On Jun 5, 2012, at 12:38 AM, Matt Simerson wrote: > On Jun 4, 2012, at 2:56 PM, Stevan Bajić wrote: > >> - If it is important to you then doing something like GeoIP lookups could be >> interesting for certain users (either to block or whitelist based on >> continent, region, country). I usually use that data to compute the distance >> between me and the sender. The bigger the distance is the more likely it is >> spam (search for SNARE if you need a research paper on that topic).
> SNARE: > http://smartech.gatech.edu/bitstream/handle/1853/25135/GT-CSE-08-02.pdf?sequence=1 > > Their findings echo what I see in my logs. Windows PCs sending email to my > server from outside my country have a 95% chance of being spam. The problem I > see with SNARE is the way-too-high 7% false positive rate. It's useful > information, but not something that can be used to reject the connection. On > its own. But you can use the data to make the sender jump through extra hoops. I'm not sure how useful it will be, but the geoip plugin now calculates geodesic distance. Matt https://github.com/smtpd/qpsmtpd/pull/28 NAME geoip - provide geographic information about mail senders. SYNOPSIS Use MaxMind's GeoIP databases and the Geo::IP perl module to report geographic information about incoming connections. DESCRIPTION This plugin saves geographic information in the following connection notes: geoip_country - 2 char country code geoip_country_name - full english name of country geoip_continent - 2 char continent code geoip_distance - distance in kilometers And adds entries like this to your logs: (connect) ident::geoip: US, United States, NA, 1319 km (connect) ident::geoip: IN, India, AS, 13862 km (connect) ident::geoip: fail: no results (connect) ident::geoip: CA, Canada, NA, 2464 km (connect) ident::geoip: US, United States, NA, 2318 km (connect) ident::geoip: PK, Pakistan, AS, 12578 km (connect) ident::geoip: TJ, Tajikistan, AS, 11965 km (connect) ident::geoip: AT, Austria, EU, 8745 km (connect) ident::geoip: IR, Iran, Islamic Republic of, AS, 12180 km (connect) ident::geoip: BY, Belarus, EU, 9030 km (connect) ident::geoip: CN, China, AS, 11254 km (connect) ident::geoip: PA, Panama, NA, 3163 km Calculating the distance has three prerequsites: 1. The MaxMind city database (free or subscription) 2. The Math::Complex perl module 3. The IP address of this mail server (see CONFIG) Other plugins can utilize the geographic notes to alter the connection, reject, greylist, etc. CONFIG The following options can be appended in this plugins config/plugins entry. distance <IP Address> Enables geodesic distance calculation. Will calculate the distance "as the crow flies" from the remote mail server. Accepts a single argument, the IP address to calculate the distance from. This will typically be the public IP of your mail server. ident/geoip [ distance 192.0.1.5 ] Default: none. (no distance calculations) db_dir </path/to/GeoIP> The path to the GeoIP database directory. ident/geoip [ db_dir /etc/GeoIP ] Default: /usr/local/share/GeoIP LIMITATIONS The distance calculations are more concerned with being fast than accurate. The MaxMind location data is collected from whois and is of limited accuracy. MaxMind offers more accurate data for a fee. For distance calculations, the earth is considered a perfect sphere. In reality, it is not. Accuracy should be within 1%. This plugin does not update the GeoIP databases. You may want to. CHANGES 2012-06 - Matt Simerson - added GeoIP City support, continent, distance 2012-05 - Matt Simerson - added geoip_country_name note, added tests SEE ALSO MaxMind: http://www.maxmind.com/ Databases: http://geolite.maxmind.com/download/geoip/database It may become worth adding support for Geo::IPfree, which uses another data source: http://software77.net/geo-ip/ ACKNOWLEDGEMENTS Stevan Bajic, the DSPAM author, who suggested SNARE, which describes using geodesic distance to determine spam probability. The research paper on SNARE can be found here: http://smartech.gatech.edu/bitstream/handle/1853/25135/GT-CSE-08-02.pdf ````````````````````````````````````````````````````````````````````````` Matt Simerson http://matt.simerson.net/ Systems Engineer http://www.tnpi.net/ Mail::Toaster - http://mail-toaster.org/ NicTool - http://www.nictool.com/ `````````````````````````````````````````````````````````````````````````
