Ubuntu Server as a VPN Gateway

 To connect multiple Ubuntu devices (clients) to one central Ubuntu server and share the connection securely over a VPN, here’s a detailed, step-by-step guide.

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Step 1: Set Up the Ubuntu Server as a VPN Gateway

This server will act as the central point, allowing other devices to connect to it.

1.1 Install OpenVPN on the Server

1. Log into your central Ubuntu server.
2. Update package lists:

   
   sudo apt update
   

3. Install OpenVPN:

   
   sudo apt install openvpn -y
   

1.2 Set Up Easy-RSA for Key and Certificate Management

OpenVPN requires certificates and keys for secure connections.

1. Install easy-rsa to help with certificate creation:

   
   sudo apt install easy-rsa -y
   

2. Create a new directory for the PKI (Public Key Infrastructure):

   
   make-cadir ~/openvpn-ca
   cd ~/openvpn-ca
   

3. Initialize the PKI:

   
   ./easyrsa init-pki
   

4. Build the CA (Certificate Authority) and follow the prompts:

   
   ./easyrsa build-ca
   

5. Generate the server certificate and key:

   
   ./easyrsa gen-req server nopass
   

6. Sign the server certificate:

   
   ./easyrsa sign-req server server
   

7. Generate Diffie-Hellman parameters:

   
   ./easyrsa gen-dh
   

8. Copy the keys and certificates to OpenVPN’s directory:

   
   sudo cp pki/ca.crt pki/private/server.key pki/issued/server.crt /etc/openvpn/
   sudo cp pki/dh.pem /etc/openvpn/dh2048.pem
   

1.3 Configure the OpenVPN Server

1. Create a configuration file for the server:

   
   sudo nano /etc/openvpn/server.conf
   

2. Paste the following configuration into server.conf:

   
   port 1194
   proto udp
   dev tun
   ca ca.crt
   cert server.crt
   key server.key
   dh dh2048.pem
   server 10.8.0.0 255.255.255.0
   ifconfig-pool-persist ipp.txt
   push "redirect-gateway def1 bypass-dhcp"
   push "dhcp-option DNS 8.8.8.8"
   keepalive 10 120
   cipher AES-256-CBC
   user nobody
   group nogroup
   persist-key
   persist-tun
   status openvpn-status.log
   verb 3
   

1.4 Enable IP Forwarding for Internet Sharing

1. Open /etc/sysctl.conf:

   
   sudo nano /etc/sysctl.conf
   

2. Find or add the line below to enable IP forwarding:

   
   net.ipv4.ip_forward = 1
   

3. Apply the change immediately:

   
   sudo sysctl -p
   

1.5 Set Up Firewall Rules for OpenVPN

1. Allow OpenVPN traffic through the firewall:

   
   sudo ufw allow 1194/udp
   

2. Enable NAT (Network Address Translation) to allow VPN clients to reach the internet through the server:

   
   sudo iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
   

   Replace eth0 with your server’s network interface if it differs.

1.6 Start and Enable the OpenVPN Service

1. Start the OpenVPN service:

   
   sudo systemctl start openvpn@server
   

2. Enable it to start at boot:

   
   sudo systemctl enable openvpn@server
   

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Step 2: Set Up VPN Clients (Each of the 10 Ubuntu Devices)

Each client needs its own certificate and configuration to connect securely to the VPN server.

2.1 Create a Certificate for Each Client

On the server:

1. Go back to the ~/openvpn-ca directory:

   
   cd ~/openvpn-ca
   

2. Generate a certificate and key for each client (e.g., client1, client2, etc.):

   
   ./easyrsa gen-req client1 nopass
   ./easyrsa sign-req client client1
   

3. Copy the client’s certificates and keys to a separate directory to transfer them:

   
   cp pki/ca.crt pki/issued/client1.crt pki/private/client1.key ~/client1
   

2.2 Create Client Configuration File

1. On the server, create a client configuration file for each client (e.g., client1.ovpn):

   
   nano ~/client1/client1.ovpn
   

2. Add this configuration, replacing your_server_ip with the server's public IP address:

   
   client
   dev tun
   proto udp
   remote your_server_ip 1194
   resolv-retry infinite
   nobind
   persist-key
   persist-tun
   remote-cert-tls server
   cipher AES-256-CBC
   verb 3
   
   <ca>
   # Paste contents of ca.crt here
   </ca>
   <cert>
   # Paste contents of client1.crt here
   </cert>
   <key>
   # Paste contents of client1.key here
   </key>
   

2.3 Install OpenVPN on Each Client Device

On each Ubuntu client:

1. Install OpenVPN:

   
   sudo apt update
   sudo apt install openvpn -y
   

2. Copy the client1.ovpn configuration file from the server to each client.

2.4 Connect Each Client to the VPN

On each client device, use the configuration file to connect:

sudo openvpn --config /path/to/client1.ovpn

To run this automatically on boot, copy the configuration to /etc/openvpn/client/ as client.conf and enable the OpenVPN service:

sudo cp /path/to/client1.ovpn /etc/openvpn/client.conf
sudo systemctl enable openvpn-client@client

---

Step 3: Testing and Sharing Data Across Clients

1. Verify VPN Connectivity: From each client, ping the VPN server to ensure the connection.

   
   ping 10.8.0.1
   

2. Enable File Sharing (Optional): Use SSH/SCP or set up an NFS shared folder on the VPN server to allow clients to access shared data.

