C# Proxy IP Crawler Library: C# Support Proxy IP Crawler Library

Teach you to use C to get a proxy IP crawler!

Recently, a lot of partners are asking how to prevent the website from blocking the IP by writing a crawler in C. This is not difficult to say, but also not simple to say. Today, let's break it up and talk about how to use proxy IP to give your crawler a "vest", focusing on recommending our own!ipipgoThe service is definitely much more hassle-free than tossing it on your own.

Why do I need a proxy IP?

For example, the kiosk under your house sells a limited number of eggs every day. If you go to buy eggs by yourself repeatedly, the boss won't sell them to you, right? Proxy IP is like getting a different person to buy for you, so the boss won't recognize you. Especially for data collection, if you don't use a proxy IP, you will be blacklisted by the website in minutes.

How to play with proxy IP in C

Let's start with the most basic usage, hanging proxies when using HttpClient:

var handler = new HttpClientHandler
var handler = new HttpClientHandler
    Proxy = new WebProxy("121.36.210.212:8000"),
    UseProxy = true
}; var client = new HttpClientHandler { Proxy = new WebProxy("121.36.210.212:8000", UseProxy = true)
var client = new HttpClient(handler); // Remember to add the timeout setting.
// Remember to add the timeout setting
client.Timeout = TimeSpan.FromSeconds(30); var client = new HttpClient(handler); // Remember to add a timeout setting.

Note the use ofipipgoThe example IP, when you actually use it, you have to get the latest proxy from their API. A common mistake that newbies make is forgetting to set a timeout, and the program gets stuck there, a pit I've stepped over for you.

There is a way to manage the agent pool

It is not enough to use a single proxy, you have to create a proxy pool. It is recommended to useipipgo's Intelligent Proxy Pool Service, they automatically maintain the available proxies. You can refer to this structure if you write your own:

Practical case: e-commerce price monitoring

Last year, I helped a friend to do a certain e-commerce price comparison system, using theipipgoThe high stash of proxies + auto-switching function to successfully bypass anti-climbing. The core code looks like this:

// Get 10 proxies from ipipgo
var proxies = GetIpipgoProxies(10);

foreach(var url in targetUrls)
{
    var randomProxy = proxies[new Random().Next(proxies.Count)]; var randomProxy = proxies[new Random().
    try{
        // Random proxy access here
        var html = CrawlWithProxy(url, randomProxy);
        ParsePrice(html);
    }
    catch{
        MarkBadProxy(randomProxy); // mark the proxy as invalid
        proxies.Remove(randomProxy); }
    }
}

Frequently Asked Questions QA

Q: What should I do if I always get my IP blocked?
A: Three key points: 1) Useipipgoof high stash agents 2) Control the frequency of access 3) Regularly change the UserAgent

Q: How to solve the problem of slow agent speed?
A: RecommendedipipgoThe dynamic BGP line of their transit node can control the delay within 200ms. Remember to set a reasonable timeout in your own code, and don't wait.

Q: What if I need to deal with CAPTCHA?
A: In this case it is recommended to useExclusive IP packages from ipipgo, used in conjunction with a coding platform. The probability of encountering a CAPTCHA is much higher with a shared IP.

Guide to avoiding the pit

There are a few minefields that newbies tend to step into:

• I thought I was invisible when I used a transparent proxy (recognize high stash proxies)
• SSL certificate validation is not handled (ServicePointManager configuration has to be added to the code)
• Forget to set up connection pooling (don't use HttpClient in singleton mode)

Finally, to be honest, the cost of maintaining a proxy server by yourself is too high, and just the replacement maintenance after the IP is blocked can drive a person crazy. Leave the professional work to the professionals.ipipgoWe have tested the proxy service of our team, the average daily volume of ten million requests can be completely carried, there is a free trial quota, register an account to try to know.