How IP Classification and CGNAT Affect Your Scraping Strategy

Web scraping has become an essential tool for extracting valuable data from websites, but one of the biggest challenges scrapers face is IP blocking. Web servers use various techniques to recognize and block scraping attempts, including IP classification, rate-limiting, and identifying traffic from data centers or suspicious sources. Understanding how IP addresses are classified and how technologies like CGNAT (Carrier-Grade NAT) work is critical for overcoming these challenges. This article will explore IP recognition methods, the role of CGNAT, and how proxy solutions can help mitigate blocks while scraping the web.

For a broader introduction to web scraping and its techniques, check out our guide on What is Web Scraping?.

The Importance of IP Classification in Web Scraping

When a web server receives a request, it identifies the IP address from which the request originated. This IP address provides the server with information about the origin of the request. Servers use multiple techniques to classify IP addresses into categories such as residential, mobile, data center, ISP, or VPN/proxy. Based on this classification, web servers can make decisions about how to respond to incoming requests.

How Web Servers Classify IP Addresses

Several methods are used to classify IP addresses, including:

IP Databases: Services like MaxMind’s GeoIP and IP2Location maintain extensive databases that associate IP addresses with particular organizations, ISPs, and types of networks. These databases are regularly updated and are a primary resource for servers to identify whether an IP is associated with a residential ISP, mobile carrier, or data center.
Autonomous System Number (ASN): Each IP address is part of a network managed by an organization, identified by an ASN. Data centers often have their own ASNs, while residential ISPs have theirs. By analyzing the ASN of an IP address, web servers can determine whether it belongs to a residential user, an ISP, or a data center—an important flag for scraping.
Reverse DNS Lookups: By looking up the domain associated with an IP address (reverse DNS), servers can infer the nature of the request. If an IP address resolves to a known data center, ISP, or VPN provider, the request is more likely to be blocked.
Behavioral Heuristics: In some cases, web servers track patterns of requests to detect abnormal behavior. High request rates, unusual browsing patterns, or sequential scraping from the same IP address can all trigger blocks.

What is CGNAT?

CGNAT, or Carrier-Grade Network Address Translation, is a technique used by Internet Service Providers (ISPs) to conserve public IPv4 addresses, which have become scarce due to the explosion of devices connected to the internet. The global pool of IPv4 addresses was officially exhausted in 2011, and despite the introduction of IPv6, many ISPs still rely on CGNAT to stretch their remaining IPv4 resources.

How CGNAT Works

In a typical home or office setup, your router performs Network Address Translation (NAT) between your private, local network and the public internet. Your internal devices (e.g., your computer, phone, or smart TV) are assigned private IP addresses that are only valid within your local network. When a device sends a request to the internet, the router translates the private IP to a public IP and manages the connections, so that responses from the internet know which internal device to return to.

CGNAT works similarly but on a much larger scale. Instead of translating IPs between your home network and the public internet, CGNAT allows ISPs to map multiple private networks (i.e., thousands of customers) onto a smaller pool of public IP addresses. Under CGNAT, many users share the same public IP, making it difficult for external services to distinguish between individual users on the same ISP.

For instance, in a CGNAT setup:

Private IPs: Each customer is assigned a private IP address that is unique within the ISP's local network but not on the public internet.
Public IPs: The ISP assigns a shared public IP to a group of customers, so when multiple users access the internet, they all appear to have the same public-facing IP address to external servers.

This setup significantly reduces the number of public IP addresses that ISPs need to allocate, allowing them to continue supporting IPv4 connectivity.

Implications of CGNAT for Web Scraping

CGNAT can both help and hinder web scrapers, depending on how it’s used. On one hand, because multiple users share the same public IP, it can obscure the identity of an individual scraper, making it harder for a target server to pinpoint and block a specific IP. In this sense, CGNAT can act as a layer of anonymity for scraping activities.

However, this same benefit can quickly become a downside. If one user sharing the same CGNAT public IP engages in scraping or other suspicious behavior, the entire group of users behind that IP could be blocked or rate-limited by the server. Since the server sees the shared public IP as one user, the activities of one individual can affect everyone behind the CGNAT.

Additionally, services and websites may view traffic coming from a CGNAT IP with suspicion, especially if the IP makes an unusually high number of requests. Rate-limiting or captchas might be triggered more easily, as web servers may assume that the traffic volume is too high for a typical individual user.

CGNAT's Effect on IP-based Identification

When scraping from an IP address that is part of a CGNAT pool, websites might find it difficult to trace the activity back to a single user. This is because the same public IP can represent hundreds or even thousands of customers. While this can offer some protection for web scrapers, it can also lead to a higher likelihood of being blocked if too much traffic originates from that IP.

CGNAT can cause issues in the following areas:

Shared Accountability: Since many users share the same public IP, bad behavior from one user can affect others. A blocked IP might impact all users under the CGNAT, even if only one person engaged in suspicious activity.
Difficulty in Bypassing Geofences: CGNAT’s shared public IP can make it hard to scrape region-locked content, as multiple users from different locations may appear to come from the same IP.
Increased Rate-Limiting: A high volume of requests from a single CGNAT IP could trigger rate-limiting or captchas, even if your scraping is modest in scale, simply due to the aggregate traffic from other users.

CGNAT in Comparison to Traditional NAT

While traditional NAT is limited to your home or office network, CGNAT operates on a much broader scale. Both forms of NAT translate private IP addresses into public ones for internet communication, but the primary difference is the scale and purpose:

NAT: Typically performed by a home router, NAT allows multiple devices in your home to share a single public IP address when accessing the internet.
CGNAT: Performed by the ISP, CGNAT enables hundreds or even thousands of customers to share a smaller pool of public IPs, conserving IPv4 address space.

