What does this iptables rule do?

Question

linux

Can you help me figure out what this rule does?

# Generated by iptables-save v1.4.7
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [52839:6255656]
-A INPUT -i lo -j ACCEPT
-A INPUT -p udp -m udp -s 188.163.11.25 --sport 1191 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
-A OUTPUT -o eth0 -p udp -m udp -d 188.163.11.25 --dport 1191 -j ACCEPT
-A OUTPUT -o wlan0 -p udp -m udp -d 188.163.11.25 --dport 1191 -j ACCEPT
-A OUTPUT -o tun0 -j ACCEPT
-A OUTPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT

Only the request is very precise, it is important.

Answer 1

1. :INPUT ACCEPT[0:0]
   Rules 1, 2 and 3 set the default policies to ACCEPT. Those. if the packet does not fall into any of the rules below it, then it falls into one of these three.
   4. Allows all incoming packets from the lo interface
   5. Allows incoming packets in the RELATED,ESTABLISHED state only from the remote host 188.163.11.25 and only on port 1191\UDP
   6. Allows incoming packets in the RELATED,ESTABLISHED state only from the tun0 interface
   7. All other incoming packets are dropped with the message host is prohibited (icmp-host-prohibited)
   8. All transit packets are dropped with the message host is prohibited
   9. Allows outgoing packets from interface eth0 to remote host 188.163.11.25 and port 1191\UDP
   10. Similar to 9, only from interface wlan0
   11. Allows all outgoing packets from the tun0 interface
   12. Drops all other outgoing packets with the message host denied