To check if an IP address is on a blacklist, you can go to https://mxtoolbox.com/blacklists.aspx and/or http://www.justspam.org/ check-an-ip
There are several reasons your IP address is on a blacklist or blocklist.
- Your device has been infected with a virus.
- While surfing the web or checking emails, you may have fallen prey to a virus or a piece of malicious software.
- There may be an underlying security issue on your home/office network.
- Spam emails may have been sent from a device on your home network, such as a computer, phone or tablet infected with malware.
With all the above, it is the IP address that has been reported and blacklisted. IP addresses are being reused all the time. That means it could have been someone who previously used the IP address, you are now using.
With home or office broadband connections, your IP address usually stays the same, unless you restart your router, but with mobile broadband/data connections, your IP address my change many times a day. Mobile broadband/data connections are more likely to be used by hackers or spammers and it is quite common for whole ranges of IP addresses to be added to a blacklist. Even all IP addresses belonging to a mobile phone network provider.
Why is your website firewall blocking blacklisted IP addresses?
Hundreds of times a day, automated software used by hackers and spammers, are constantly trawling the internet, looking for vulnerable website, forms to send spam through or to create fack user accounts. By blocking IP addresses that appear on blacklists, we can stop a large number of these attacks. We can also block IP addresses by country. We find by blocking Russian and Chinese IP addresses, we again can stop a large number of these attacks. So unless you expect to have customers in those countries, it can be a good idea to block the IP addresses from those countries.
If you are concerned that blocking IP addresses may stop legitimate traffic/customers from visiting your website, we can switch off IP blacklist blocking and GeoIP blocking, but you must understand by doing this, you risk increasing the number of fake user accounts being created on your website, risk increasing the number of spam emails you received via your website forms, and risk increasing the number of hack attempts being made on your website.
