I cannot enter a website: causes and reasons
We are sure that, on some occasions, you have tried to enter a web page and an error message appears, and even a message indicating that we are prohibited from access with the message “Forbidden”, or directly indicates that we do not have the necessary permissions to access said website. The administrators of a website can block different users to prevent them from accessing, the reasons are very varied, although they all have their own logic. However, we already anticipate that many of the locks that can be made on a website, we could skip them with different tools and tricks.
The main reasons why you cannot enter a website are varied, although they all have their logic, and it is completely normal that they have decided to block you based on a series of compelling reasons.
Public IP on a blacklist
Our public IP address provided to us by the internet operator may be on a blacklist, also known as a blacklist. Websites typically have tools with the aim of banning access from IP addresses that are in different databases of malicious IP addresses, spammers, malware distribution, and more. It is very likely that you are not a spammer nor do you dedicate yourself to the distribution of malware, but since your IP address is on this list, you will be blocked. Above all, in the main Internet forums, tools are incorporated to prevent unauthorized registration by blocking source IP addresses that are widely known as spammers.
The easiest solution to get out of this black list is to change your public IP address, restarting your WiFi router so that the operator provides you with another one that is not on this black list. If you have a fixed IP address, then changing the IP is more complicated, also, you could lose access to your servers. In this case, you could contact different blacklist databases, and wait until the database updates and removes your public IP address from the list. However, the easiest way to enter the websites that have detected you is by changing your IP using a VPN or Proxy service.
User blocked for different reasons
If you try to enter a website without logging in and you can enter without problems, but when you log in with your registered user is when it tells you that you cannot visit the website, it is very likely that the user has been banned (and it is also possible that your IP address has been banned). This happens because you have committed an infraction to the rules of the website or forum, and you have been banned temporarily or permanently, therefore, you should take it into account.
To avoid this, our recommendation is that you change the public IP, and re-register using a completely different nickname and another email account, because they will also have blocked the email address used in the previous registration.
The main websites of streaming services and Internet TV, limit their services only to a certain country, not being able to access from another different country. For example, if we try to enter websites like Atresplayer from other countries, it will indicate that we are not allowed to see any type of content outside of Spain, because they have imposed a regional block on us, but this would happen to anyone who tries to access outside of Spain .
If you are physically in Spain and you get this message, it is probably because the database of Spanish IP addresses they use is not up to date, and you have a public IP that in the past was hosted in countries like France (it can happen if you have Orange) , or in other countries where operators have bought IP addresses because they have already exhausted the previous ones. What you can do in this case is, either restart the router so that they provide you with another public IP that is cataloged as Spanish, or use a VPN service that is in Spain to bypass this geo-blocking.
Block for using ad blocker
When we use an ad blocker in our web browser, such as uBlock Origin or the popular AdBlock Plus, it is very likely that on certain websites you will not be able to enter. This is because they have ad blocker detectors, and they prevent you from entering unless you disable the ad blocker. To be able to enter you have two main options, or deactivate the ad blocker, or configure it in an advanced way so that it also blocks the ad blocker detector.
The latter is the most effective, we will be blocking all the ads and we will be able to access the web without limitations, but it is also the most complicated since you will have to inspect what is detecting you and how to do it, so the simplest thing is disable ad-blocking only on that specific website.
How do they block me when accessing a website
Websites normally block users via IP address, by banning an IP address the website will check the source IP address and block all requests that it is making, of course this can also be configured at the level of firewall, preventing any communication with a specific source IP. Blocking through the firewall can be done on the web server directly with the typical ModSecurity, or directly on the firewall that is placed in front of the web server to protect it from DoS and DDoS attacks.
In the event that the website has a registration, then they will block you based on the nick used in the registration, the IP address associated with said nick, and also the email you used in the registration, that is, all the data that you have provided to the website previously. If you want to re-enter and need registration, our recommendation is to first change the IP address so that you cannot be associated with the previous nick, use a new nick and also registration email.
Blacklist-based blocking occurs directly at the firewall in most cases, to prevent both spam attacks and denial of service (DoS) attacks, but it depends on how the site is configured web, because it could also be done at the web server level (L7 application layer firewall) instead of the L3 firewall.
As you have seen, there are many reasons why we will not be able to access a certain web page, and also many different methods to bypass the different blocks if they do so.