Block Google requests to 16k using pf firewall
- by atmosx
I'd like to block access to Google search using PF after the threshold of 17500 requests (connection established) in 24h, from a host running FreeBSD 9.
What I came up with, after reading pf-faq is this rule:
pass out on $net proto tcp from any to 'www.google.com' port www flags S/SA keep state (max-src-conn 200, max-src-conn-rate 17500/86400)
NOTE: 86400 are 24h in seconds.
The rule should work, but PF is smart enough to know that www.google.com resolves in 5 different IPs. So my pfctl -sr output gives me this:
pass out on vte0 inet proto tcp from any to 173.194.44.81 port = http flags S/SA keep state (source-track rule, max-src-conn 200, max-src-conn-rate 17500/86400, src.track 86400)
pass out on vte0 inet proto tcp from any to 173.194.44.82 port = http flags S/SA keep state (source-track rule, max-src-conn 200, max-src-conn-rate 17500/86400, src.track 86400)
pass out on vte0 inet proto tcp from any to 173.194.44.83 port = http flags S/SA keep state (source-track rule, max-src-conn 200, max-src-conn-rate 17500/86400, src.track 86400)
pass out on vte0 inet proto tcp from any to 173.194.44.80 port = http flags S/SA keep state (source-track rule, max-src-conn 200, max-src-conn-rate 17500/86400, src.track 86400)
pass out on vte0 inet proto tcp from any to 173.194.44.84 port = http flags S/SA keep state (source-track rule, max-src-conn 200, max-src-conn-rate 17500/86400, src.track 86400)
PF creates 5 different rules, 1 for each IP that Google resolves. However I have the sense - without being 100% sure, I didn't had the chance to test it - that the number 17500/86400 applies for each IP. If that's the case - please confirm - then it's not what I want.
In pf-faq there's another option called source-track-global:
source-track
This option enables the tracking of number of states created per source IP
address. This option has two formats:
+ source-track rule - The maximum number of states created by this rule
is limited by the rule's max-src-nodes and max-src-states options.
Only state entries created by this particular rule count toward the
rule's limits.
+ source-track global - The number of states created by all rules that
use this option is limited. Each rule can specify different
max-src-nodes and max-src-states options, however state entries
created by any participating rule count towards each individual rule's
limits.
The total number of source IP addresses tracked globally can be controlled
via the src-nodes runtime option.
I tried to apply source-track-global in the above rule without success. How can I use this option in order to achieve my goal?
Any thoughts or comments are more than welcome since I'm an amateur and don't fully understand PF yet.
Thanks
