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_
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.
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.