Network secuirty command "iptables" in unix/linux

Description :

Rules that allow packets to be filtered by the kernel are put in place by running the iptables command.

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   iptables [-t table] -[AD] chain rule-specification [options]
   iptables [-t table] -I chain [rulenum] rule-specification [options]
   iptables [-t table] -R chain rulenum rule-specification [options]
   iptables [-t table] -D chain rulenum [options]
   iptables [-t table] -[LFZ] [chain] [options]
   iptables [-t table] -N chain
   iptables [-t table] -X [chain]
   iptables [-t table] -P chain target [options]
   iptables [-t table] -E old-chain-name new-chain-name

  
  

to view the rules that are currently applied --------> iptables -L(it will list the rules)

rules to network packets that are either inbound (INPUT), outbound (OUTPUT), or being forwarded through your server (FORWARD)

some iptable rules

a server that will block every inbound connection

iptables -P INPUT DROP

it accepts all the output connections

iptables -P OUTPUT ACCEPT

it drops all the forwarding connections

iptables -P FORWARD DROP


it allows for internal host connectivity through local

iptables -A INPUT -i lo -j ACCEPT

it allows port 80 tcp requests that are inbound to also go through

iptables -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT