C# Web Crawling: Proxy IP for .

How hard is it to crawl data these days? Try this proxy IP trick

Brothers engaged in web crawlers understand that now the site anti-climbing more and more ruthless. Yesterday can run the program, today will be blocked IP. This time we have to move out of our savior - proxy IP. especially with C to engage in the development of the use of good proxy IP can make your crawler live longer.

What's the deal with proxy IPs?

In a nutshell.go online with a vest. Change your IP address every time you request something so that the site thinks a different person is visiting. It's like if you go to the supermarket to buy cigarettes and change your clothes every day, the cashier won't recognize you as the same person.

There are two common types of agents on the market:

Practical C Proxy Configuration

Let's use ipipgo's proxy service as a demo. Their proxy has an advantage, you do not have to manually change the IP every time, the system will automatically switch.

// Example with HttpClient
var handler = new HttpClientHandler
var handler = new HttpClientHandler
    Proxy = new WebProxy("gateway.ipipgo.com:8000"), var var handler = new HttpClientHandler = new HttpClientHandler {
    UseProxy = true
}

var client = new HttpClient(handler); // Remember to add the timeout setting.
// Remember to add a timeout setting, don't wait for it to die!
client.Timeout = TimeSpan.FromSeconds(15); var client = new HttpClient(handler); // Remember to add a timeout setting.

It would be easier to use WebClient:

WebClient wc = new WebClient();
wc.Proxy = new WebProxy("http://username:password@gateway.ipipgo.com:8000");

A few tricks to avoid blocking

1. Don't pull wool over a sheep.: Don't visit the same page too often from the same IP
2. Random rest time: add a Thread.Sleep(random number of seconds) between requests
3. Disguise the browser header: randomly select the User-Agent each time.

Frequently Asked Pitfall Questions and Answers

Q: What should I do if the proxy suddenly fails?
A: This situation is eighty percent of the IP is blocked, it is recommended to use ipipgo's dynamic IP pool, they automatically change the IP do not have to worry about!

Q: What should I do if my agent is slow?
A: Choose a node that is geographically close, such as climbing domestic websites with ipipgo's East China node

Q: Do I need to maintain my own IP pool?
A: No need at all, ipipgo's API can get available IPs in real time, which saves a lot of work compared to tossing it yourself!

Why ipipgo?

Having tested a few proxy services, ipipgo has two masterpieces:
1. 国内有自建机房，能压到50ms以内
2. Intelligent routing system, automatically avoiding blocked IP segments
3. Provide ready-made C SDK, integration as little as three lines of code

Lastly, I would like to remind you that using a proxy is not a get-out-of-jail-free card. The key is to control the frequency of requests and do a good job of handling exceptions. If you encounter 429 error code, you should stop and don't fight with the website. Remember, the crawler that lives a long time is a good crawler!