Crawler Agent Basics

When developing a crawler program, we often encounter website restrictions on frequent requests, and in order to circumvent such restrictions, we need to use a proxy server. Proxy servers can hide the real crawler IP address, thus reducing the risk of being blocked. A common proxy method is to constantly switch IPs to avoid blocking.

In Python, we can use the requests library for crawler programming, combined with proxy servers to realize IP switching. Here is a simple example code:

import requests

proxy = {
'http': 'http://1.2.3.4:8000',
'https': 'https://1.2.3.4:8000'
}

response = requests.get('https://www.example.com', proxies=proxy)
print(response.text)

IP Proxy Pool Setup

In order to realize automatic IP switching, we need to build an IP proxy pool. A proxy pool is a container that stores various proxy IPs from which we can randomly select IPs to send requests. Usually, we can use the services of a third-party proxy IP provider, or we can build our own proxy IP pool.

The method of building your own proxy IP pool generally involves crawling IP information from free proxy IP sites and filtering and verifying it. Below is a simple sample code for crawling IP addresses from proxy sites:

import requests
from bs4 import BeautifulSoup

def get_proxy_ip(): url = ''
url = 'https://www.free-proxy-list.net/'
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')
table = soup.find('table', id='proxylisttable')
rows = table.find_all('tr')[1:]
for row in rows: columns = row.find_all('tr')[1:])
columns = row.find_all('td')
ip = columns[0].text
port = columns[1].text
print(ip + ':' + port)

get_proxy_ip()

Tips for using IP Proxy

When using an IP proxy, you need to pay attention to some tips to improve the effectiveness of the proxy. First, update the proxy IP pool regularly to remove invalid IPs and add new available IPs. second, avoid switching IPs frequently as this may cause server anomalies. Also, be careful to set the request header of the proxy IP to make the request look more like a normal browser request.

In conclusion, IP proxy is a commonly used technique in crawler programming. Through the reasonable use of proxy IP pools, it can help crawler programs to circumvent the request limitations of websites and improve crawling efficiency.