How can I invoke a shell or Perl script from iptables? - mysql

Question

We're using CentOS and would like to ban several Asian countries from accessing the entire server. Almost every IP we check which has tried to hack into our server is allocated to an Asian country (Russia, China, Pakistan, etc.)
We have an IP to country MySQL database we can efficiently query and would like to try something like:
-A INPUT -p tcp -m tcp --dport 80 -j /path/to/perlscript.pl
The script would need the IP passed in as an argument, then it would return either an ACCEPT or DROP target?
Thanks for the answers, here's my follow up.
Do you know if it is possible though? Having a rule point to a script which returns a target? (ACCPET/DROP)
Not entirely sure how ipset works, will have to experiment I guess, but it looks like it creates a single rule. How would it handle Russia for example, which has over 6000 ranges assigned to it? And we want to add probably 20 - 40 countries in total, so we could end up needing to add in excess of 100,000 ranges. Wouldn't the overhead of a single MySQL query be less taxing?
SELECT country FROM ip_countries WHERE $VAR{ip} >= range1 && $VAR{ip} <= range2
The database we use is freely available here : http://software77.net/geo-ip/
It represents IPs in the database by converting the IP to a number using this formula :
$VAR{numberedIP} = $octs[3] + ($octs[2] * 256) + ($octs[1] * 256 * 256) + ($octs[0] * 256 * 256 * 256);
It will store the start of the range in the "range1" column, and the end of the range in the "range2" column.
So you can see how we'd look up an IP using the above query. Literally takes less than a hundredth of a second to get a result and it's quite accurate. We have one website on a dedicated server, quite low traffic. But as with all servers I have ever checked, this one is hit daily by hackers' robots, checking email accounts, FTP accounts etc. And just about every web server I've ever worked on is compromised sooner or later. In our case, 99.99% of traffic from Asian countries has criminal intent attached to it.
We'd like this to run via iptables so that all ports are covered, not just HTTP for example by using directives in say .htaccess.
Do you think ipset would still be faster and more efficient?

Answer 1

It would be far too slow to launch perl for every matching packet. The right tool for this sort of thing is ipset, and there is much more information and documentation available on the ipset man page.
In CentOS you can install it with yum. Naturally, all of these commands and the script need to run as root:
# yum install ipset
Next install the kernel modules (you'll want this to happen at boot as well):
# modprobe -v ipset ip_set_hash_netport
And then use a script like the following to populate an ipset and block IP's from its ranges using iptables:
#!/usr/bin/env perl
use strict;
use warnings;
use DBI;
my $dbh = DBI->connect('... your DSN ...',...);
# I have no knowledge of your schema, but if you can pull the
# address range in the form: AA.BB.CC.DD/NN
my $ranges = $dbh->selectcol_arrayref(
q{SELECT cidr FROM your_table WHERE country_code IN ('CN',...)});
`ipset create geoblock hash:netport`;
for (#$ranges) {
# to match on port 80:
`ipset add geoblock $_,80`;
}
`iptables -I INPUT -m set --set geoblock src -j DROP`;
If you would like to block all ports rather than just 80, use the ip_set_hash_net module instead of ip_set_hash_netport, change hash:netport to hash:net, and remove ,80 from the ipset command.