GeoLocation

During the process of creating policy scripts the need may arise to find the geographic location for an IP address. Bro had support for the GeoIP library at the policy script level from release 1.3 to 2.5.x to account for this need. Starting with release 2.6, GeoIP support requires libmaxminddb. To use this functionality, you need to first install the libmaxminddb software, and then install the GeoLite2 city database before building Bro.

Contents

• GeoLocation
  • Install libmaxminddb
  • GeoLite2-City Database Installation
  • Testing
  • Usage
  • Example

Install libmaxminddb

Before building Bro, you need to install libmaxminddb.

• RPM/RedHat-based Linux:

  sudo yum install libmaxminddb-devel
  

• DEB/Debian-based Linux:

  sudo apt-get install libmaxminddb-dev
  

• FreeBSD:

  sudo pkg install libmaxminddb
  

• Mac OS X:

  You need to install from your preferred package management system (e.g. Homebrew, MacPorts, or Fink). For Homebrew, the name of the package that you need is libmaxminddb.

GeoLite2-City Database Installation

Bro can use the city or country database. The city database includes cities and regions in addition to countries.

Download the GeoLite2 city binary database:

wget http://geolite.maxmind.com/download/geoip/database/GeoLite2-City.tar.gz
tar zxf GeoLite2-City.tar.gz

Next, the file “GeoLite2-City_YYYYMMDD/GeoLite2-City.mmdb” needs to be moved to the GeoIP database directory. This directory might already exist and will vary depending on which platform and package you are using. For FreeBSD, use /usr/local/share/GeoIP. For Linux, use /usr/share/GeoIP or /var/lib/GeoIP (choose whichever one already exists).

mv <extracted subdir>/GeoLite2-City.mmdb <path_to_database_dir>/GeoLite2-City.mmdb

Testing

Before using the GeoIP functionality, it is a good idea to verify that everything is setup correctly. After installing libmaxminddb and the GeoIP city database, and building Bro, you can quickly check if the GeoIP functionality works by running a command like this:

bro -e "print lookup_location(8.8.8.8);"

If you see an error message similar to “Failed to open GeoIP location database”, then you may need to either rename or move your GeoIP location database file. If the mmdb_dir value is set to a directory pathname (it is not set by default), then Bro looks for location database files in that directory. If none are found or if mmdb_dir is not set, then Bro looks for location database files in the following order:

• /usr/share/GeoIP/GeoLite2-City.mmdb
• /var/lib/GeoIP/GeoLite2-City.mmdb
• /usr/local/share/GeoIP/GeoLite2-City.mmdb
• /usr/local/var/GeoIP/GeoLite2-City.mmdb
• /usr/share/GeoIP/GeoLite2-Country.mmdb
• /var/lib/GeoIP/GeoLite2-Country.mmdb
• /usr/local/share/GeoIP/GeoLite2-Country.mmdb
• /usr/local/var/GeoIP/GeoLite2-Country.mmdb

If you see an error message similar to “Bro was not configured for GeoIP support”, then you need to rebuild Bro and make sure it is linked against libmaxminddb. Normally, if libmaxminddb is installed correctly then it should automatically be found when building Bro. If this doesn’t happen, then you may need to specify the path to the libmaxminddb installation (e.g. ./configure --with-geoip=<path>).

Usage

There is a built-in function that provides the GeoIP functionality:

function lookup_location(a:addr): geo_location

The return value of the lookup_location function is a record type called geo_location, and it consists of several fields containing the country, region, city, latitude, and longitude of the specified IP address. Since one or more fields in this record will be uninitialized for some IP addresses (for example, the country and region of an IP address might be known, but the city could be unknown), a field should be checked if it has a value before trying to access the value.

Example

To show every ftp connection from hosts in Ohio, this is now very easy:

event ftp_reply(c: connection, code: count, msg: string, cont_resp: bool)
{
  local client = c$id$orig_h;
  local loc = lookup_location(client);

  if (loc?$region && loc$region == "OH" && loc$country_code == "US")
  {
    local city = loc?$city ? loc$city : "<unknown>";

    print fmt("FTP Connection from:%s (%s,%s,%s)", client, city,
      loc$region, loc$country_code);
  }
}