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Block a suspicious IP address

NOTE: The steps below should be performed on all instances that receive inbound Internet traffic.

If you have detected an IP address that is collapsing your server or just making suspicious requests, block it using iptables. To do this, run the following command:

$ sudo su
$ iptables -A INPUT -s 1.2.3.4 -j DROP

Remember to replace 1.2.3.4 with the IP address you want to block.

IMPORTANT: Use with caution. If you don’t specify an IP address, you will block yourself.

This will block all requests from that IP address. To have your iptables rules active even after rebooting the server, follow these steps:

  • Execute these commands:

    $ sudo su
    $ iptables-save > /opt/bitnami/iptables-rules
    $ crontab -e
    
  • Edit the above file with your favourite editor and include this line at the end of the file:

    @reboot /sbin/iptables-restore < /opt/bitnami/iptables-rules
    
  • Save the file and exit.

Now, on every boot, the system will load and apply the iptables rules.

To delete a rule, run the following command:

$ sudo su
$ iptables -D INPUT -s 1.2.3.4 -j DROP

This will delete the rule. Remember to replace 1.2.3.4 with a valid IP address.

Rerun the iptables-save command shown previously to make the new rules active even after rebooting the server.