SSH GeoIP Filtering script using MaxMind GeoIP2 & GeoLite2 via mmdblookup.

The script was orignally inspired by authors in found in Acknowledgements, with modifications made by me to use the latest supported mmdblookup utility from MaxMind to interact with the GeoIP2/GeoLite2 database instead of the outdated geoiplookup/geoiplookup6 utility that only works for the GeoIP Legacy database.

The mmdblookup supports both IPv4 and IPv6 addresses, and different mmdb database files such as GeoLite2-ASN.mmdb, GeoLite2-City.mmdb, GeoLite2-Country.mmdb etc depending on your subscription with MaxMind, but the free GeoLite2 would be more than enough for GeoIP filtering.

The script currently uses the GeoLite2-Country.mmdb file to do two-letter country code lookup, refered to as ISO 3166-1 alpha-2. It could be changed depending on your needs by editing the ALLOW_COUNTRIES line in the script.

To update your GeoIP database you need an free MaxMind License Key - register an account with MaxMind, see MaxMind's docs on geoipupdate.

You would also need to install the latest geoipupdate version, you can find the lastest version & installation instruction on MaxMind's geoipupdate repo.

From the docs, you will also be able to follow the instruction to download a sample configuration file to be put at /etc/GeoIP.conf.

The /etc/GeoIP.conf should look like this:

# GeoIP.conf file for `geoipupdate` program, for versions >= 3.1.1.
# Used to update GeoIP databases from https://www.maxmind.com.
# For more information about this config file, visit the docs at
# https://dev.maxmind.com/geoip/updating-databases.

# `AccountID` is from your MaxMind account.
AccountID YOUR_ACCOUNT_ID_HERE

# Replace YOUR_LICENSE_KEY_HERE with an active license key associated
# with your MaxMind account.
LicenseKey YOUR_LICENSE_KEY_HERE

# `EditionIDs` is from your MaxMind account.
EditionIDs GeoLite2-ASN GeoLite2-City GeoLite2-Country

After which you can follow the instructions below to get started in installing the script.

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. Assuming that you have already installed the required packages and have the GeoIP database setup.

All commands are to be run as root or with sudo.

1. Install required packages:

   sudo apt update
   sudo apt install libmaxminddb0 libmaxminddb-dev mmdb-bin geoipupdate

• libmaxminddb0 libmaxminddb-dev – MaxMind Geolocation database libraries
• mmdb-bin – binary. Program to call from the command line. Use this command to geolocate IP manually.
• geoipupdate – package that assists in configuring and updating GeoIP2 / GeoLite2.

2. Download the latest release:

   curl -s https://api.github.com/repos/xKhronoz/SSH-GeoIP-Filter/releases/latest \
   | grep "tarball_url" \
   | cut -d '"' -f 4 \
   | wget -O xKhronoz-SSH-GeoIP-Filter-latest.tar.gz -i - \
   && mkdir -p xKhronoz-SSH-GeoIP-Filter-latest \
   && tar -xzf xKhronoz-SSH-GeoIP-Filter-latest.tar.gz -C xKhronoz-SSH-GeoIP-Filter-latest --strip-components=1 \
   && rm xKhronoz-SSH-GeoIP-Filter-latest.tar.gz

3. Copy the script to /usr/local/bin, and add execute permissions:

   (sshd runs as root, so it needs to be able to execute the script)

   cd xKhronoz-SSH-GeoIP-Filter
   sudo cp ssh-geoip-filter.sh /usr/local/bin/
   sudo chmod +x /usr/local/bin/ssh-geoip-filter.sh

4. Edit line 5 in sshd-geoip-filter.sh to countries that you want to allow ssh from, separated by space (if more than 1), in uppercase ISO country codes (e.g. SG for Singapore).

   sudo nano /usr/local/bin/ssh-geoip-filter.sh

   4: # UPPERCASE space-separated ISO country codes to ACCEPT
   5: ALLOW_COUNTRIES="SG"

5. Update /etc/hosts.allow & /etc/hosts.deny

   sudo nano /etc/hosts.deny
   # Add in this line:
   sshd: ALL
   
   sudo nano /etc/hosts.allow
   # Add in this line:
   sshd: ALL: aclexec /usr/local/bin/ssh-geoip-filter.sh %a

• Using aclexec in hosts.allow will allow the sshd service to take into account the exit code and abort connection attempts.

6. Setup Crontab to run geoipupdate periodically:

   # Setup crontab as sudo
   sudo crontab -e

   Add in the lines below, change the timezone and schedule according to your preference (Use Crontab Guru to set the schedule):

   # Disable mailing (Optional, remove MAILTO="" to enable mailing)
   MAILTO=""
   
   # CRON TIMEZONE (Optional, change to your preferred timezone)
   CRON_TZ=Asia/Singapore
   
   # Update Maxmind GeoIP2 Database at 4am every thursday & saturday, logs to a file
   0 4 * * 4,6 /usr/bin/geoipupdate -v >> /var/log/cron.log 2>&1

Tested on Ubuntu 22.04 and Debian 11, should work on other similar linux systems running sshd.

• Create a installation script to automate the installation process.
• Add support to edit the 'ALLOW_COUNTRIES' by user in installation script.

• CristianCantoro's ssh-geoip-filter
• Ralph Slooten at axllent.org
• Ryan Harg at blog.reinhard.codes