Allow SSH access based on Country using GeoIP

1. Install packages

   $ sudo apt install geoip-bin geoip-database
   

2. Create script

   $ sudo vi /usr/local/bin/sshfilter.sh
   

   
   #!/bin/bash
   
   ALLOWED_COUNTRIES="KR US GB NZ"
   ALLOWED_IP="192.168 127.0.0"
   
   [[ "`echo $1 | grep ':'`" != "" ]] && SUFFIX="6"
   if [[ $ALLOWED_IP =~ ${1:0:7} ]]; then
    logger -p authpriv.notice "SSH ALLOWED $1 LOCALDOMAIN"
    exit 0
   fi
   
   GEORESULT=`/usr/bin/geoiplookup${SUFFIX} "$1"`
   COUNTRY=`echo $GEORESULT | cut -d : -f 2 | xargs | head -1`
   COUNTRYCODE=`echo $COUNTRY | cut -d , -f 1 | xargs`
   [[ $ALLOWED_COUNTRIES =~ $COUNTRYCODE ]] && RESPONSE="ALLOWED" || RESPONSE="DENIED"
   logger -p authpriv.notice "SSH $RESPONSE $1 $COUNTRY"
   [[ $RESPONSE == "ALLOWED" ]] && exit 0 || exit 1
   

3. edit /etc/hosts.allow and /etc/hosts.deny

   # /etc/hosts.allow
   sshd: ALL: /usr/local/bin/sshfilter.sh %a
   

   # /etc/hosts.deny
   sshd: ALL