bionic (3) Mail::SpamAssassin::Plugin::ASN.3pm.gz
NAME
Mail::SpamAssassin::Plugin::ASN - SpamAssassin plugin to look up the Autonomous System Number (ASN) of
the connecting IP address.
SYNOPSIS
loadplugin Mail::SpamAssassin::Plugin::ASN
asn_lookup asn.routeviews.org _ASN_ _ASNCIDR_
add_header all ASN _ASN_ _ASNCIDR_
header TEST_AS1234 X-ASN =~ /^1234$/
DESCRIPTION
This plugin uses DNS lookups to the services of an external DNS zone such as at
"http://www.routeviews.org/" to do the actual work. Please make sure that your use of the plugin does not
overload their infrastructure - this generally means that you should not use this plugin in a high-volume
environment or that you should use a local mirror of the zone (see "ftp://ftp.routeviews.org/dnszones/").
Other similar zones may also be used.
TEMPLATE TAGS
This plugin allows you to create template tags containing the connecting IP's AS number and route info
for that AS number.
The default config will add a header field that looks like this:
X-Spam-ASN: AS24940 213.239.192.0/18
where "24940" is the ASN and "213.239.192.0/18" is the route announced by that ASN where the connecting
IP address came from. If the AS announces multiple networks (more/less specific), they will all be added
to the "_ASNCIDR_" tag, separated by spaces, eg:
X-Spam-ASN: AS1680 89.138.0.0/15 89.139.0.0/16
Note that the literal "AS" before the ASN in the _ASN_ tag is configurable through the asn_prefix
directive and may be set to an empty string.
CONFIGURATION
The standard ruleset contains a configuration that will add a header field containing ASN data to scanned
messages. The bayes tokenizer will use the added header field for bayes calculations, and thus affect
which BAYES_* rule will trigger for a particular message.
Note that in most cases you should not score on the ASN data directly. Bayes learning will probably
trigger on the _ASNCIDR_ tag, but probably not very well on the _ASN_ tag alone.
SEE ALSO
http://www.routeviews.org/ - all data regarding routing, ASNs, etc.... http://issues.apache.org/SpamAssassin/show_bug.cgi?id=4770 - SpamAssassin Issue #4770 concerning this plugin
STATUS
No in-depth analysis of the usefulness of bayes tokenization of ASN data has been performed.
ADMINISTRATOR SETTINGS
asn_lookup asn-zone.example.com [ _ASNTAG_ _ASNCIDRTAG_ ]
Use this to lookup the ASN info in the specified zone for the first external IP address and add the
AS number to the first specified tag and routing info to the second specified tag.
If no tags are specified the AS number will be added to the _ASN_ tag and the routing info will be
added to the _ASNCIDR_ tag. You must specify either none or both of the tag names. Tag names must
start and end with an underscore.
If two or more asn_lookups use the same set of template tags, the results of their lookups will be
appended to each other in the template tag values in no particular order. Duplicate results will be
omitted when combining results. In a similar fashion, you can also use the same template tag for
both the AS number tag and the routing info tag.
Examples:
asn_lookup asn.routeviews.org
asn_lookup asn.routeviews.org _ASN_ _ASNCIDR_
asn_lookup myview.example.com _MYASN_ _MYASNCIDR_
asn_lookup asn.routeviews.org _COMBINEDASN_ _COMBINEDASNCIDR_
asn_lookup myview.example.com _COMBINEDASN_ _COMBINEDASNCIDR_
asn_lookup in1tag.example.net _ASNDATA_ _ASNDATA_
clear_asn_lookups
Removes any previously declared asn_lookup entries from a list of queries.
asn_prefix 'prefix_string' (default: 'AS')
The string specified in the argument is prepended to each ASN when storing it as a tag. This prefix
is rather redundant, but its default value 'AS' is kept for backward compatibility with versions of
SpamAssassin earlier than 3.4.0. A sensible setting is an empty string. The argument may be (but need
not be) enclosed in single or double quotes for clarity.