Allows you to dynamically create a list of IP addresses and then match against that list in a few different ways. For example, you can create a `badguy' list out of people attempting to connect to port 139 on your firewall and then DROP all future packets from them without considering them.

--name name
    Specify the list to use for the commands. If no name is given then 'DEFAULT' will be used.

[!] --set
    This will add the source address of the packet to the list. If the source address is already in the list, this will update the existing entry. This will always return success (or failure if `!' is passed in).

[!] --rcheck
    Check if the source address of the packet is currently in the list.

[!] --update
    Like --rcheck, except it will update the "last seen" timestamp if it matches.

[!] --remove
    Check if the source address of the packet is currently in the list and if so that address will be removed from the list and the rule will return true. If the address is not found, false is returned.

[!] --seconds seconds
    This option must be used in conjunction with one of --rcheck or --update. When used, this will narrow the match to only happen when the address is in the list and was seen within the last given number of seconds.

[!] --hitcount hits
    This option must be used in conjunction with one of --rcheck or --update. When used, this will narrow the match to only happen when the address is in the list and packets had been received greater than or equal to the given value. This option may be used along with --seconds to create an even narrower match requiring a certain number of hits within a specific time frame.

--rttl
    This option must be used in conjunction with one of --rcheck or --update. When used, this will narrow the match to only happen when the address is in the list and the TTL of the current packet matches that of the packet which hit the --set rule. This may be useful if you have problems with people faking their source address in order to DoS you via this module by disallowing others access to your site by sending bogus packets to you.

Examples:

    # iptables -A FORWARD -m recent --name badguy --rcheck --seconds 60 -j DROP # iptables -A FORWARD -p tcp -i eth0 --dport 139 -m recent --name badguy --set -j DROP

Official website (http://snowman.net/projects/ipt_recent/) also has some examples of usage. /proc/net/ipt_recent/* are the current lists of addresses and information about each entry of each list. Each file in /proc/net/ipt_recent/ can be read from to see the current list or written two using the following commands to modify the list:

echo xx.xx.xx.xx > /proc/net/ipt_recent/DEFAULT
    to Add to the DEFAULT list

echo -xx.xx.xx.xx > /proc/net/ipt_recent/DEFAULT
    to Remove from the DEFAULT list

echo clear > /proc/net/ipt_recent/DEFAULT
    to empty the DEFAULT list.

The module itself accepts parameters, defaults shown:

ip_list_tot=100
    Number of addresses remembered per table

ip_pkt_list_tot=20
    Number of packets per address remembered

ip_list_hash_size=0
    Hash table size. 0 means to calculate it based on ip_list_tot, default: 512

ip_list_perms=0644
    Permissions for /proc/net/ipt_recent/* files

debug=0
    Set to 1 to get lots of debugging info