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Block countries using IPtables and IPDeny.com

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Certain server setups do not require access for all countries or just want to block certain countries since they are know for their malicious activity.

One simple (not full bullet-proof) way of doing this, is by setting up block rules on firewall level, which can be achieved on Linux servers with iptables and zone files of https://www.ipdeny.com/. These zone files contain the network ranges assigned to a specific country.

The network ranges are fed to a tool called ipset, which sets up of hash map that can be easily used within iptables rules.

On Debian/Ubuntu systems, ipset can be installed with the apt command:

apt install ipset

Next, create an iptables chain called “blocked_countries“, to which we will add rules afterwards. Add this chain to the beginning of the INPUT and FORWARD chain, to have early blocking in your ruleset.

iptables -N blocked_countries
iptables -I INPUT -j blocked_countries -m comment --comment "Blocked countries"
iptables -I FORWARD -j blocked_countries -m comment --comment "Blocked countries"

Finally, create a shell script which will download the required zone files from https://ipdeny.com/ and which feeds them to ipset. The example script will try to block the countries China, Russia and Belarus:

#!/bin/bash

COUNTRIES=('cn' 'ru' 'by')

for COUNTRY in "${COUNTRIES[@]}"; do
    ipset create "countries_${COUNTRY}" hash:net
done

iptables -v -F blocked_countries

for i in "${COUNTRIES[@]}"; do
    echo "Ban IP of country ${i}"
    ipset flush "countries_${i}"


    for IP in $(wget -O - https://www.ipdeny.com/ipblocks/data/countries/${i}.zone)
    do
        ipset add "countries_${i}" $IP
    done
    iptables -I blocked_countries   -m set --match-set "countries_${i}" src  -j LOGDROP -m comment   --comment "Block .${i}"
done


You can check the blocked_countries chain if packets are being blocked by your new rules:

iptables -v -n -L blocked_countries 
# Warning: iptables-legacy tables present, use iptables-legacy to see them
Chain blocked_countries (2 references)
 pkts bytes target     prot opt in     out     source               destination         
    2   104 LOGDROP    all  --  *      *       0.0.0.0/0            0.0.0.0/0            match-set countries_by src /* Block .by */
 2182  155K LOGDROP    all  --  *      *       0.0.0.0/0            0.0.0.0/0            match-set countries_ru src /* Block .ru */
  344 21370 LOGDROP    all  --  *      *       0.0.0.0/0            0.0.0.0/0            match-set countries_cn src /* Block .cn */

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