Are packets "ACK FIN URGP" secure?

[Bruno Negr�o]

Hi all, I'm runing a red hat linux 7.2 kernel 2.4.9-13 and iptables-1.2.4-2 . I have two iptables rules that log-and-drop "new not syn packets": $IPTABLES -A INPUT -p tcp ! --syn -m state --state NEW -j LOG \ --log-prefix "INPUT:New not syn:" $IPTABLES -A INPUT -p tcp ! --syn -m state --state NEW -j DROP              the fact is that these rules are dropping a lot of ACK FIN URGP packets, as the log line bellow: Mar 13 18:37:06 skylane kernel: INPUT:New not syn:IN=eth0 OUT= MAC=00:02:55:c0:f d:f1:08:00:02:0b:af:90:08:00 SRC="66.1.93.212" DST=200.19X.XX.X LEN=40 TOS=0x00 P REC=0x00 TTL=43 ID=40237 DF PROTO=TCP SPT=6346 DPT=1436 WINDOW=16060 RES=0x00 AC K FIN URGP=0   My question is: a packet like this can be insecure? Doesn't it function just to finish a connection, instead of start an usecure connection?   And why these packets are not beeing recognized as ESTABLISHED, RELATED packets?   Thank you, -------------------------------------------------  -- Bruno Negr�o -- Suporte  -- Plugway Acesso Internet Ltda.  -- (31)34812311  -- [EMAIL PROTECTED]