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Mail::SpamAssassin::Plugin::URIDNSBL(3) |
User Contributed Perl Documentation |
Mail::SpamAssassin::Plugin::URIDNSBL(3) |
URIDNSBL - look up URLs against DNS blocklists
loadplugin Mail::SpamAssassin::Plugin::URIDNSBL
uridnsbl URIBL_SBLXBL sbl-xbl.spamhaus.org. TXT
This works by analysing message text and HTML for URLs, extracting host names
from those, then querying various DNS blocklists for either: IP addresses of
these hosts (uridnsbl,a) or their nameservers (uridnsbl,ns), or domain names
of these hosts (urirhsbl), or domain names of their nameservers (urinsrhsbl,
urifullnsrhsbl).
- skip_uribl_checks ( 0 | 1 ) (default: 0)
- Turning on the skip_uribl_checks setting will disable the URIDNSBL plugin.
By default, SpamAssassin will run URI DNSBL checks. Individual
URI blocklists may be disabled selectively by setting a score of a
corresponding rule to 0 or through the uridnsbl_skip_domain
parameter.
See also a related configuration parameter skip_rbl_checks,
which controls the DNSEval plugin (documented in the Conf man page).
- uridnsbl_skip_domain domain1 domain2 ...
- Specify a domain, or a number of domains, which should be skipped for the
URIBL checks. This is very useful to specify very common domains which are
not going to be listed in URIBLs.
In addition to trimmed domain, the full hostname is also
checked from the list.
- clear_uridnsbl_skip_domain [domain1 domain2 ...]
- If no argument is given, then clears the entire list of domains declared
by uridnsbl_skip_domain configuration directives so far. Any
subsequent uridnsbl_skip_domain directives will start creating a
new list of skip domains.
When given a list of domains as arguments, only the specified
domains are removed from the list of skipped domains.
- uridnsbl NAME_OF_RULE dnsbl_zone lookuptype
- Specify a lookup. "NAME_OF_RULE" is the
name of the rule to be used,
"dnsbl_zone" is the zone to look up IPs
in, and "lookuptype" is the type of
lookup (TXT or A). Note that you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
This works by collecting domain names from URLs and querying
DNS blocklists with an IP address of host names found in URLs or with IP
addresses of their name servers, according to tflags as follows.
If the corresponding body rule has a tflag 'a', the DNS
blocklist will be queried with an IP address of a host found in
URLs.
If the corresponding body rule has a tflag 'ns', DNS will be
queried for name servers (NS records) of a domain name found in URLs,
then these name server names will be resolved to their IP addresses,
which in turn will be sent to DNS blocklist.
Tflags directive may specify either 'a' or 'ns' or both flags.
In absence of any of these two flags, a default is a 'ns', which is
compatible with pre-3.4 versions of SpamAssassin.
The choice of tflags must correspond to the policy and
expected use of each DNS blocklist and is normally not a local decision.
As an example, a blocklist expecting queries resulting from an 'a' tflag
is a "black_a.txt" ( http://www.uribl.com/datasets.shtml
).
Example:
uridnsbl URIBL_SBLXBL sbl-xbl.spamhaus.org. TXT
body URIBL_SBLXBL eval:check_uridnsbl('URIBL_SBLXBL')
describe URIBL_SBLXBL Contains a URL listed in the SBL/XBL blocklist
tflags URIBL_SBLXBL net ns
- uridnssub NAME_OF_RULE dnsbl_zone lookuptype subtest
- Specify a DNSBL-style domain lookup with a sub-test.
"NAME_OF_RULE" is the name of the rule
to be used, "dnsbl_zone" is the zone to
look up IPs in, and "lookuptype" is the
type of lookup (TXT or A).
Tflags 'ns' and 'a' on a corresponding body rule are
recognized and have the same meaning as in the uridnsbl directive.
"subtest" is a sub-test to
run against the returned data. The sub-test may be in one of the
following forms: m, n1-n2, or n/m, where n,n1,n2,m can be any of:
decimal digits, 0x followed by up to 8 hexadecimal digits, or an IPv4
address in quad-dot form. The 'A' records (IPv4 dotted address) as
returned by DNSBLs lookups are converted into a numerical form (r) and
checked against the specified sub-test as follows: for a range n1-n2 the
following must be true: (r >= n1 && r <= n2); for a n/m
form the following must be true: (r & m) == (n & m); for a
single value in quad-dot form the following must be true: r == n; for a
single decimal or hex form the following must be true:
((r & n) != 0) && ((r & 0xff000000) == 0x7f000000), i.e.
within 127.0.0.0/8
Some typical examples of a sub-test are: 127.0.1.2,
127.0.1.20-127.0.1.39, 127.0.1.0/255.255.255.0, 0.0.0.16/0.0.0.16,
0x10/0x10, 16, 0x10 .
Note that, as with
"uridnsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
Example:
uridnssub URIBL_DNSBL_4 dnsbl.example.org. A 127.0.0.4
uridnssub URIBL_DNSBL_8 dnsbl.example.org. A 8
- urirhsbl NAME_OF_RULE rhsbl_zone lookuptype
- Specify a RHSBL-style domain lookup.
"NAME_OF_RULE" is the name of the rule
to be used, "rhsbl_zone" is the zone to
look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A). Note that you must also define a body-eval rule
calling "check_uridnsbl()" to use this.
An RHSBL zone is one where the domain name is looked up, as a
string; e.g. a URI using the domain
"foo.com" will cause a lookup of
"foo.com.uriblzone.net". Note that
hostnames are trimmed to the domain portion in the URIBL lookup, so the
domain "foo.bar.com" will look up
"bar.com.uriblzone.net", and
"foo.bar.co.uk" will look up
"bar.co.uk.uriblzone.net". Using tflag
"notrim" will force full hostname
lookup, but the specific uribl must support this method.