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By following these steps, you will connect 10 Ubuntu devices through a VPN to a central Ubuntu server, securely sharing resources and internet access across the network.

Git Commands

 Initiate a repository:

# initialize an existing directory as a Git repository
$ git init

# retrieve an entire repository from a hosted location via URL
$ git clone [url]

 

Stage your files:

# Show modified files in working directory, staged for your next commit
git status


# Add a file as it looks now to your next commit (stage)
git add [file path]


# If you need to add ALL the modified files at once
git add .


# Unstage a file while retaining the changes in working directory
$ git reset [file]


# Difference of what is changed but not staged
$ git diff


# Difference of what is staged but not yet commited
$ git diff --staged


# Commit your staged content as a new commit snapshot
$ git commit -m "descriptive message"


# Add files and Commit your staged content as a new commit snapshot
$ git commit -a

 

Manage branch & merge:

# list your branches. a * will appear next to the currently active branch
$ git branch


# create a new branch at the current commit
$ git branch [branch-name]


# switch to another branch and check it out into your working directory
$ git checkout


# One line command to checkout a new branch
$ git checkout -b [branch-name]


# merge the specified branch’s history into the current one
$ git merge [branch]


# show all commits in the current branch’s history
$ git log


# Git branch rename
$ git branch -m <new_branch_name>


# Delete branch
$ git branch -d [branch name]

 

Inspect branch & compare

# Show the commit history for the currently active branch
$ git log


# Show the commits on branchA that are not on branchB
$ git log branchB..branchA


# Show the commits that changed file, even across renames
$ git log --follow [file]


# Show the diff of what is in branchA that is not in branchB
$ git diff branchB...branchA


# Show any object in Git in human-readable format
$ git show [SHA]
$ git show [commit]

# used to give tags to the specified commit.
$ git tag [commitID] 

 

Share & Update:

# add a git URL as an alias
$ git remote add [alias] [url]


# fetch down all the branches from that Git remote
$ git fetch [alias]


# merge a remote branch into your current branch to bring it up to date
$ git merge [alias]/[branch]


# Transmit local branch commits to the remote repository branch
$ git push [alias] [branch]


# Push commits to all branches in your repository
$ git push –all [variable name]


# fetch and merge any commits from the tracking remote branch
$ git pull

 

Tracking path changes

# delete the file from project and stage the removal for commit
$ git rm [file]


# change an existing file path and stage the move
$ git mv [existing-path] [new-path]


# show all commit logs with indication of any paths that moved TEMPO
$ git log --stat -M

 

Rewrite history

# apply any commits of current branch ahead of specified one
$ git rebase [branch]


# clear staging area, rewrite working tree from specified commit
$ git reset --hard [commit]

 

Temporary Commits

# Save modified and staged changes
$ git stash


# list stack-order of stashed file changes
$ git stash list


# write working from top of stash stack
$ git stash pop


# discard the changes from top of stash stack
$ git stash drop

 

 Ignoring patterns

# system wide ignore patern for all local repositories
$ git config --global core.excludesfile [file]

 

About Azure Boards

 What is Azure Boards:  

Azure Boards is a service within Azure DevOps that helps teams plan, track, and manage software development projects. Key features include: 

• Work Item Tracking: Manage user stories, tasks, and bugs. 

• Agile Tools: Supports Scrum and Kanban methodologies. 

• Boards and Backlogs: Visualize and manage tasks using Kanban boards. 

• Queries and Reporting: Create custom queries and track project progress. 

• CI/CD Integration: Links with Azure Repos and Pipelines for seamless workflows. 

• Customization: Tailor fields, workflows, and processes to fit team needs. 

• Collaboration: Enhance team communication with comments and notifications. 

Overall, Azure Boards improves project management and collaboration in software development. 

Azure Boards hubs:  

Azure Boards features several hubs that provide specific functionalities to help teams manage their projects effectively. Here’s a brief overview of each hub: 

• Work Items: Central hub for creating, viewing, and managing work items like user stories, tasks, bugs, and features. It allows users to track the status and details of each item. 

• Boards: Visual hub that displays work items in a Kanban board format. Teams can move items across columns to reflect their current status and progress. 

• Backlogs: A prioritized list of work items organized by iteration or area. It helps teams manage their product backlog and plan sprints effectively. 

• Sprints: Focused on managing and tracking work during specific time frames. Teams can view sprint progress, burndown charts, and allocate tasks for upcoming sprints. 

• Queries: A hub for creating and managing custom queries to filter and view work items based on specific criteria. It helps teams track work and generate reports. 

• Dashboards: Provides customizable dashboards that display key metrics and project insights through various widgets, helping teams monitor progress and performance at a glance. 

• Delivery Plans: Visualize and manage work items across teams and iterations, providing a timeline view of project delivery. 

These hubs collectively enhance project visibility, collaboration, and management, allowing teams to streamline their software development processes.