubuntu 12.04 LTS service

Let's talk about Ubuntu 12.04 LTS server setup. It is assumed that you are logged in as root.

• Add new user group and new user for your regular login
  groupadd admin
useradd -d /home/john -m -g admin john
  
• Delete this user password
  passwd -d john
• Set new password for this user
  passwd john
• Set bash as default shell for the user. Edit file /etc/passwd and set following line
  john:x:1000:1000::/home/john:/bin/bash
• Add this user (all admin group) to sudoers
  visudo
  Add line
  %admin ALL=(ALL) NOPASSWD: ALL
  NOPASSWD here means that when executin sudo system will not ask user password. It is important that this line was one of the last in the sudoers file.
• Disable root ssh login:
  vim /etc/ssh/sshd_config
  Find line PermitRootLogin and set it to no
  Now you’ll need to restart the sshd service:
  service sshd restart
• Disable user password login:
  vim /etc/ssh/sshd_config
  Add line
  PasswordAuthentication no
  Add lines:
  RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys
  Now you’ll need to restart the sshd service:
  service ssh restart
• Generate SSH keys for the user. Login as user john and execute following commands:
  ssh-keygen -t rsa
chmod 700 ~/.ssh
cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys
chmod 400 ~/.ssh/authorized_keys
• If using putty for ssh login onto Windows, you should reformat private key with puttygen (open puttygen, load private key, click 'Save private key') and then use this reformatted provate key for putty login

Download and install Oracle Server JRE7

Let's show how to download and install Oracle Server JRE7 from Oracle Download Site on our CentOS server.

First, you should go to download page Java SE Downloads, select JRE7 and accept license agreement. Then please check cookies that are set when you accept licence agreement. We need that cookie: gpw_e24. Just execute following command:

wget \
--no-check-certificate \
--no-cookies \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2Ftechnetwork%2Fjava%2Fjavase%2Fdownloads%2Fjre7-downloads-1880261.html" \
http://download.oracle.com/otn-pub/java/jdk/7u25-b15/jre-7u25-linux-x64.rpm
Then execute RPM:
sudo rpm -ivh jre-7u25-linux-x64.rpm

Setting up your CentOS Server

Well, now you've got your brand new server with CentOS installed on it. What are the first steps to establish server security? It is assumed that you are logged in as root.

• Add new user group and new user for your regular login
  groupadd admins
useradd john -gadmins
  
• Delete this user password
  passwd -d john
• Set new password for this user
  passwd john
• Add this user to sudoers
  visudo
  Find line
  root ALL=(ALL) ALL
  and add new line under this line
  john ALL=(ALL) ALL
• Disable root ssh login:
  vim /etc/ssh/sshd_config
  Find line PermitRootLogin and set it to no
  Now you’ll need to restart the sshd service:
  service sshd restart
• Disable user password login:
  vim /etc/ssh/sshd_config
  Add line
  PasswordAuthentication no
  Add lines:
  RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys
  Now you’ll need to restart the sshd service:
  service sshd restart
• Generate SSH keys for the user. Login as user john and execute following commands:
  ssh-keygen -t rsa
chmod 700 ~/.ssh
cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys
chmod 400 ~/.ssh/authorized_keys
• If using putty for ssh login onto Windows, you should reformat private key with puttygen (open puttygen, load private key, click 'Save private key') and then use this reformatted provate key for putty login

Crispy goes on

So, this is my another blog about software. Do I really have smth interesting to tell you? I think yes, I have. But, more importantly, I'll put here all my thoughts, experimentations and code snippets which can help you or me in the future. My previous blog was in Russian language. But this one will be in English. I want to tell with much more broad audience and English language gives me this chance.
What topics will be highlighted here? Well, mostly geeky ones: software engineering, hacks, languages like Java, Scala, Python, Javascript, R, bitcoins, machine learning, algorithms, data structures implementations, highload systems and more. I like all that and try to touch as much as I can.
Recently I was involved in following:

• making ad platform for mobile traffic
• refactoring very highload xml ppc aggragator
• making bitcoin arbitrage sfotware
• some machine learning exercises

I have a lot of boiling thoughts that rush out of me to be pusblished in this blog.
Let's begin then.