DNS rebinding

DNS rebinding

[Stephen Clark]

Hello List,

There is an article about DNS rebinding at the following site:
http://crypto.stanford.edu/dns/


"Circumvention-Resistant Firewalls. Firewalls can prevent
their own circumvention by forbidding external host
names from resolving to internal IP addresses, preventing
the attacker from naming the target server, either by filtering
packets [6] or by modifying their DNS resolver."

Can netfilter be setup to keep dns responses from pointing to internal addresses by filtering the packets? If so how would one go about setting that up.

Thanks,
Steve
-- 

"They that give up essential liberty to obtain temporary safety, 
deserve neither liberty nor safety."  (Ben Franklin)

"The course of history shows that as a government grows, liberty 
decreases."  (Thomas Jefferson)

Re: DNS rebinding

[Patrick McHardy]

Stephen Clark wrote:
> Hello List,
> 
> There is an article about DNS rebinding at the following site:
> http://crypto.stanford.edu/dns/
> 
> 
> "Circumvention-Resistant Firewalls. Firewalls can prevent
> their own circumvention by forbidding external host
> names from resolving to internal IP addresses, preventing
> the attacker from naming the target server, either by filtering
> packets [6] or by modifying their DNS resolver."
> 
> Can netfilter be setup to keep dns responses from pointing to internal
> addresses by filtering the packets? If so how would one go about setting
> that up.

No, that would require a dns match. But IIRC someone posted something
like that based on nfnetlink_queue a couple of month ago ..