Nftables geoip script

Python script that generates .nft files with mappings between IP addresses
and its geolocation, so you can include them inside your rules.

Requirements

Minimum python version: 3.9

Package used that are not present in the Python Standard Library

• requests

Usage example

To generate ipv4 and ipv6 mappings, download geoip data from db-ip.com
saving the output in the current folder

./nft_geoip.py --file-location location.csv --download

Giving the following output

drwxr-xr-x 2 foobar foobar 4,0K ene  4 19:38 .
drwxr-xr-x 5 foobar foobar 4,0K ene  4 19:38 ..
-rw-r--r-- 1 foobar foobar  22M ene  4 19:38 dbip.csv
-rw-r--r-- 1 foobar foobar  956 ene  4 19:38 geoip-def-africa.nft
-rw-r--r-- 1 foobar foobar 8,3K ene  4 19:38 geoip-def-all.nft
-rw-r--r-- 1 foobar foobar  902 ene  4 19:38 geoip-def-americas.nft
-rw-r--r-- 1 foobar foobar   15 ene  4 19:38 geoip-def-antarctica.nft
-rw-r--r-- 1 foobar foobar  808 ene  4 19:38 geoip-def-asia.nft
-rw-r--r-- 1 foobar foobar  810 ene  4 19:38 geoip-def-europe.nft
-rw-r--r-- 1 foobar foobar  461 ene  4 19:38 geoip-def-oceania.nft
-rw-r--r-- 1 foobar foobar 8,8M ene  4 19:38 geoip-ipv4.nft
-rw-r--r-- 1 foobar foobar  16M ene  4 19:38 geoip-ipv6.nft

• geoip-def-all defines variables for each country (2-char iso name)
  in location.csv assigning its iso numeric value (eg. Canada, define $CA = 124)
• geoip-ipv4.nft defines geoip4 map (@geoip4)
• geoip-ipv6.nft defines geoip6 map (@geoip6)

Creating a country filtered subset for geoip-*.nft files

If you don’t want the whole geoip map (including all countries) you can filter
by country using the -c/--country-filter parameter. This parameter enables
the creation of the additional files:

• geoip-ipv4-interesting.nft
• geoip-ipv6-interesting.nft

These files will contain nft maps with addresses related to the specified
countries only.

For example, to generate a Spanish, French and Portuguese only subset:

./nft_geoip.py --download -c es,fr,pt
...
Found countries:  {'france': 'fr', 'spain': 'es'}
Writing interesting countries file...
Done!

Marking packets to its corresponding country

Most importantly, using the maps you mark ipv4 and ipv6 packets with

meta mark set ip saddr map @geoip4
meta mark set ip saddr map @geoip6

You can mark output and input packets adding a chain with the
lowest priority among all of other chains in your table.

Marking output packets by destination

chain geoip-mark-output {
	type filter hook output priority -1; policy accept;

	meta mark set ip daddr map @geoip4
	meta mark set ip6 daddr map @geoip6
}

Marking input packet by origin

chain geoip-mark-input {
	type filter hook input priority -1; policy accept;

	meta mark set ip saddr map @geoip4
	meta mark set ip saddr map @geoip6
}

Example: Counting incoming Spanish traffic

Create a file, geoip.nft (it will be at /etc/geoip.nft for this example).

#!/usr/sbin/nft -f

table inet geoip {
	include "geoip-def-all.nft"
	include "geoip-ipv4.nft"
	include "geoip-ipv6.nft"

	chain geoip-mark-input {
		type filter hook input priority -1; policy accept;

		meta mark set ip saddr map @geoip4
		meta mark set ip6 saddr map @geoip6
	}

	chain input {
		type filter hook input priority 0; policy accept;

		meta mark $ES counter
	}
}

NOTE: If you plan on using both ipv4 and ipv6 sets you need to use the inet prefix for the table type.

Then run nft -f /etc/geoip.nft to add it to your firewall.

You can also make the new table, chain and rules permanent by editing your distro specific file
(/etc/nftables.conf for Arch Linux or Debian) by including geoip.nft. This file is usually run at boot.

#!/usr/sbin/nft -f

flush ruleset
include "/etc/geoip.nft"

# your ruleset...

...

When updating the geoip maps (geoip-ipv4 and/or geoip-ipv6), you will need to
reload /etc/geoip.nft so new geoip maps are included again and old ones dropped:

nft delete table geoip
nft -f /etc/geoip.nft

Example: Counting incoming Spanish traffic (using smaller geoip map files)

Use the -c/--country-filter parameter to generate the additional files:

• geoip-ipv4-interesting.nft
• geoip-ipv6-interesting.nft

For this example the command might look like this (assuming dbip.csv is not
present):

$ ./nft_geoip --download -c es

Create a file, geoip.nft (it will be at /etc/geoip.nft for this example)
and use the “interesting” files not the whole geoip maps.

#!/usr/sbin/nft -f

table inet geoip {
	include "geoip-def-all.nft"
	include "geoip-ipv4-interesting.nft"
	include "geoip-ipv6-interesting.nft"

	chain geoip-mark-input {
		type filter hook input priority -1; policy accept;

		meta mark set ip saddr map @geoip4
		meta mark set ip6 saddr map @geoip6
	}

	chain input {
		type filter hook input priority 0; policy accept;

		meta mark $ES counter
	}
}

NOTE: You can replace geoip-def-all.nft by geoip-def-europe.nft, or
just copy the “define ES = …” line into your nft file.

Caveats

It is not possible to use the country definitions inside an interactive
nft shell.

So, although maps are defined, country definitions do not persist.
You will need to define those geoip rules inside your ruleset definition
files. Like in the example above.

You will need ~300MB of free memory to run the script and also to load
the full (all) ipv4 and ipv6 maps.

It’s been reported that low memory machines, (eg. GCP f1-micro) are not
enough and the scripts ends up killed by the OOM-killer.

This will be fixed in #1.