Rules duplicated in iptables?

[beneix]

I have realised that I need to increase my understanding of iptables, so I started by looking at what I have at the moment. There seems to be a fair few lines that are repeated – is that really the way it should be? I suspect that the Luci interface has created these duplicates, but I would like to know before I do anything that it is safe to remove them. Here are some examples:

root@OpenWrt:~# iptables -L 
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere             /* !fw3 */
input_rule  all  --  anywhere             anywhere             /* !fw3: Custom input rule chain */
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED /* !fw3 */
syn_flood  tcp  --  anywhere             anywhere             tcp flags:FIN,SYN,RST,ACK/SYN /* !fw3 */
zone_lan_input  all  --  anywhere             anywhere             /* !fw3 */
zone_lan_input  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_input  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_input  all  --  anywhere             anywhere             /* !fw3 */
zone_SmartDNS_input  all  --  anywhere             anywhere             /* !fw3 */

Chain FORWARD (policy DROP)
target     prot opt source               destination         
forwarding_rule  all  --  anywhere             anywhere             /* !fw3: Custom forwarding rule chain */
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED /* !fw3 */
zone_lan_forward  all  --  anywhere             anywhere             /* !fw3 */
zone_lan_forward  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_forward  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_forward  all  --  anywhere             anywhere             /* !fw3 */
zone_SmartDNS_forward  all  --  anywhere             anywhere             /* !fw3 */
reject     all  --  anywhere             anywhere             /* !fw3 */

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere             /* !fw3 */
output_rule  all  --  anywhere             anywhere             /* !fw3: Custom output rule chain */
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED /* !fw3 */
zone_lan_output  all  --  anywhere             anywhere             /* !fw3 */
zone_lan_output  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_output  all  --  anywhere             anywhere             /* !fw3 */
zone_wan_output  all  --  anywhere             anywhere             /* !fw3 */
zone_SmartDNS_output  all  --  anywhere             anywhere             /* !fw3 */
<output truncated>

[jow]

By default, iptables hides various rule details like additional match criteria. Use the -v flag to display complete rules: iptables -v -L