instaed of CAPITALS, I used simple letters as below.


iptables -A INPUT -i eth0 -d 192.168.101.60 -p tcp -m state --state established,related -j ACCEPT

But I can not use -A INPUT as  -a input, then it does not work.

Anyway, I would like to get more help as to this.


 I want to know that does "-m state --state established,related -j ACCEPT" work for all tcp,udp and icmp protoclos ? or only for tcp. (for tcp. it works)

I am testing below rule. It is udp.
iptables -A OUTPUT -p udp -o eth0 --dport 53 -m state --state NEW -j ACCEPT
when I have below rule for the above, it works. If I remove it, it will not. WHY?
iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT

pls note that I have already added below rule
iptables -A INPUT -i eth0 -d 192.168.101.60 -p tcp -m state --state established,related -j ACCEPT


Before you ask anything about IPtables, print out the results from

pls see below

[root@firebox rc.d]# iptables -L
Chain INPUT (policy DROP)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             firebox.itabspl.com state RELATED,ESTABLISHED
ACCEPT     all  --  localhost.localdomain  localhost.localdomain
ACCEPT     tcp  --  anywhere             firebox.itabspl.com tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.102.253     tcp dpt:ssh
ACCEPT     icmp --  firebox.itabspl.com  anywhere
ACCEPT     icmp --  192.168.102.0/24     192.168.102.253
ACCEPT     icmp --  66.94.234.13         anywhere
ACCEPT     icmp --  64.233.189.104       anywhere
ACCEPT     icmp --  203.143.4.1          anywhere
ACCEPT     udp  --  anywhere             anywhere            udp spts:traceroute:33523
ACCEPT     icmp --  anywhere             anywhere            icmp echo-reply
ACCEPT     icmp --  anywhere             anywhere            icmp echo-request
ACCEPT     icmp --  anywhere             anywhere            icmp destination-unreachable
ACCEPT     icmp --  anywhere             anywhere            icmp time-exceeded
ACCEPT     icmp --  anywhere             anywhere            icmp type 30

Chain FORWARD (policy DROP)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere            state RELATED,ESTABLISHED
ACCEPT     udp  --  192.168.102.0/24     anywhere            udp dpt:domain
ACCEPT     udp  --  anywhere             192.168.102.0/24    udp spt:domain
ACCEPT     udp  --  192.168.100.3        anywhere            udp dpt:domain
ACCEPT     udp  --  anywhere             192.168.100.3       udp spt:domain
ACCEPT     tcp  --  192.168.102.25       anywhere            multiport dports ssh,smtp,domain,http,https,pop3,imap
ACCEPT     tcp  --  192.168.102.0/24     anywhere            multiport dports http,https
ACCEPT     tcp  --  192.168.100.3        anywhere            multiport dports smtp,http,https
ACCEPT     icmp --  192.168.102.25       64.233.189.104
ACCEPT     icmp --  64.233.189.104       192.168.102.25

Chain OUTPUT (policy DROP)
target     prot opt source               destination
ACCEPT     all  --  localhost.localdomain  localhost.localdomain
ACCEPT     tcp  --  firebox.itabspl.com  anywhere            tcp dpt:ssh
ACCEPT     udp  --  firebox.itabspl.com  anywhere            udp dpt:domain state NEW
ACCEPT     tcp  --  firebox.itabspl.com  anywhere            tcp dpt:domain
ACCEPT     tcp  --  firebox.itabspl.com  anywhere            tcp spt:ssh
ACCEPT     tcp  --  192.168.100.253      anywhere            tcp spt:ssh
ACCEPT     tcp  --  192.168.102.253      anywhere            tcp spt:ssh
ACCEPT     icmp --  anywhere             firebox.itabspl.com
ACCEPT     icmp --  192.168.102.253      192.168.102.0/24
ACCEPT     icmp --  anywhere             66.94.234.13
ACCEPT     icmp --  anywhere             64.233.189.104
ACCEPT     udp  --  anywhere             anywhere            udp dpts:traceroute:33523
ACCEPT     icmp --  anywhere             anywhere            icmp echo-reply
ACCEPT     icmp --  anywhere             anywhere            icmp echo-request
ACCEPT     icmp --  anywhere             anywhere            icmp destination-unreachable
ACCEPT     icmp --  anywhere             anywhere            icmp source-quench
ACCEPT     icmp --  anywhere             anywhere            icmp parameter-problem
ACCEPT     icmp --  anywhere             anywhere            icmp time-exceeded
ACCEPT     icmp --  anywhere             anywhere            icmp type 30
ACCEPT     icmp --  anywhere             203.143.4.1