iptables

Table

• nat

• mangle - For the modification of packets, ex:time to live (TTL), type of service (TOS)

• filter

Chain

• INPUT

• OUTPUT

• FORWARD

• PREROUTE

• POSTROUTE

TARGET

• ACCEPT

• DROP

• REJECT

• QUEUE

Policy

If all rules are not match, then go to default policy.

iptables-save *filter :Chain -rule

conntrack tool

It is the ability to maintain connection information in memory.

• conntrack Command

  • table name: conntrack / expect

    • Parameters:

      • -L $table

        List all conntrack in table

      • -D $table

        Delte all conntrack in table

      • -F $table

        Flush all conntrack in table

    • Options:

      • -p $protocol

        ex: tcp, udp