There's been quite a few spam{bots,turks} lately passing through Drupal Captcha , reCAPTHA, Honeypot module… After a bit of research, I decided to block China from accessing my site. It turned out to be easy:
# install geoip filter into iptables apt-get install xtables-addons-common # download the existing geoip database /usr/lib/xtables-addons/xt_geoip_dl # set up csv parser in perl apt-get install libtext-csv-xs-perl # create a directory for geoip filter's database mkdir /usr/share/xt_geoip # build the database /usr/lib/xtables-addons/xt_geoip_build -D /usr/share/xt_geoip *.csv # load the geoip filter module modprobe xt_geoip # block China iptables -A INPUT -m geoip --src-cc CN -j DROP
PROFIT!!!
P.S. Next in sight is US. US an CH account for 97% of Drupal spam.