Python Web Crawling Tutorial: Building a Crawler from Scratch

Hands-On Web Crawling with Python

Recently, many friends asked how to use Python to engage in website data capture, especially when encountering anti-climbing mechanism is always ban IP. today we will talk about this matter, focusing on how to use the proxy IP this artifact to crack the problem. First of all, let's say a real case: last year, there is a price comparison site old man, he wrote the crawler always be the target site blocked IP, and then used the proxy IP service, data collection efficiency directly turned over 3 times.

Why do I need a proxy IP?

Let's take an example, you go to the supermarket to buy special eggs, if you always wear the same clothes to go, the security guards will sooner or later have to keep an eye on you. The web server is like that security guard.Proxy IPs are your dresser.. Using ipipgo's proxy service is the equivalent of changing into different clothes every time you visit, and the server won't even recognize you as the same person.

import requests

proxies = {
    'http': 'http://username:password@gateway.ipipgo.com:9020',
    'https': 'http://username:password@gateway.ipipgo.com:9020'
}

response = requests.get('https://target-site.com', proxies=proxies)

What are the doors to look for when choosing a proxy IP?

There are a variety of proxy IP services on the market, here to teach you a few to pick thehard indicator::

Three Steps to Build an Anti-Blocking Crawler

1. The infrastructure needs to be in place: Install the requests library and fake_useragent first, don't use the fixed User-Agent.

from fake_useragent import UserAgent

headers = {
    'User-Agent': UserAgent().random
}

2. Proxy IPs should be rotated: It is recommended to use ipipgo's dynamic session feature, which automatically changes IPs for each request.

3. Requests should be paced like a real person: Don't send requests like a jerk, randomly sleep for 1-3 seconds.

What do I do if I encounter backcrawling?

Many sites have added these defenses recently:

• Captcha blocking (using a proxy IP reduces the probability of triggering)
• Request frequency monitoring (ipipgo's IP pool is large enough to spread the request pressure)
• Fingerprint tracking (better with browser fingerprint camouflage)

A practical guide to avoiding the pit

The newbie's common mistakeThree Fatal Mistakes::

1. Rigor mortis an IP until blocked (should set up fail auto switching)
2. Ignore HTTPS proxy settings (both https and http should be configured)
3. Forgetting to handle exceptions (add try-except for peace of mind)

QA time

Q: What should I do if my proxy IP is slow?
A: Choose a service provider like ipipgo that has a dedicated channel, their BGP lines are much faster than public proxies

Q: How do I test if the proxy is valid?
A: Try with this detection interface: http://gateway.ipipgo.com/checkip

Q: Do free proxies work?
A: Don't! Free agents are like roadside snacks, there is no place to talk about eating bad food. Professional things or to ipipgo this kind of regular army!

One final rant, do data collection tobe particular about the degreeThe first thing you need to do is to make sure you don't paralyze your website. Using a good proxy IP is like mastering the light power, can go in and out is the real skill. ipipgo recently new users to send 5G traffic, used to practice just right, the specific package to the official website to take a look at know.