Error when blocking ASN AS14987

webdig

Hi,

I’m facing an issue while using the Blacklist ASN tool.
I’ve tested with several other ASNs and the blocking works correctly, but with AS14987 I get the following error:

**********************************************************************************************

* cPFence Web Security *

* Blacklist ASN Tool *

**********************************************************************************************

Please wait, preparing the blocklist file...

[ERROR] The final blocklist file is empty for AS14987.

Has anyone else encountered this error or knows if there is a specific limitation with this ASN?

Thanks in advance for your help.

cPFence

webdig

Yes, that happens sometimes. Some ASNs have very little or no data available, so the tool ends up generating an empty blocklist.

If that’s the case, you can look up the ASN ranges manually using a service like this:
https://hackertarget.com/as-ip-lookup/

Then block those ranges with the bulk IP block tool in the WebUI.

Tip: don’t go overboard with ASN blocking. Some ASNs are massive, and blacklisting them entirely can hit performance hard. Best approach is to block only when you’re under attack from that ASN, then remove it once things calm down.

webdig

Thanks for the quick reply. That makes sense and I’ll keep it in mind.

Just to clarify, I’m not blocking ASNs blindly — I only blacklist the ones from where I’ve been receiving the most attacks.

Appreciate the guidance and the tip regarding performance impact.