Firewall Concepts and Firewall Rule understanding

 `Firewall --> Rules of firewall and direction of firewall is very important to manage any firewall. Three rules available for fire wall Filter rule, NAT, Mangle

1. Filter Rule --> When we try to allow/deny web traffic, SSH, Download, Telnet or want to block specific ip, pool we need to setup Filter Rule. 

NAT --> 

Direction of Firewall -- > INPUT  , OUTPUT , FORWARDING

1. INPUT --> Means traffic coming from towards/terminating at firewall

2. OUTPUT--> Means traffic originating from firewall and going towards client/servers

3. FORWARDING --> Means traffic going through firewall (from client to webserver)