GeoLocation

During the process of creating policy scripts the need may arise to find the geographic location for an IP address. Bro has support for the GeoIP library at the policy script level beginning with release 1.3 to account for this need. To use this functionality, you need to first install the libGeoIP software, and then install the GeoLite city database before building Bro.

Contents

• GeoLocation
  • Install libGeoIP
  • GeoIPLite Database Installation
  • Testing
  • Usage
  • Example

Install libGeoIP

Before building Bro, you need to install libGeoIP.

• FreeBSD:

  sudo pkg install GeoIP
  

• RPM/RedHat-based Linux:

  sudo yum install GeoIP-devel
  

• DEB/Debian-based Linux:

  sudo apt-get install libgeoip-dev
  

• Mac OS X:

  You need to install from your preferred package management system (e.g. MacPorts, Fink, or Homebrew). The name of the package that you need may be libgeoip, geoip, or geoip-dev, depending on which package management system you are using.

GeoIPLite Database Installation

A country database for GeoIPLite is included when you do the C API install, but for Bro, we are using the city database which includes cities and regions in addition to countries.

Download the GeoLite city binary database:

wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz
gunzip GeoLiteCity.dat.gz

Next, the file needs to be renamed and put in the GeoIP database directory. This directory should 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 GeoLiteCity.dat <path_to_database_dir>/GeoIPCity.dat

Note that there is a separate database for IPv6 addresses, which can also be installed if you want GeoIP functionality for IPv6.

Testing

Before using the GeoIP functionality, it is a good idea to verify that everything is setup correctly. After installing libGeoIP 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 City database”, then you may need to either rename or move your GeoIP city database file (the error message should give you the full pathname of the database file that Bro is looking for).

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 libGeoIP. Normally, if libGeoIP 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 libGeoIP 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);
  }
}