Hello,
Grant Taylor a écrit :
I personally have known that using "-m state --state
ESTABLISHED,RELATED" was not the most secure thing to use for returning
traffic. Namely this will allow you to make a valid connection to a web
server, say to retrieve a picture. Then said web server could send
malicious traffic back to your computer and pass through your firewall.
This is because the traffic coming from the web server to your computer
is now deemed as RELATED.
I do not agree with this. AFAIK the only traffic that can be labelled
RELATED to an HTTP connection or any "simple" TCP or UDP or whatever
connection (not special protocols such as FTP) is some ICMP signalling
messages. This said, I do filter out some RELATED ICMP types I do not like.
"Hole punching" is a completely different thing and requires active
cooperation from the inside.
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