packlogic-generic(3) SiLK Tool Suite packlogic-generic(3)NAME
packlogic-generic.so - Packing logic for the generic site
SYNOPSIS
rwflowpack --packing-logic=packlogic-generic.so ...
DESCRIPTION
This manual page describes the packlogic-generic.so plug-in that
defines the packing logic that rwflowpack(8) may use to categorize flow
records. (This document uses the term plug-in, but the builder of SiLK
may choose to compile the packing logic into rwflowpack. See the SiLK
Installation Handbook for details.)
General Overview of rwflowpack
The primary job of rwflowpack is to categorize flow records into one or
more class and type pairs. The class and type pair (also called a
flowtype) are used by the analyst when selecting flow records from the
data store using rwfilter(1).
The settings that rwflowpack uses to categorize each flow record are
determined by two textual configuration files and a compiled plug-in
that is referred to as the packing logic.
The first of the configuration files is silk.conf(5) which specifies
the classes, types, and sensors that rwflowpack uses when writing files
and that rwfilter uses when selecting flow files.
The second configuration file is the sensor.conf(5) file. This file
contains multiple sensor blocks, where each block contains information
which the packing logic uses to categorize flow records collected by
the probes specified for that sensor.
The combination of a silk.conf file and a particular packing logic
plug-in define a site. By having the configuration and packing logic
outside of the core tools, users can more easily configure SiLK for
their particular installation and a single installation of SiLK can
support multiple sites.
This manual page describes the packing logic for the generic site. For
a description of the packing logic at another site, see that site's
manual page.
· packlogic-twoway(3)
Networks, Classes, and Types for the "generic" Site
The packlogic-generic.so plug-in uses three network names to describe
the logical address spaces that border the sensor:
internal
the space that is being monitored
external
the space outside the monitored network
null
the destination network for a flow that does not leave the router,
because either the flow was blocked by the router's access control
list or its destination was the router itself---e.g., a BGP message
The generic site assumes that all packets are either blocked by the
sensor (that is, their destination is the null network), or that the
packets cross the sensor so the source and destination networks always
differ.
The packing logic also assumes that the above networks completely
describe the space around the sensor. Since the null network is
strictly a destination network, any flow that does not originate from
the external network must originate from the internal network.
This allows the generic site to categorizes a flow record primarily by
comparing a flow record's source to the external network, and the
packing logic contains no comparisons to the internal network
The silk.conf file and packlogic-generic.so plug-in define a single
class, all.
The type assigned to a flow record within the all class is one of:
in, inweb
Records whose source is the external network and whose destination
is not the null network represent incoming traffic. The traffic is
split into multiple types, and these types allow the analysts to
query a subset of the flow records depending on their needs. Each
incoming flow record is split into the one of incoming types using
the following rules:
inweb
Contains traffic where the protocol is TCP \fIs0(6) and either
the source port or the destination port is one of 80, 443, or
8080
in Contains all other incoming traffic.
out, outweb
Records whose source is not the external network and whose
destination is not the null network represent outgoing traffic.
The traffic is split among the types using rules similar to those
for incoming traffic.
innull
Records whose source is the external network and whose destination
is the null network represent blocked incoming traffic.
outnull
Records whose source is not the external network and whose
destination is the null network represent blocked outgoing traffic.
Assigning a flow to source and destination networks
Since the generic site uses the external network to determine a flow
record's type, each sensor block in the sensor.conf(5) file must
specify a definition for the external network.
The sensor.conf file provides two ways to define a network: use the
NET-ipblocks statement to specify the NET network as a list of IP
address blocks, or use the NET-interfaces statement to specify the NET
network using a list of SNMP interfaces.
For the source network of a flow record to be considered external,
either the source IP (SiLK field "sIP") must appear in the list of
external-ipblocks or the incoming SNMP interface (SiLK field "in") must
appear in the list of external-interfaces. Note: If the probe block
that specifies where the flow was collected contains an interface-
values vlan statement, the SiLK "in" field contains the VLAN ID.
For the destination network of a flow record to be considered null,
either the destination IP ("dIP") must appear in the list of null-
ipblocks or the outgoing SNMP interface ("out") must appear in the list
of null-interfaces.
Consider the following two sensors:
sensor S2
ipfix-probes S2
external-ipblocks 172.16.0.0/16
internal-ipblocks 172.20.0.0/16
end sensor
sensor S3
ipfix-probes S3
external-interfaces 17,18,19
internal-interfaces 21,22,23
end sensor
A flow record collected at probe S2 whose "sIP" is 172.16.1.1 is
considered incoming, regardless of the destination IP.
A flow record collected at probe S3 whose "in" is 27 is considered
outgoing. (Since "in" does not match the external-interfaces, the
record is considered outgoing even though "in" does not match the
internal-interfaces either.)
There are two constructs in the sensor.conf file that help when
specifying these lists:
1. The NET-interfaces or NET-ipblocks statement in a sensor block may
use remainder to denote interfaces or IP blocks that do not appear
elsewhere in the block.
2. A group block can be used to give a name to a set of IP blocks or
SNMP interfaces which a sensor block can reference.
For details, see the sensor.conf(5) manual page.
Valid sensors
When using the packlogic-generic.so plug-in, the sensor blocks in the
sensor.conf file supports the following types of probes:
· ipfix
· netflow-v5
· netflow-v9
In addition, each sensor block must meet the following rules:
· Either external-interfaces or external-ipblocks must be specified.
And,
· A sensor cannot mix NET-ipblocks and NET-interfaces, with the
exception that null-interfaces are always allowed. And,
· Only one network on the sensor may use remainder. And,
· If a sensor contains only one NET-ipblocks statement, that
statement may not use remainder. (The NET-interfaces statement
does not have this restriction.)
Packing logic code
This section provides the logic used to assign the class and type at
the generic site.
A single sensor block will assign the flow record to a single class and
type, and processing of the flow for that sensor block stops as soon as
a type is assigned. When multiple sensor blocks reference the same
probe, the flow records collected by that probe are processed by each
of those sensor blocks.
A flow record is always assigned to the class all.
A textual description of the code used to assign the type is shown
here. As of SiLK 3.8.0, the type may be determined by the presence of
certain IPFIX or NetFlowV9 information elements.
· If "sIP" matches external-ipblocks or "in" matches external-
interfaces, then
· If "dIP" matches null-ipblocks or "out" matches null-
interfaces, pack as innull. Else,
· Pack as in or inweb.
· If "dIP" matches null-ipblocks or "out" matches null-interfaces,
pack as outnull. Else,
· Pack as out or outweb.
· Potentially modify the type: If the probe has a quirks setting that
includes "firewall-event" and if the incoming record contains the
"firewallEvent" or "NF_F_FW_EVENT" information element whose value
is 3 (flow denied), change the type where the flow is packed as
follows:
· If the flow was denied due to an ingress ACL
("NF_F_FW_EXT_EVENT" of 1001), pack as innull.
· If the flow was denied due to an egress ACL
("NF_F_FW_EXT_EVENT" of 1002), pack as outnull.
· If the flow's current type is innull, in, or inweb, pack as
innull.
· If the flow's current type is outnull, out, or outweb, pack as
outnull.
SEE ALSOrwfilter(1), rwflowpack(8), sensor.conf(5), silk.conf(5),
packlogic-twoway(3), silk(7), SiLK Installation Handbook
SiLK 3.11.0.1 2016-02-19 packlogic-generic(3)
