MaxMind GeoIP dlfunc for Exim

This is an IPv4 and IPv6 capable GeoIP dlfunc library for Exim. It implements an interface between Exim access control lists and MaxMind's GeoIP database. This can be useful for greylisting or scoring IP addresses of SMTP senders according to the country code of the sender's IP address.

• Download: https://dist.epipe.com/exim/
• GitHub: https://github.com/snabb/exim-geoipv6-dlfunc
• Author: Janne Snabb, snabb at epipe.com
• License: LGPL version 2.1 or later

Installation

The build system is based on GNU autoconf, automake and libtool. That makes the size of this software tarball enormously big, but it is supposedly the best somewhat portable way for creating shared libraries without getting a headache from thinking about compiler and linker flags.

Exim's local_scan.h header file is needed for compilation. Also MaxMind's GeoIP C API library is needed, version 1.4.7 or newer. On Debian and Ubuntu the dependencies are available in exim4-dev and libgeoip-dev packages:

apt-get install exim4-dev libgeoip-dev

Alternatively you may point the include path in CPPFLAGS to some other directory where Exim's local_scan.h is located (such as Exim build directory).

RHEL/CentOS/etc. have the GeoIP library in GeoIP-devel package.

You may want to alter some settings at the start of exim-geoipv6-dlfunc.c to suit your local needs.

The following command can be used to configure the library on Debian and Ubuntu Linux:

CPPFLAGS="-I/usr/include/exim4" ./configure --libdir=/usr/local/lib/exim4/

On systems which have the GeoIP library in /usr/local, such as FreeBSD, you can specify something like the following:

CPPFLAGS="-I/usr/local/include -I/exim/build/directory" \
LDFLAGS="-L/usr/local/lib" \
./configure --libdir=/usr/local/lib/exim4/

(The previous command should be all on one single line if entered without the backslashes.)

Compilation and installation should be as simple as the following if the configure script was run with correct parameters and dependencies are available:

make
make install

Usage

Exim must be compiled with the "dlfunc" feature enabled (EXPAND_DLFUNC=yes).

Also Exim must be compiled with -export-dynamic in EXTRALIBS to make Exim's local_scan API available.

On Debian and Ubuntu you need to use exim4-daemon-heavy package. exim4-daemon-light package will not work.

You need to have MaxMind's GeoIP database available in the correct location. IPv4 and IPv6 databases are in separate files. The Lite version of the database is available free of charge at MaxMind web site. On Debian and Ubuntu it is available in geoip-database or geoip-database-contrib package:

apt-get install geoip-database-contrib

You can add something such as the following in Exim connect ACL:

warn    set acl_c_geoip_country_code = \
                ${dlfunc{/usr/local/lib/exim4/exim-geoipv6-dlfunc.so}\
                        {geoip_country_code}{$sender_host_address}}

After that you can use $acl_c_geoip_country_code variable in ACL conditions, for example:

deny    condition = ${if inlist{$acl_c_geoip_country_code}{US:GB}}
        message = We do not accept messages from your country.

If you are using Exim version older than 4.77 you need to use "forany" instead of "inlist" if you want to match against a list of country codes:

warn    condition = ${if forany{US:GB}\
                {eq{$item}{$acl_c_geoip_country_code}}}
        set acl_c_ipscore = ${eval:$acl_c_ipscore+10}

You can also add something like the following in the DATA ACL to add a message header which indicates the country code of the connecting IP:

warn    condition = ${if def:acl_c_geoip_country_code}
        add_header = X-GeoIP: $acl_c_geoip_country_code

Working with development version

If you check out the development version from GitHub, you need to have GNU autotools, libtool, etc. installed.

To generate all the automatically created files you need to run the bootstrap script.