Web scraping, also called screen scraping, web data extraction or web harvesting is a technique to automatically harvest large amount of data from websites on the internet. The data is extracted and saved to a local file in your computer in a structured format. The target websites might block your IP address from doing so and this is a big hindrance when scraping a large amount of data from websites.
Web scraping is gaining a lot of popularity owing to the numerous applications it finds in all types of businesses, it requires a lot of analysis to set up the business model, revenue model, market research that can be done efficiently by gathering(scraping) data from competitors websites. Web scraping is an indispensable part of real estate industries, data augmentation, brand marketing, stock market trading and many other industries. As many as 40 million people around the world browse the internet anonymously according to a research from GlobalWebIndex.
Proxy servers play a role while web scraping because you need to be anonymous while gathering data from other websites. Proxy servers hide your identity by hiding your IP address and using an IP address of its own.
What is a proxy server?
A proxy server is an intermediate server between your ISP and the site that you are visiting. When you access a site with a proxy server, your request to access the site goes to the proxy server first before reaching the requested site. So a proxy server is working on your behalf to request the site access and also to give you the response from the website.
It is interesting to know that the target site will not know where the scraping request is coming from. To the site, it is just a web request from a server’s IP address ( proxy address that only you know). A good proxy server will send no information about the original machine which sent the request. The target site will not know because there is no difference between the two requests.
Why use Proxy Server for web scraping?
Two benefits of using proxies:
- Source machine’s IP address is not shown
- Getting past rate limits on the target site
The IP address of the machine being used for web scraping can be easily hidden with the use of a proxy. The target site will always see the IP address of the proxy server being used, hence the original machine is never exposed and can never be traced back.
The other benefit of using proxy servers is that you can get past rate limits on your target site. The website from where you are scraping data might have the software installed that might detect if there is a large number of access requests from a single IP address. It detects such activities as automated access, scraping, or fuzzing. Eventually, you might be blocked and will not be able to place future requests for a certain period of time from that IP address. For scraping more than a hundred pages of content from a website, there are high chances that you cross the rate limits.
To handle such huge data, you can distribute requests to multiple proxy servers. In this case, the target website will see only a few requests coming from a particular IP address, and so it always stays in rate limit without hindering the scraping program.
Apart from helping in web scraping, proxy servers are also useful to overcome geographical IP restrictions. For example, if you do not have access to watch an Australian TV show from your home country, you can request access through a proxy server in Australia that has an Australian IP address to overcome the restrictions. By using an IP server of Australian origin, the target site sees it as a request from Australian IP address only.
How to attach a proxy server to your scraping project?
Adding multiple proxies to your ongoing scraping project, on an existing software involves two steps:
- Pass the web scraper’s request through the proxy server.
- Rotate the proxy server’s IP address properly between requests.
The first step depends on the library that you are using the web scraping software. In the python request library, it can be done as:
import requests
proxies = {‘http’: ‘http://user:[email protected]:3128/’}
requests.get(‘http://example.org’, proxies=proxies)
After building a proxy connection URL, consult your network request library documentation to see how the proxy information is to be passed so that each request is routed properly.
The second step can be a challenging one depending on the amount of parallel processing being done and the margin that you want to keep to prevent getting hit by a blocked error on the target site.
How many proxy servers are required?
This is a frequently asked question because ingesting more than a few hundred or thousand pages always brings you to the need of using a proxy server so that you don’t get blocked from using the target site.
To stay below the rate limit, it is wise to hit the target site a reasonable number of times; the number that looks normal and not a machine done task. Depending on the content of the site, a human user(not a machine) can make upto 5-10 requests per minute on the target site.
A human user does open multiple tabs in the browser making a lot of requests in a few seconds. But there is always a pause as they take time to view content before making more requests. With all this being done, 300-600 requests can be made per hour. To be safe, many users go with making 500 requests per hour from one IP address to avoid hitting the rate limits.
Target site’s rate limit can only be guessed. Some websites might have even lower limits to block the IP address from making requests.
To know how many proxy servers to use, divide the total throughput of your web scraper, i.e the number of requests made per hour by a threshold of 500 requests per IP per hour to approximate the number of different IP addresses you’ll need.
For example, if you can ingest 100,000 URLs per hour, 100,000/500; which is 200; is the number of different proxy IP addresses you need to stay unblocked from your target website.
Choosing the Right Proxy Server
You might have to use hundreds of proxy servers and administering them might not be tenable.
Web scraping involves changing the pool of IP addresses, which requires setting up new pools of servers every now and then. There are a number of proxy servers available these days. It is better to rent or buy a proxy service and use its infrastructure instead of taking up the hassle of building your own server.
To decide which proxy server to use, consider the following two things:
- Is there a requirement for exclusive server access; i.e., Use of dedicated or shared server?
- Which protocol do you want to connect to the proxy server? SOCKS5 or HTTPS?
Paying for a premium proxy server gives you dedicated access. The main advantage of using a dedicated proxy server is that no one else will be interfering in your rate limit calculations. No one else will make requests along with you to the same target website through the same IP address.
With the prominence of proxy servers and websites to scrape content from, the possibilities are low that someone else will be scraping the same site at the same time through the same proxy IP address.
The second thing to consider; how to connect to proxy servers; through SOCKS5 or HTTPS? Most proxy servers offer both connection types and hence is not a problem while connecting a proxy server to your web scraping project.
Using a proxy server is definitely an integral part for anonymous web scraping. If you are web scraping, always be respectful to the websites you scrape. Use of proxies to remain anonymous is like a boon to avoid getting your IP address blocked by web servers, but should be used wisely.
Guest article written by: Rachael Chapman: A Complete gamer and a Tech Geek. Brings out all her thoughts and love in writing blogs on IoT, software, technology, etc. Website Link: https://limeproxies.com(Proxy Server) LinkedIn: https://www.linkedin.com/in/rachael-chapman-389b49169/
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