Free proxy capture tool development practice (with source code)

First, why do you want to toss your own proxy capture tool?

Crawlers engaged in the network of friends understand that the free proxy IP and roadside stalls like sausages - smell good but easy to run thin. The ready-made proxy pool on the market either fails quickly or hides a charge trap. Last week, an e-commerce data collection brother to find me complaining, with a free proxy to access the target site eight out of ten times triggered the CAPTCHA, so angry that he almost smashed the keyboard.

The most tangible benefit of developing your own crawler is thatFull control of agent qualityIt's a good idea to keep an eye on the whole process from sowing to picking. Like home-grown vegetables, from sowing to picking the whole process to keep an eye on, always more than the supermarket to buy a number. Especially for long-term data monitoring projects, there are a set of stable agents in hand, much more reliable than temporarily looking around for resources.

II. Three axes of tool development

It's not hard to get into this stuff. You just have to grasp the three core things:

1. Choice of source:

Don't stick to the public proxy sites, try cold forum posts, tech blog comment sections, or even the issues section of GitHub could be hiding good stuff. Remember to use xpath and regular with digging, like taking a shovel and sieve to pan for gold.

2. The validation mechanism should be sufficiently robust:

Don't be silly only to detect port 80, at least three passes: HTTP/HTTPS dual-protocol detection, response time is stuck in 3 seconds, the success rate of consecutive requests is not less than 70%. It is recommended to use asynchronous authentication, don't be like an old lady stringing like a door to try one by one.

3. Storage program selection:

Redis is really fast, but it eats memory, so it's easier to use SQLite. I've seen people save proxies in Excel, and the speed is even worse than a snail's crawl.

III. Core code snippets in detail

Here's a Python example (pseudo-code) for the validation module:

async def check_proxy(proxy).
    async def check_proxy(proxy). try.
         Add a delay to prevent blocking
        async with aiohttp.ClientSession() as session.
            async with session.get('http://httpbin.org/ip', proxy=proxy, async with session.
                                proxy=proxy,
                                timeout=5) as resp: async with session.get('', proxy=proxy, timeout=5) as resp.
                return True if resp.status == 200 else False
    except Exception as e.
         Don't be lazy about exception handling
        log_error(f"{proxy} hung: {str(e)}")
        return False

Note that this timeout parameter is particularly critical, set too short will mistakenly kill a good agent, too long and affect the efficiency. Measured 3-5 seconds is a more appropriate interval.

Fourth, the pit of free agents you do not step on

After two months of messing with the tool myself, I've learned these bloody lessons:

• Don't believe those free agents labeled high stash, nine times out of ten are transparent agents!
• Be wary of unusually fast responses, it may be a honeypot system
• 2-5am agent survival rate is the highest, this time to run more verification

Fifth, really do not want to toss how to do?

If it's too much work to maintain your own agent pool, just go to theipipgoThe commercial services of the company are more hassle-free. Their family's dynamic residential IP pool has a masterpiece - theAutomatic geographic switchingThe data collection can simulate the real user behavior. The last time I helped a client do price monitoring, I used their API to poll IPs, and it ran for 72 hours without triggering a counter-crawl.

Here's the kicker.ipipgoThe Advantage:

• Each IP survives 5-8 times longer than free ones
• Supports customization of IP types by business scenarios (e.g., e-commerce-specific, social-specific)
• Provide automatic retry mechanism for request failure

QA time

Q: What can I do if the free proxy always times out the connection?
A: First check whether the request header is camouflaged in place, and then adjust the timeout threshold. If it is not possible, it is recommended to change theipipgoThe paid service, their home IP pool is maintained by a dedicated O&M team.

Q: How can I prevent my own developed tools from being counter-crawled?
A: Focus on these two points: 1. Randomize the request interval (between 0.5-3 seconds) 2. Regularly change the User-Agent. you can work with theipipgo's highly anonymized IP, disguising the fingerprint information in a more natural way.

Q: Why does the authenticated agent still fail when I actually use it?
A: This is mostly the case when the target website has IP quality detection. Free proxies are prevalentsharedof the problem, it is proposed to change theipipgoThe stability is directly improved by several orders of magnitude with the exclusive IP resources.