If an URI consists of an IP address instead of a hostname, the
IP address is looked up (using the standard reversed quads method) in
each "rhsbl_zone".
Example:
urirhsbl URIBL_RHSBL rhsbl.example.org. TXT
- urirhssub NAME_OF_RULE rhsbl_zone lookuptype subtest
- Specify a RHSBL-style domain lookup with a sub-test.
"NAME_OF_RULE" is the name of the rule
to be used, "rhsbl_zone" is the zone to
look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A).
"subtest" is a sub-test to
run against the returned data. The sub-test may be in one of the
following forms: m, n1-n2, or n/m, where n,n1,n2,m can be any of:
decimal digits, 0x followed by up to 8 hexadecimal digits, or an IPv4
address in quad-dot form. The 'A' records (IPv4 dotted address) as
returned by DNSBLs lookups are converted into a numerical form (r) and
checked against the specified sub-test as follows: for a range n1-n2 the
following must be true: (r >= n1 && r <= n2); for a n/m
form the following must be true: (r & m) == (n & m); for a
single value in quad-dot form the following must be true: r == n; for a
single decimal or hex form the following must be true:
((r & n) != 0) && ((r & 0xff000000) == 0x7f000000), i.e.
within 127.0.0.0/8
Some typical examples of a sub-test are: 127.0.1.2,
127.0.1.20-127.0.1.39, 127.2.3.0/255.255.255.0, 0.0.0.16/0.0.0.16,
0x10/0x10, 16, 0x10 .
Note that, as with
"urirhsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
Hostname to domain trimming is also done similarly.
Example:
urirhssub URIBL_RHSBL_4 rhsbl.example.org. A 127.0.0.4
urirhssub URIBL_RHSBL_8 rhsbl.example.org. A 8
- urinsrhsbl NAME_OF_RULE rhsbl_zone lookuptype
- Perform a RHSBL-style domain lookup against the contents of the NS records
for each URI. In other words, a URI using the domain
"foo.com" will cause an NS lookup to
take place; assuming that domain has an NS of
"ns0.bar.com", that will cause a lookup
of "bar.com.uriblzone.net". Note that
hostnames are stripped from both the domain used in the URI, and the
domain in the lookup.
"NAME_OF_RULE" is the name
of the rule to be used, "rhsbl_zone"
is the zone to look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A).
Note that, as with
"urirhsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
- urinsrhssub NAME_OF_RULE rhsbl_zone lookuptype subtest
- Specify a RHSBL-style domain-NS lookup, as above, with a sub-test.
"NAME_OF_RULE" is the name of the rule
to be used, "rhsbl_zone" is the zone to
look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A). "subtest" is
the sub-test to run against the returned data; see <urirhssub>.
Note that, as with
"urirhsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
- urifullnsrhsbl NAME_OF_RULE rhsbl_zone lookuptype
- Perform a RHSBL-style domain lookup against the contents of the NS records
for each URI. In other words, a URI using the domain
"foo.com" will cause an NS lookup to
take place; assuming that domain has an NS of
"ns0.bar.com", that will cause a lookup
of "ns0.bar.com.uriblzone.net".
"NAME_OF_RULE" is the name
of the rule to be used, "rhsbl_zone"
is the zone to look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A).
Note that, as with
"urirhsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
- urifullnsrhssub NAME_OF_RULE rhsbl_zone lookuptype subtest
- Specify a RHSBL-style domain-NS lookup, as above, with a sub-test.
"NAME_OF_RULE" is the name of the rule
to be used, "rhsbl_zone" is the zone to
look up domain names in, and
"lookuptype" is the type of lookup
(TXT or A). "subtest" is
the sub-test to run against the returned data; see <urirhssub>.
Note that, as with
"urirhsbl", you must also define a
body-eval rule calling
"check_uridnsbl()" to use this.
- tflags NAME_OF_RULE ips_only
- Only URIs containing IP addresses as the "host" component will
be matched against the named "urirhsbl"/"urirhssub"
rule.
- tflags NAME_OF_RULE domains_only
- Only URIs containing a non-IP-address "host" component will be
matched against the named "urirhsbl"/"urirhssub"
rule.
- tflags NAME_OF_RULE ns
- The 'ns' flag may be applied to rules corresponding to uridnsbl and
uridnssub directives. Host names from URLs will be mapped to their name
server IP addresses (a NS lookup followed by an A lookup), which in turn
will be sent to blocklists. This is a default when neither 'a' nor 'ns'
flags are specified.
- tflags NAME_OF_RULE a
- The 'a' flag may be applied to rules corresponding to uridnsbl and
uridnssub directives. Host names from URLs will be mapped to their IP
addresses, which will be sent to blocklists. When both 'ns' and 'a' flags
are specified, both queries will be performed.
- tflags NAME_OF_RULE notrim
- The full hostname component will be matched against the named
"urirhsbl"/"urirhssub" rule, instead of using the
trimmed domain. This works better, but the specific uribl must support
this method.
- uridnsbl_max_domains N (default: 20)
- The maximum number of domains to look up.
- parse_dkim_uris ( 0 / 1 )
- Include DKIM uris in lookups. This option is documented in
Mail::SpamAssassin::Conf.
The "uridnsbl_timeout" option has been
obsoleted by the "rbl_timeout" option. See
the "Mail::SpamAssassin::Conf" POD for
details on "rbl_timeout".
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