What Is IP Address Blacklisting And How To Fix It?

IP address blacklisting is the act of limiting access to specific IP addresses from using a product or service. This is, for example, used by email service providers, search engines, and online services to blacklist users and organizations who spam, phish, brute force hack, or commit cybercrimes.

There are several reasons why your IP address may get blacklisted, and in this article, we will discuss how this can happen and how to fix it.

The basics: what is an IP address?

In technical terms, an IP address is the digital connotation of a DNS system. In more straightforward terms, it is the address that every device connected to a network is given for two primary purposes: 

1. identification of the network and host interface
2. the address location

Each device is provided with a unique IP address, which has its numerical configuration restricted to its use for the time. Every action that your device makes on the internet does so through its IP address.  

Think of the internet as a town; your IP address is your identity within that town.  

Initially, ipv4 was the system used for making IP addresses, but in 1995, ipv6 was introduced. Still, in everyday practice, ipv4 is used. To make it a bit easier, here’s what a standard ipv4 address looks like. 

192.168.8.102

Each Ipv4 address contains 32 bits and is divided by octets through the numbers’ dots. Making 192 an octet, followed by 168 followed by 8 and 102. The first three octets define the identity of the network, while the last octet defines the host.  

All in all, an IP address makes your function and identification both clear.

What is IP address blacklisting?

Every individual connection is meant to connect and work on the internet peacefully. So, when an IP address starts performing disruptively, it gets blacklisted from specific sites. Typically behavior such as spam, malicious malware, or hacking leads towards blacklisting of a particular IP address.

What is a blacklist?

A blacklist is typically a centralized database that curates a list of spam, malware, or cybercrime offenders shared online. These blacklists are maintained by different organizations and used by service providers to filter the good from the bad.

For example, the most popular blacklist includes the Composite Blocking, SBL and XBL exploit block list by Spamhaus and SpamCop, passive spam block list (PSBL, invaluement, etc barracuda, and senderscore to name a few of the hundreds of DNS-Based Realtime Blacklists,(DNSRBL).

There are two mechanisms through which IP addresses are blacklisted.

IP based: 

IP-based blacklisting occurs when the operator blocks the IP address of the device wholly.

Domain Based:

Domain-based blacklisting or DNSBL (domain name system blocklist) looks through the entire content and email to find keywords in the domain name and then blocks the IP address.

Criteria for IP Address Blacklisting:

There’s a criterion that guides the blacklisting of sites, and if you’re confused about why a specific IP address is blacklisted, then this is the policy foundation.

1. Technical issues:

Sometimes certain configuration issues lead towards blacklistings, such as backward or even wrong DNS, a problem in the Mail Operation System, or an issue in the simple mail transfer protocol (SMTP)

2. Evidence-based

Evidence-based blacklisting occurs when the device used by the IP address has been observed pragmatically to be taking part in spam, hacking, or other suspicious behavior. 

3. Policy Listing

This has little to do with the IP address activity itself and concerns the recipient site’s internal policy. The recipient site might have a blacklisting policy against a country or region etc. 

How are potential blacklist IP addresses found?

This is the fun part. 

One way of finding an IP address is, of course, when it falls into your lap and sends you spam emails. But another way of finding such elusive patterns used by companies is by sending trap emails.  

A trap email is an email sent by companies to different IP servers. When such an email enters the potential blacklist IP address data, it saves it in future spam sending. When it picks the email and IP address for serving unsolicited content during the RCTP part of the Simple Mail Transfer Protocol, the trap email finds it and reports it for blacklisting.

A trap email looks somewhat like this,

[email protected]

How to get whitelisted again?

There are different ways of getting whitelisted:

It might be automatic because specific sites and links hold a finite and defined period after which the blacklisted IP addresses are removed from the list.  

So it’s time-based, and there’s close to nothing that you could do in the meantime to get yourself removed. You might want to wait for some time and then re-check with the site. 

It can also be manual. Manual removal from the blacklist is also not a very complicated issue. Specific sites have the option of removing an IP address from the blacklist if it follows a set of guidelines and, in the future, would not continue its actions. 

Hexometer will notify you which blacklist has blacklisted your IP, so you can find the blacklist organization and request removal after fixing the problem.

But it’s important not to get blacklisted once you’ve been whitelisted! Removing yourself from the blacklist a second time might be somewhat challenging.

How to prevent getting blacklisted?

There are several things that you can do in order not to get blacklisted. Some of these are mentioned below.

Check your IP address for solitary use.

Remember when we said that there had been a transition from ipv4 to ipv6 at the start? 

This occurred because ipv4 was not meeting the demands of the vast demographics surging into technological advancement. Basically, the 32-bit numerical figure was subject to repetition, and different devices connected with the same IP addresses.  

Today, ipv6 has still not met everyday use, and because of that, different servers might still be using the same IP address with little and very hard to see the distinction. So, you might get blacklisted for actions that never emerged from your side. 

Check with your ISP about the solitary use of the IP address you hold.

Use Hexometer; the ultimate blacklist monitoring tool

Many tools are present on the internet to prevent viruses and hackers from entering or leaving the servers. This is important because such tools prevent massive collateral damage and function otherwise, such as antiviral shields. 

One of the most useful tools in this regard is Hexometer. It provides daily IP blacklisting monitoring to detect such issues and alert you so you can take prompt action as soon as possible to unblock your organization or IP.

Key Takeaway

Blacklisting is a serious issue and requires careful attention at the individual as well as institutional level. We hope this helped you understand how and why an IP address gets blacklisted and what to do if it happens!

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