All incoming TCP connections blocked for 5 minutes at random times.

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All incoming TCP connections blocked for 5 minutes at random times.

L2 Linker

At random times all TCP connections from the Internet are blocked (all ports and all IPs) for incoming traffic only.  Websites, mail servers etc are not accessible from the Internet.  UDP and ICMP are not affected.  What could be causing this?

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L2 Linker

Thanks to all who responded.  I was finally able to resolve this problem by by changing zone protection for Untrust from SYN Cookies to Random Early Drop.  

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21 REPLIES 21

Cyber Elite
Cyber Elite

Sounds like a DoS profile that is setup incorrectly and is blocking the destination address (your public IP) or vulnerability protection profile with the same misconfiguration. The default block-ip timeout is 5 minutes, which lines up with what you are running into.

There are no entries under Policy -> DoS Protection.

Is there another location I can look?

@sharam,

If you had any that's where they would be. What does your Vulnerability Protection profile look like for the security rulebase entries allowing this traffic inbound? That would be the next thing I would look at. 

What I am seeing in logs related to the outage is:

 

sharam_0-1594047748081.png

But I am not able to see which rulebase this it related to.


@sharam wrote:

What I am seeing in logs related to the outage is:

 

sharam_0-1594047748081.png

But I am not able to see which rulebase this it related to.


You're showing the detailed log entry.  (You've clicked the magnifying glass next to an entry in the threat log)  To better help point out why this is happening we need to see the main entry.  It looks like this is happening because of a VP profile which is attached to a security policy rule.

 

threat.PNG

L3 Networker

zone protection

Thank you for your response @Brandon_Wertz .  This is the main entry of an event that just happened today:

sharam_0-1594061476300.png

 

Can you please be more specific?  Zone Pro is the first place we looked and changed various config to no effect.

Did you look under Objects -> Security Profiles -> Dos Protection?   Th default block duration is 5 minutes..

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