Re: Is there a way to avoid miscreants?

On 4/4/26 6:50 AM, Alessandro Vesely wrote:
> Hi,

Hi,

> yesterday I got 124,646 queries in ten minutes, between 1:50 and 2:00 AM 
> UTC, from 4,287 different IPs.  The top IP was 
> 2001:19f0:5401:2e01:5400:3ff:fed1:9863 with 47,304 queries for 5,261 
> subdomains, e.g. serverselect.tana.it,  nu.tana.it,  ll.tana.it, 
> ghsms.tana.it,  dragoner.tana.it,  cinemathe.tana.it,  bluefire.tana.it, 
> umk.tana.it,  tyche.tana.it,  tsvb.tana.it.

I'm not sure how to filter for sub-domains.

In the distant past I've  used iptables' L7 filtering capability to 
filter  out queries for a fixed domain name.  In short, I constructed 
the hexadecimal sequence at a position to look for and dropped the packet.

I don't remember the domain name, but it had "pizza" in it.

I can probably look for old config if it will help.

But that was for a known domain name and you're being hit with thousands 
of sub-domains.

I would consider standing up an empty zone for tanta.it.  But I don't 
know how much good that would do as the queries are still hitting your 
system.

> When I designed the firewall, I didn't bother monitoring UDP connections 
> to port 53.  It seemed to me like named could take care of itself.  
> However, I didn't configure any intrusion prevention features either.  
> Are there any I should enable?

response rate limiting (see Nick's reply).

I'm surprised that the queries came from so many different (likely 
spoofed) IPs.  It seems like if it was a reflected attack (to likely 
spoofed IPs) there wouldn't be that many sources.  Was there any 
commonality to the source IPs?  Aggregate network?  ASN?



-- 
Grant. . . .
unix || die
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