The command iptables

Create some very basic firewall rules with iptables. All rules and chains created at the command prompt will be deleted after next reboot. For a permanent use you have to set them in a boot script.

Drop all incoming packets of all protocols from sender (ip address or URL)

iptables -A INPUT -j DROP -s sender

Reject all incoming icmp packets (then the server cannot be pinged)

iptables -A INPUT -p icmp -j REJECT

List all rules of all chains with line numbers

iptables -L --line

Delete rule 1 from chain INPUT

iptables -D INPUT 1

Delete all rules of a chain

iptables -F chainname

Create your own chain to group several rules

iptables -N chainname

Delete a chain

iptables -X chainname

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