IPtables

Exact meaning of an option which are used in iptable command: ––––-
A – All source
I – INPUT
s – Source
j – jump on
––––-
Procedure:
For Example: If you want to check IP 49.248.23.83 is blocked or not then fire command

iptables -nL | grep 49.248.23.83

You can see the result as below

DROP all — 49.248.23.83 0.0.0.0/0
DROP all — 0.0.0.0/0 49.248.23.83

 

Which means IP is blocked To unblock that IP address use following command:

iptables -I INPUT -s 49.248.23.83 -j ACCEPT

 

To Block back an IP Address:

 

iptables -A INPUT -d 49.248.23.83 -j DROP

After adding or removing ips from iptables you need to save iptable rule using following command.

service iptables save

 

service iptables restart

 

To allow PORT in iptables you have to follow below commands Exact meaning of an options which uses in the command
=====================================
p – protocol

dport – destination port
j – jump on
=====================================

iptables -I INPUT -p tcp –dport 2082 -j ACCEPTiptables -I INPUT -p udp –dport 2082 -j ACCEPT
iptables -I OUTPUT -p tcp –dport 2082 -j ACCEPT
iptables -I OUTPUT -p udp –dport 2082 -j ACCEPT

To drop (block) port in iptables you have to follow below commands:

iptables -I INPUT -p tcp –dport 2082 -j DROP
iptables -I INPUT -p udp –dport 2082 -j DROP
iptables -I OUTPUT -p tcp –dport 2082 -j DROP
iptables -I OUTPUT -p udp –dport 2082 -j DROP

After adding or removing iptables you need to save iptable rule using following command.

• service iptables save

• service iptables restart

To enable range of port in iptables

 

iptables -A INPUT -p tcp –destination-port 1568:1570 -j ACCEPT iptables -A OUTPUT -p tcp –source-port 1568:1570 -j ACCEPT

 

• service iptables save

• service iptables restart