Proxy — Network & Internet Access

Proxy Network – Basics Guide

This guide explains what a proxy network is, why it is used, and how to use it, starting from the very basics.
It is intended for students, developers, and anyone working in institutional or server environments.

1. What Is a Proxy?¶

A proxy is an intermediate server between your computer and the internet.

Normal Internet Connection¶


Your Computer → Website

Internet Connection Using a Proxy¶

Your Computer → Proxy Server → Website

Instead of connecting directly to a website, your request is first sent to the proxy server, which then communicates with the website on your behalf.

2. What Is a Proxy Network?¶

A proxy network is a setup where: - Multiple users access the internet - Through one or more proxy servers

The proxy server: - Receives requests from users
- Forwards them to the internet
- Receives responses
- Sends the responses back to users

Proxy networks are commonly used in companies, universities, data centers, and HPC clusters.

3. Why Use a Proxy?¶

Common reasons include:

1. Internet Access Control¶

Restrict or allow access to specific websites
Widely used in offices, colleges, and research labs

2. Security¶

Hides the user’s real IP address
Protects internal networks from direct exposure

3. Monitoring¶

Allows administrators to monitor internet usage

4. Caching¶

Frequently accessed content loads faster
Reduces bandwidth usage

4. Types of Proxies (Basic)¶

HTTP Proxy¶

Used for standard web traffic
Example: browsing normal websites

HTTPS Proxy¶

Used for encrypted web traffic
Required for secure websites

5. How a Proxy Works (Step by Step)¶

You request a website
The request goes to the proxy server
The proxy checks access permissions
The proxy forwards the request to the website
The website responds to the proxy
The proxy sends the response back to you

6. Using a Proxy on Linux / macOS¶

Most command-line tools read proxy settings from environment variables.

Common variables: - http_proxy - https_proxy

7. What Does `export` Mean?¶

In Linux/macOS: - export sets an environment variable - Makes it available to all programs started from that terminal session

8. Setting Proxy Using `export`¶

Example Commands¶

export http_proxy="http://username:password@proxy_ip:port/"
export https_proxy="https://username:password@proxy_ip:port/"

Real Example¶

export http_proxy="http://application_user:Abc%60123456@100.100.100.100:100/"
export https_proxy="https://application_user:Abc%60123456@100.100.100.100:100/"

9. Breaking Down the Proxy URL¶

http://application_user:Abc%60123456@100.100.100.100:100/

Part	Meaning
`http://`	Proxy protocol
`application_user`	Proxy username
`Abc%60123456`	Proxy password (URL-encoded)
`100.100.100.100`	Proxy server IP
`100`	Proxy port

Note on URL Encoding¶

%40 is URL encoding for @
Password Abc@123456 becomes Abc%60123456

10. What Happens After Exporting the Proxy?¶

Once exported:

Tools like curl, wget, pip, apt, and git
Automatically route traffic through the proxy

Example¶

curl google.com
pip install numpy

11. Temporary vs Permanent Proxy Settings¶

Temporary¶

Works only for the current terminal session
Lost after closing the terminal

Permanent¶

Add the export commands to:

~/.bashrc
~/.profile

12. Security Warning ⚠️¶

Proxy credentials are stored in plain text.

Recommendations:

Avoid sharing terminal screenshots
Clear shell history if required
Use secure credential management when possible

13. Installing Python Libraries Using `pip` Through a Proxy¶

Method 1: Proxy in the `pip install` Command (One-Time)¶

pip install pandas --proxy http://application_user:Abc%60123456@100.100.100.100:100

✅ Uses the proxy only for this command.

Method 2: Export Proxy Once (Recommended)¶

Step 1: Export Proxy¶

export http_proxy="http://application_user:Abc%60123456@100.100.100.100:100/"
export https_proxy="https://application_user:Abc%60123456@100.100.100.100:100/"

Step 2: Install Package¶

pip install pandas

✅ pip automatically uses the proxy.

Method 3: Permanent Proxy for `pip` (Best for Servers / HPC)¶

Step 1: Create Config Directory¶

mkdir -p ~/.pip

Step 2: Create Config File¶

nano ~/.pip/pip.conf

Step 3: Add Configuration¶

[global]
proxy = http://application_user:Abc%60123456@100.100.100.100:100

Step 4: Install Normally¶

pip install pandas

14. Common Mistakes ❌¶

Wrong Package Name¶

pip install pands   # ❌
pip install pandas  # ✅

Missing URL Encoding¶

Use Abc%60123456
Not Abc@123456

15. How to Verify Proxy Is Working¶

pip install numpy -v

If you see:

Connecting to 100.100.100.100:100

➡️ The proxy is being used.

16. SSL / Certificate Errors¶

Try:

pip install pandas \
  --proxy http://application_user:Abc%60123456@100.100.100.100:100 \
  --trusted-host pypi.org \
  --trusted-host files.pythonhosted.org

17. Quick Summary 🧠¶

Method	When to Use
`--proxy`	One-time install
`export`	Session-wide usage
`pip.conf`	Permanent server setup

In short: A proxy is a middleman between you and the internet. Proxy networks are widely used in institutions for security, control, and performance.

```