[Gllug] iptables - a quick question

[itsbruce at uklinux.net]

On 11/27/01, 4:56:28 PM, will <will at hellacool.co.uk> wrote regarding 
[Gllug] iptables - a quick question:

> Also, when I nmap the machine the port shows up as being filtered.  Is
> this secure or can people still somehow open up a connection to the port?

They can half-open a connection, which is now nmap detects that it is 
filtered.  To open a usable connection they would have to find out/guess 
your criteria and then spoof the source address.  How hard that is 
depends on where you do allow connections from (lan, isp, open internet 
in descending order of difficulty).

You are, of course, setting firewall rules to detect incoming packets 
with spoofed local addresses.

-- 

Bruce

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