Tag: OpenSSH

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How To Install OpenSSH on Ubuntu 16.04 LTS

Install OpenSSH on Ubuntu 16

OpenSSH (OpenBSD Secure Shell) is a connectivity tool that enables remote login via the SSH protocol, hence eliminating eavesdropping, connection hijacking, and other attacks. It helps to secure all network communications by encrypting all network traffic over multiple authentication methods through a secured tunnel.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo’ to the commands to get root privileges. I will show you through the step by step installation OpenSSH on an Ubuntu 16.04 Xenial Xerus server.

Install OpenSSH on Ubuntu 16.04 LTS

Step 1. First make sure that all your system packages are up-to-date by running these following apt-get commands in the terminal.

sudo apt-get update
sudo apt-get upgrade

Step 2. Installing OpenSSH on Ubuntu 16.04.

Install it by running the following command in your terminal:

apt-get install openssh-server

Furthermore, you can install the OpenSSH client application using the following command:

apt-get install openssh-client

After that, you should have SSH service enabled in your system:

systemctl start sshd.service
systemctl enable sshd.service

Last step is to open up the ssh firewall port:

ufw allow ssh
ufw reload

Step 3. Advanced Configuration OpenSSH.

Now sometime we may want to change some settings (for example, the port, and root login permission) . This can be done by editing the configuration file via command:

nano /etc/ssh/sshd_config

The first thing you may want to do is to change the default SSH listening port. Open the file and locate the line that specifies the listening port:

Port 22

Change it to something else. For example to 2022:

Port 2022

Save the file and close it. Then restart the service for the changes to take effect:

systemctl restart sshd.service

Congratulation’s! You have successfully installed OpenSSH. Thanks for using this tutorial for installing OpenSSH on your Ubuntu 16.04 LTS. For additional help or useful information, we recommend you to check the official OpenSSH web site.

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How To Replacing OpenSSH With Dropbear on CentOS

Replacing OpenSSH With Dropbear on CentOS

Dropbear is a relatively small SSH server and client. It runs on a variety of POSIX-based platforms. Dropbear is open source software, distributed under a MIT-style license. Dropbear is particularly useful for “embedded”-type Linux (or other Unix) systems, such as wireless routers.

Features

  • A small memory footprint suitable for memory-constrained environments – Dropbear can compile to a 110kB statically linked binary with uClibc on x86 (only minimal options selected)
  • Dropbear server implements X11 forwarding, and authentication-agent forwarding for OpenSSH clients
  • Can run from inetd or standalone
  • Compatible with OpenSSH ~/.ssh/authorized_keys public key authentication
  • The server, client, keygen, and key converter can be compiled into a single binary (like busybox)
  • Features can easily be disabled when compiling to save space
  • Multi-hop mode uses SSH TCP forwarding to tunnel through multiple SSH hosts in a single command. dbclient user1@hop1,user2@hop2,destination

This article assumes you have at least basic knowledge of linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo’ to the commands to get root privileges. In this tutorial we will learn through the step by step replacing Dropbear SSH in CentOS server.

Replacing OpenSSH With Dropbear on CentOS

To install, first you must add the yum repository information corresponding to your CentOS/RHEL version to yum:

For CentOS 6.x use:

#wget http://dl.fedoraproject.org/pub/epel/6/i386/dropbear-0.58-1.el6.i686.rpm
#rpm -Uvh dropbear-0.58-1.el6.i686.rpm

For CentOS 5.x use:

#wget http://dl.fedoraproject.org/pub/epel/5/i386/dropbear-0.55-1.el5.i386.rpm
#rpm -Uvh dropbear-0.55-1.el5.i386.rpm

First we will just install dropbear using yum:

 #yum install dropbear

Now we just need to start up new SSH server:

 #nano /etc/init.d/dropbear

Edit port dropbear:

 #OPTIONS=" -p 222"

Add dropbear to startup and start the sever:

#chkconfig dropbear on
#service dropbear start

Next you can stop the current OpenSSH server:

 #yum remove openssh-server

Note: Make sure you check that it is indeed running and verify from another box before you logout your current session otherwise.

Congratulation’s! You have successfully installed Dropbear. Thanks for using this tutorial for installing Dropbear SSH in CentOS system.