Acontece que é possível, usando a meta SET
descrita em iptables-extensions(8)
.
SET
This module adds and/or deletes entries from IP sets which can be defined by ipset(8).
--add-set setname flag[,flag...]
add the address(es)/port(s) of the packet to the set
--del-set setname flag[,flag...]
delete the address(es)/port(s) of the packet from the set
where flag(s) are src and/or dst specifications and there can be no more
than six of them.
--timeout value
when adding an entry, the timeout value to use instead of the default one
from the set definition
--exist
when adding an entry if it already exists, reset the timeout value to
the specified one or to the default from the set definition
Use of -j SET requires that ipset kernel support is provided, which, for standard
kernels, is the case since Linux 2.6.39.
Eu não encontrei, porque não procurei mais depois de encontrar a descrição do módulo set
.