Despite the widespread use of CGNAT, IPv6 is the long-term solution to address exhaustion, as it offers a virtually limitless pool of IP addresses. However, full IPv6 adoption is still years away, so CGNAT remains a crucial technology for ISPs that are still reliant on IPv4.

How Proxies Help Overcome IP Identification Challenges

To overcome IP blocking and classification issues, scrapers often turn to proxies. A proxy routes your requests through a different IP address, effectively masking your real IP from the target server. However, not all proxies are created equal, and selecting the right type of proxy is crucial for avoiding blocks.

Tailscale: A VPN Alternative for Secure Scraping

Tailscale is a tool that creates a secure, encrypted private network between your devices, using a protocol called WireGuard. Unlike traditional proxies, Tailscale creates a mesh network between devices you control, allowing you to route your scraping requests through your home network or another trusted network.

By using Tailscale, you can:

Mask your scraping traffic by routing it through a trusted network that won’t be flagged as suspicious.
Avoid IP-based blocks by appearing as a typical residential user, rather than coming from a known data center or commercial proxy service.
Encrypt traffic, protecting your scraping activities from being monitored or intercepted by third parties.

This approach is ideal for small-scale scraping operations where you have control over your networks and don’t require massive IP rotation.

Scrapoxy: Rotating Proxies with Data Center and Cloud Integration

Scrapoxy is another popular solution for web scraping, allowing users to manage a pool of proxy servers from cloud providers like AWS, Azure, and DigitalOcean. Scrapoxy acts as a proxy manager that automatically rotates your IPs to prevent web servers from detecting scraping patterns.

The key benefit of Scrapoxy is its ability to:

Rotate IPs dynamically by spinning up and down cloud instances, making your requests appear as if they come from different locations.
Avoid bans and rate limits by changing your IP frequently, ensuring that no single IP address makes too many requests in a short period.

However, since Scrapoxy relies on data center IPs, it may still be subject to classification and blocking.

Squid: Open-Source Proxy Caching for Flexibility

Squid is a widely used open-source proxy solution that offers web caching and supports HTTP, HTTPS, and FTP protocols. Squid is highly customizable, making it an excellent choice for web scrapers who need control over how their proxy system behaves.

With Squid, you can:

Cache frequently requested pages to reduce bandwidth usage and speed up scraping.
Configure IP rotation with external scripts or services to avoid bans.
Filter traffic and route requests through different networks based on your needs.

Squid is often used in combination with other proxy solutions, like residential and mobile proxies, to enhance anonymity and efficiency.

Commercial Proxy Solutions: Residential, Mobile, and ISP Proxies

Commercial proxy providers like Luminati, Bright Data, and Smartproxy offer residential, mobile, and ISP proxies, which are highly effective for web scraping. These types of proxies have different characteristics and offer varying levels of success when it comes to avoiding blocks.

How Proxy Vendors Offer Residential, Mobile, and ISP IPs

Residential IPs: Proxy vendors partner with end users or device manufacturers to use their internet connections as exit nodes. For example, some proxy providers offer consumers incentives (like free VPN services or reduced internet costs) in exchange for allowing their internet connection to be used as a proxy node. These residential IPs are then rented out to web scrapers who need to appear as legitimate users.
Mobile IPs: Proxy providers source mobile IPs from users connected to 3G, 4G, or 5G networks. These mobile IPs are constantly changing due to the dynamic nature of mobile carrier networks, making them more resilient to blocks and especially useful for scraping mobile-specific content.
ISP IPs: ISP proxies are similar to residential IPs, but they are issued by internet service providers directly and not tied to a specific residential address. ISP proxies appear as legitimate IPs from an ISP’s pool but offer greater flexibility for managing multiple sessions. These are often regarded as a middle ground between residential and data center IPs in terms of trustworthiness and speed.

Residential vs. ISP Proxies: Similarities and Differences

Both residential and ISP proxies are considered trustworthy compared to data center IPs, as they originate from real ISPs. However, there are important differences:

Source: Residential proxies are tied to specific homes and internet users, while ISP proxies are sourced from ISP pools but are not tied to any particular address.
Blocking Risk: Residential proxies generally have a lower risk of being blocked because they mirror the typical behavior of home users. ISP proxies, while less likely to be blocked than data center IPs, might still face scrutiny because they are not tied to a specific user or household.
Use Case: Residential proxies are ideal for highly anonymous, region-specific scraping, whereas ISP proxies are suited for high-volume tasks that require speed and flexibility but still need some level of trust from the target server.

Both types of proxies are highly effective for web scraping, with residential IPs facing blocking rates as low as 10-20%, while ISP proxies offer similar reliability with a slight trade-off in anonymity due to their pool-based nature.

According to recent studies, data center IPs are blocked 90-98% of the time, while residential proxies face blocking rates as low as 10-20%. Mobile proxies, due to their dynamic nature, are even less likely to be blocked, with failure rates often under 5%.

For more on the role of proxies in web scraping, visit our comprehensive guide on Mastering Web Scraping Proxies.

Key Takeaways for Scraping Successfully

Web scraping is becoming increasingly difficult as websites implement stricter measures to identify and block unwanted traffic.

Proxy solutions play a crucial role in masking your IP address and ensuring the success of your scraping efforts. Please keep in mind though that it’s also paramount to abide by the ethical guidelines of web scraping to ensure compliance with website terms and maintain the integrity of your scraping operations.

For scrapers looking for reliable proxy solutions and an efficient scraping API, Ujeebu provides access to a robust set of proxy types designed to help you navigate these challenges with ease. With the right understanding and tools, your web scraping operations can remain efficient and undetected.