A parte relevante das suas regras é "-update --seconds 60 --hitcount 120", eis o que você precisa saber:
--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. The maximum value for the hitcount
parameter is given by the "ip_pkt_list_tot" parameter of the xt_recent kernel
module. Exceeding this value on the command line will cause the rule to be rejected.