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# TCP Syslog Input Module

Module Name: imtcp

Author: Rainer Gerhards <rgerhards@adiscon.com>

Description:

Provides the ability to receive syslog messages via TCP. Encryption can be provided by using stunnel (an alternative is the use the imgssapi modul).

Multiple receivers may be configured by specifying $InputTCPServerRun multiple times. This is available since version 4.3.1, earlier versions do NOT support it.

Configuration Directives:

- $InputTCPServerAddtlFrameDelimiter <Delimiter>
  This directive permits to specify an additional frame delimiter for plain tcp syslog. The industry-standard specifies using the LF character as frame delimiter. Some vendors, notable Juniper in their NetScreen products, use an invalid frame delimiter, in Juniper's case the NUL character. This directive permits to specify the ASCII value of the delimiter in question. Please note that this does not guarantee that all wrong implementations can be cured with this directive. It is not even a sure fix with all versions of NetScreen, as I suggest the NUL character is the effect of a (common) coding error and thus will probably go away at some time in the future. But for the time being, the value 0 can probably be used to make rsyslog handle NetScreen's invalid syslog/tcp framing. For additional information, see this forum thread.
  If this doesn't work for you, please do not blame the rsyslog team. Instead file a bug report with Juniper!
  Note that a similar, but worse, issue exists with Cisco's IOS implementation. They do not use any framing at all. This is confirmed from Cisco's side, but there seems to be very limited interest in fixing this issue. This directive can not fix the Cisco bug. That would require much more code changes, which I was unable to do so far. Full details can be found at the Cisco tcp syslog anomaly page.
- $InputTCPServerRun <port>
  Starts a TCP server on selected port
- - $InputTCPMaxSessions <number>
  Sets the maximum number of sessions supported
- $InputTCPServerStreamDriverMode <number>
  Sets the driver mode for the currently selected network stream driver. <number> is driver specifc.
- $InputTCPServerInputName <name>
  Sets a name for the inputname property. If no name is set "imtcp" is used by default. Setting a name is not strictly necessary, but can be useful to apply filtering based on which input the message was received from.
- $InputTCPServerStreamDriverAuthMode <mode-string>
  Sets the authentication mode for the currently selected network stream driver. <mode-string> is driver specifc.
- $InputTCPServerStreamDriverPermittedPeer <id-string>
  Sets permitted peer IDs. Only these peers are able to connect to the listener. <id-string> semantics depend on the currently selected AuthMode and network stream driver. PermittedPeers may not be set in anonymous modes.

Caveats/Known Bugs:

- module always binds to all interfaces
- can not be loaded together with imgssapi (which includes the functionality of imtcp)

Sample:

This sets up a TCP server on port 514:

$ModLoad imtcp # needs to be done just once $InputTCPServerRun 514

[rsyslog.conf overview] [manual index] [rsyslog site]

This documentation is part of the rsyslog project.
Copyright © 2008 by Rainer Gerhards and Adiscon. Released under the GNU GPL version 3 or higher.