do help do iptables
#man iptables
REJECT
This is used to send back an error packet in response to
the matched packet: otherwise it is equivalent to DROP.
This target is only valid in the INPUT, FORWARD and OUTPUT
chains, and user-defined chains which are only called from
those chains. Several options control the nature of the
error packet returned:
TARGETS
A firewall rule specifies criteria for a packet, and a
target. If the packet does not match, the next rule in
the chain is the examined; if it does match, then the next
rule is specified by the value of the target, which can be
the name of a user-defined chain or one of the special
values ACCEPT, DROP, QUEUE, or RETURN.
ACCEPT means to let the packet through. DROP means to
drop the packet on the floor. QUEUE means to pass the
packet to userspace (if supported by the kernel). RETURN
means stop traversing this chain and resume at the next
rule in the previous (calling) chain. If the end of a
built-in chain is reached or a rule in a built-in chain
with target RETURN is matched, the target specified by the
chain policy determines the fate of the packet.
Drop means to drop the packet on the floor
o que significa isso? Que eu saiba eh simplesmente dropar o pacote e nao retornar nada
e reject e ~send back an error packet~ .... alguem poderia me explicar isso?