PGSQL x iptables

Hello,

we're using PG and Application Server (JBoss) on separate CentOS servers
with Cisco PIX in between. On DB side is iptable with following relevant
rules:

1. -A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

2. -A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp -s
aaa.bbb.ccc.ddd --dport 5432 -j ACCEPT

3. -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited

I was wondering when these rules are not OK for our environment. It
seems that rules 1 and 2 sometimes pass packets and therefore these
packets are rejected. Such connection is then in some weird state,
doesn't communicate (obviously - packets are dropped) and psql (or
JBoss) connection is blocking for a long time (at least few hours).

Everything seems to be OK when I have changed rule 2 to "-A
RH-Firewall-1-INPUT -m tcp -p tcp -s aaa.bbb.ccc.ddd --dport 5432 -j
ACCEPT".

I'm really confused - what other states are possible for iptables except
ESTABLISHED, RELATED or NEW? In iptables manpage is only INVALID, but
why is this state emerging?

Any idea?

Lukas