Technologist

Tech stuff about Cloud, DevOps, SysAdmin, Virtualization, SAN, Hardware, Scripting, Automation and Development

Browsing Posts tagged ssh

“Git is a free & open source, distributed version control system designed to handle everything from small to very large projects with speed and efficiency.” –http://git-scm.com/

In this guide I will walk you through setting up a Git server and accessing it from a Git client over SSH.

Git Server
I am using CentOS 5.3 as my server.
Hostname: gitserver.example.com
SSH Port: 22444 (As opposed to the default port 22, for increased security)

Install Git

yum install git

Create a folder where you will keep the repositories

mkdir /opt/git

Create a git user and change the owership and permissions of the previously created folder to the new user

useradd -c “Git Repository” git
chown git:git git:git /opt/git/
chmod 770 /opt/git

Create an empty project, I am calling my project ‘myproject’

mkdir /opt/git/myproject.git

Initialize the repository using –bare to only include objects at the server side

cd /opt/git/myproject.git
git –bare init

You are done with the Git server, let’s take a look at the client

Git Client
Install Git on your client.

Debian/Ubuntu:
sudo apt-get install git-core

Red Hat/Centos:
yum install git (I am using the rpmforge repo)

Now it’s time to version-control your project.

Create a new folder to put your code (unless it exists already)

mkdir /home/john/myproject

Now it is time to add your project to Git (locally):

cd /home/john/myproject
git init

Add all the files in the current directory to be source controlled:
git add *

Commit the changes:
git commit -m “Myproject first commit”

Tell the Git client where to find the server and remote repository

git remote add origin ssh://git@gitserver.example.com:22444/opt/git/myproject.git

Push your project to the server

If you have shared SSH keys:
git push origin master

OR If you dont have configured SSH keys:
git push ssh://git@gitserver.example.com:22444/opt/git/myproject.git master

Now your project is under Git source control


Pull/Clone project:

The below will download the project folder in the current folder:

git clone ssh://git@gitserver.example.com:22444/opt/git/myproject.git

When you make changes to your project, you need to tell Git about it and commit the changes:

cd /home/john/myproject
git add *
git status (Check status)
git commit -a -m “A comment describing the change”

Running on runlevel 5 is not a good idea for a server, I try to run servers on runlevel 3 with as minimal packages as needed. But sometimes you need a graphical application or a browser for some reason or another. You can use VNC to connect to the server and do it over SSH to make sure the communication is encrypted.

This guide is to enable VNC over SSH on a Linux Server. I will use CentOS 5.2 server for this guide.

I will allow only user john to be able to VNC/SSH to the server. Since I will be testing GUI based stuff, I will need a graphical environment installed. I do not need to run my server in graphical mode, but I need to have the proper packages installed.

1) Install the X Window System group

[root@server ~]# yum groupinstall “X Window System”

2) Install the vncserver

[root@server ~]# yum install vnc-server

3) As the user that will use VNC, create VNC password

[john@server ~]$ vncpasswd

4) Modify VNC configuration to allow X (/home/john/.vnc/xstartup)

 #!/bin/sh

# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
exec /etc/X11/xinit/xinitrc

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
twm &

5) Start the vncserver as the user who will have access, use a display number that you will remember, here I am using 2. Also use the following arguments to make sure it ONLY listens to the localhost.

[john@server ~]$ vncserver :2 -geometry 1024×768 -nolisten tcp -nohttpd -localhost

6) Check that the VNC service is only listening locally

[john@server ~]$ netstat -ntlp

tcp 0 0 127.0.0.1:5902 0.0.0.0:* LISTEN 7927/Xvnc

7) Ok, now lets connect using VNC over SSH
From a remote station you will start an SSH session and forward an arbitrary port(e.g. 5544) to the vnc server’s localhost address on port 5092. (It ends with 2 because you started the vnc server with :2)
That means that whenever you are on Server2 and you send packets to localhost on port 5544, those packets will be forwarded through the SSH tunnel to the vnc Server localhost on port 5902.

[alex@server2 ~]$ ssh -L5544:localhost:5902 john@server.example.com

8 ) Now on Server2 start a VNC client/viewer and on the server address, enter:

localhost:5544

9) Enjoy your secure VNC session!

VNC over SSH

VNC over SSH