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ipset-blacklist

A set of shell scripts which use ipset and iptables to ban a large number of IP addresses published in IP blacklists. ipset uses a hashtable to store/fetch IP addresses and thus the IP lookup is a lot (!) faster than thousands of sequentially parsed iptables ban rules. However, the limit of an ipset list is 2^16 entries.

Note: Updating the blacklists takes a long time (8m 20s on a TPLink TL-WDR3600), and running at a low priority (with nice and ionice) is recommended to avoid impacting packet routing & firewall performance.

Quick start for OpenWRT

  1. Copy the scripts to a temporary directory on your OpenWRT router
  2. Run sh install.sh

iptables filter rule

ipset create blacklist_net hash:net
ipset create blacklist_ip hash:ip
iptables -I INPUT -m set --match-set blacklist_net src -j DROP
iptables -I INPUT -m set --match-set blacklist_ip src -j DROP

Make sure to run this snippet in your firewall script. If you don't, the ipset blacklist and the iptables rule to ban the blacklisted ip addresses will be missing!

Cron job

In order to auto-update the blacklist, copy the following code into /etc/cron.d/update-blacklist. Don't update the list too often or some blacklist providers will ban your IP address. Once a day should be OK though.

33 23 * * *      /bin/nice /usr/local/bin/update-blacklist.sh > /tmp/update-blacklist.log 2>&1

Check for dropped packets

Using iptables, you can check how many packets got dropped using the blacklist:

drfalken@wopr:~# iptables -L -vn
Chain INPUT (policy DROP 3064 packets, 177K bytes)
 pkts bytes target     prot opt in     out     source               destination
   43  2498 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0            match-set blacklist src