@PACKAGE@PackagesThe various source and binary packages are available at http://www.five-ten-sg.com/@PACKAGE@/packages/
The most recent documentation is available at http://www.five-ten-sg.com/@PACKAGE@/A Mercurial source
code repository for this project is available at http://hg.five-ten-sg.com/@PACKAGE@/.
2008-05-13@PACKAGE@1@PACKAGE@ @VERSION@@PACKAGE@detects suspicious routesSynopsis@PACKAGE@Description@PACKAGE@ is a daemon that monitors BGP
updates and SMTP connections to discover whether SMTP connections are
coming from ip addresses whose best route is suspicious. The @PACKAGE@.conf5 file specifies the syslog files
to be monitored, and the regular expressions (regex7) to be applied to new lines in those files. The discussion has focused on syslog files, but any ascii text
file can be used, so long as some other process appends lines to that
file, and those lines containing bgp updates can be matched
with some regular expression.Considering syslog files in particular, these are normally rotated
via logrotate. @PACKAGE@ properly detects and
handles this case by closing the old file, and reopening the newly
Load the configuration file, print a cannonical form
of the configuration on stdout, and exit.
Set the debug level to n.
Usage@PACKAGE@ -d 2Configuration
The configuration file is documented in @PACKAGE@.conf5. Any change to the config file will cause it to be
reloaded within three minutes.
Consider the hypothetical case of a spammer who is connected via a
provider that does not filter BGP routing announcements. The spammer
then has some options to announce ip address space to be used for
sending spam. Note that we only consider cases where the spammer
simply wants to anonymously use some ip address space. This is very
different from the case where the attacker wants to use some specific
address space belonging to another organization in order to impersonate
some service provided by that other organization.
They can announce a more specific route, for example a /24, inside a
larger block. For example, consider 18.104.22.168/16. If the spammer
pokes around, they can probably find an unused /24 in there. So they
announce 22.214.171.124/24 and then send spam from that block. There
are two problems with this scheme. First, the announcement of such a
smaller block may be filtered out by many BGP routers, reducing their
reachability to their spam targets. Second, they may have made a
mistake, and that /24 is actually in use by some UCLA service that
will notice their hijack.
They can announce a less specific route, for example a /16, covering
some individual smaller blocks. For example, they could announce
126.96.36.199/16. The spammer could then avoid the four existing
announcements inside that block, and instead spam from
188.8.131.52/17. That gives them 32K ip addresses to work with. The
advantage here is that their announcement of a large block won't be
filtered out by as many (if any) BGP routers, giving them better reachability
to their spam targets. And they know they won't interfere with any
existing use of that address space, since there was no previous BGP
announcement of that /17 or any subset of it.
Or they can simply announce a prefix that is not assigned to anyone.
For example, they could simply start announcing 184.108.40.206/16. This
has many of the same advantages as the previous scheme, but some BGP
routers may be configured to drop such bogon announcements, again
potentially reducing their reachability to their spam targets.
In each of these cases, the spammer can use BGP to announce some
address space, then send spam from those addresses, and then withdraw
the route annoucement. This would make it difficult for the recipient of
such spam to determine who actually sent it.
In a paper from 2006 published at
, Ramachandran and Feamster claim evidence for the statement
that spammers are using such short-lived bogus BGP route announcements
to send spam from hijacked parts of the IPv4 address space.
The question is, are spammers actually doing this today, or is this
just a hypothetical spam tactic that they could use in the future? To
help answer that question, this package monitors BGP annoucements,
classifies some of them as suspicious, and logs instances of SMTP
connections from suspicious prefixes.
We track the history of the AS adjacency graph, by computing the union
of all AS adjacent pairs over all the announced prefixes. For example,
220.127.116.11/16 is currently announced here with an AS path of '22298
19080 3549 6517 14981', so we add (22298,19080) (19080,3549)
(3549,6517) and (6517,14981) as valid adjacent AS pairs.
We also track the history of the origin AS for each announced prefix. Both
the origin AS and the AS adjacency pairs are tracked via the following
algorithm that runs every hour.
For each prefix, (prefix[*] *= 0.99) to exponentially decay the current
prefix origin counts. Then, for each prefix, if the prefix is announced,
(prefix[current.origin]++) increments the hourly count for the current origin.
The decay factor of 0.99 gives the counts a half life of about 69 hours.
The same is done with the hourly counts for each observed AS adjacent pair.
A prefix announcement is suspicious if the prefix[origin] count is less
than 3.0, or if the AS path contains any adjacent AS pair with a count
less than 3.0.
PHAS is another
system that attempts to detect address space hijacking, but it is not
correlated with SMTP connections or spam attempts.
another system that attempts to detect address space hijacking, but it
is not correlated with SMTP connections or spam attempts. IAR uses
methods detailed in PGBGP
to detect suspicious routes. One problem with PGBGP as applied to our
hypothetical spammer problem, is that PGBGP is primarily looking for
hijacks where the attacker actually wants some specific ip address
space, either for a denial of service, or to impersonate the actual
owner. Our hypothetical spammer does not care about that - they only
care about sending spam anonymously. In particular, PGBGP ignores
super-prefix hijacks, but it seems likely that that is the preferred
method for our hypothetical spammer. However, the PGBGP paper does provide
useful data on the required timescale to avoid most of the normal AS
Copyright (C) 2008 by 510 Software Group <email@example.com>
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
You should have received a copy of the GNU General Public License along
with this program; see the file COPYING. If not, please write to the
Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
2008-05-13@PACKAGE@.conf5@PACKAGE@ @VERSION@@PACKAGE@.confconfiguration file for @PACKAGE@Synopsis@PACKAGE@.confDescriptionThe @PACKAGE@.conf configuration file is
specified by this partial bnf description. The entire config file
is case sensitive. All the keywords are lower case.