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|
**************************************
omudpspoof: UDP spoofing output module
**************************************
=========================== ===========================================================================
**Module Name:** **omudpspoof**
**Author:** David Lang <david@lang.hm> and `Rainer Gerhards <https://rainer.gerhards.net/>`_ <rgerhards@adiscon.com>
**Available Since:** 5.1.3
=========================== ===========================================================================
Purpose
=======
This module is similar to the regular UDP forwarder, but permits to
spoof the sender address. Also, it enables to circle through a number of
source ports.
**Important**: This module **requires root permissions**. This is a hard
requirement because raw socket access is necessary to fake UDP sender
addresses. As such, rsyslog cannot drop privileges if this module is
to be used. Ensure that you do **not** use `$PrivDropToUser` or
`$PrivDropToGroup`. Many distro default configurations (notably Ubuntu)
contain these statements. You need to remove or comment them out if you
want to use `omudpspoof`.
Configuration Parameters
========================
.. note::
Parameter names are case-insensitive.
Module Parameters
-----------------
Template
^^^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"word", "RSYSLOG_TraditionalForwardFormat", "no", "none"
This setting instructs omudpspoof to use a template different from
the default template for all of its actions that do not have a
template specified explicitly.
Action Parameters
-----------------
Target
^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"word", "none", "yes", "``$ActionOMUDPSpoofTargetHost``"
Host that the messages shall be sent to.
Port
^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"word", "514", "no", "``$ActionOMUDPSpoofTargetPort``"
Remote port that the messages shall be sent to. Default is 514.
SourceTemplate
^^^^^^^^^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"word", "RSYSLOG_omudpspoofDfltSourceTpl", "no", "``$ActionOMOMUDPSpoofSourceNameTemplate``"
This is the name of the template that contains a numerical IP
address that is to be used as the source system IP address. While it
may often be a constant value, it can be generated as usual via the
property replacer, as long as it is a valid IPv4 address. If not
specified, the build-in default template
RSYSLOG\_omudpspoofDfltSourceTpl is used. This template is defined as
follows:
$template RSYSLOG\_omudpspoofDfltSourceTpl,"%fromhost-ip%"
So in essence, the default template spoofs the address of the system
the message was received from. This is considered the most important
use case.
SourcePort.start
^^^^^^^^^^^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"integer", "32000", "no", "``$ActionOMUDPSpoofSourcePortStart``"
Specify the start value for circling the source ports. Start must be
less than or equal to sourcePort.End.
SourcePort.End
^^^^^^^^^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"integer", "42000", "no", "``$ActionOMUDPSpoofSourcePortEnd``"
Specify the end value for circling the source ports. End must be
equal to or more than sourcePort.Start.
MTU
^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"integer", "1500", "no", "none"
Maximum packet length to send.
Template
^^^^^^^^
.. csv-table::
:header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
:widths: auto
:class: parameter-table
"word", "RSYSLOG_TraditionalForwardFormat", "no", "``$ActionOMUDPSpoofDefaultTemplate``"
This setting instructs omudpspoof to use a template different from
the default template for all of its actions that do not have a
template specified explicitly.
Caveats/Known Bugs
==================
- **IPv6** is currently not supported. If you need this capability,
please let us know via the rsyslog mailing list.
- Throughput is MUCH smaller than when using omfwd module.
Examples
========
Forwarding message through multiple ports
-----------------------------------------
Forward the message to 192.168.1.1, using original source and port between 10000 and 19999.
.. code-block:: none
Action (
type="omudpspoof"
target="192.168.1.1"
sourceport.start="10000"
sourceport.end="19999"
)
Forwarding message using another source address
-----------------------------------------------
Forward the message to 192.168.1.1, using source address 192.168.111.111 and default ports.
.. code-block:: none
Module (
load="omudpspoof"
)
Template (
name="spoofaddr"
type="string"
string="192.168.111.111"
)
Action (
type="omudpspoof"
target="192.168.1.1"
sourcetemplate="spoofaddr"
)
|
