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| author | Rainer Gerhards <rgerhards@adiscon.com> | 2007-07-04 07:58:06 +0000 |
|---|---|---|
| committer | Rainer Gerhards <rgerhards@adiscon.com> | 2007-07-04 07:58:06 +0000 |
| commit | f7ab1e5daf99ad76f1a40cfc539a29eb676b46cc (patch) | |
| tree | fa24f9c32b4ddac228b64a8aa8f082a3458013a5 /doc/rsyslog_conf.html | |
| parent | 489a51be2336584d3f90abbb4aa560197177c925 (diff) | |
| download | rsyslog-f7ab1e5daf99ad76f1a40cfc539a29eb676b46cc.tar.gz rsyslog-f7ab1e5daf99ad76f1a40cfc539a29eb676b46cc.tar.xz rsyslog-f7ab1e5daf99ad76f1a40cfc539a29eb676b46cc.zip | |
documented new dynamic file naming feature
Diffstat (limited to 'doc/rsyslog_conf.html')
| -rw-r--r-- | doc/rsyslog_conf.html | 1547 |
1 files changed, 788 insertions, 759 deletions
diff --git a/doc/rsyslog_conf.html b/doc/rsyslog_conf.html index fb025b84..977301e4 100644 --- a/doc/rsyslog_conf.html +++ b/doc/rsyslog_conf.html @@ -1,760 +1,789 @@ -<html>
-<head>
-<title>rsyslog.conf file</title>
-</head>
-<body>
-<h1>rsyslog.conf configuration file</h1>
-<p><b>This document is currently being enhanced. Please pardon its current
-appearance.</b></p>
-<p><b>Rsyslogd is configured via the rsyslog.conf file</b>, typically found in
-/etc. By default, rsyslogd reads the file /etc/rsyslog.conf.</p>
-<p>While rsyslogd contains enhancements over standard syslogd, efforts have been
-made to keep the configuration file as compatible as possible. While, for
-obvious reasons, <a href="features.html">enhanced features</a> require a
-different config file syntax, rsyslogd should be able to work with a standard
-syslog.conf file. This is especially useful while you are migrating from syslogd
-to rsyslogd.</p>
-<h2>Basic Structure</h2>
-<p>Rsyslog supports standard sysklogd's configuration file format and extends
-it. So in general, you can take a "normal" syslog.conf and use it together with
-rsyslogd. It will understand everything. However, to use most of rsyslogd's
-unique features, you need to add extended configuration directives.<p>Rsyslogd
-supports the classical, selector-based rule lines. They are still at the heart
-of it and all actions are initiated via rule lines. A rule lines is any line not
-starting with a $ or the comment sign (#). Lines starting with $ carry
-rsyslog-specific directives.<p>Every rule line consists of two fields, a selector field and an action field.
-These two fields are separated by one or more spaces or tabs. The selector field
-specifies a pattern of facilities and priorities belonging to the specified
-action.<br>
-<br>
-Lines starting with a hash mark ("#'') and empty lines are ignored.
-<h2>Allowed Sender Lists</h2>
-<p>Allowed sender lists can be used to specify which remote systems are allowed
-to send syslog messages to rsyslogd. With them, further hurdles can be placed
-between an attacker and rsyslogd. If a message from a system not in the allowed
-sender list is received, that message is discarded. A diagnostic message is
-logged, so that the fact is recorded (this message can be turned off with the
-"-w" rsyslogd command line option).</p>
-<p>Allowed sender lists can be defined for UDP and TCP senders seperately. There
-can be as many allowed senders as needed. The syntax to specify them is:</p>
-<p><code><b>$AllowedSender <protocol>, ip[/bits], ip[/bits]</b></code></p>
-<p>"$AllowedSender" is the directive - it must be written exactly as shown and
-the $ must start at the first column of the line. "<protocol>" is either "UDP"
-or "TCP". It must immediately be followed by the comma, else you will receive an
-error message. "ip[/bits]" is a machine or network ip address as in
-"192.0.2.0/24" or "127.0.0.1". If the "/bits" part is omitted, a single host is
-assumed (32 bits or mask 255.255.255.255). "/0" is not allowed, because that
-would match any sending system. If you intend to do that, just remove all $AllowedSender
-directives. If more than 32 bits are requested, they are adjusted to 32.
-Multiple allowed senders can be specified in a comma-delimited list. Also,
-multiple $AllowedSender lines can be given. They are all combined into one UDP
-and one TCP list. Performance-wise, it is good to specify those allowed senders
-with high traffic volume before those with lower volume. As soon as a match is
-found, no further evaluation is necessary and so you can save CPU cycles.</p>
-<p>Rsyslogd handles allowed sender detection very early in the code, nearly as
-the first action after receiving a message. This keeps the access to potential
-vulnerable code in rsyslog at a minimum. However, it is still a good idea to
-impose allowed sender limitations via firewalling.</p>
-<p><b>WARNING:</b> by UDP design, rsyslogd can not identify a spoofed sender
-address in UDP syslog packets. As such, a malicous person could spoof the adress
-of an allowed sender, send such packets to rsyslogd and rsyslogd would accept
-them as being from the faked sender. To prevent this, use syslog via TCP
-exclusively. If you need to use UDP-based syslog, make sure that you do proper
-egress and ingress filtering at the firewall and router level.</p>
-<p>An example for an allowed sender list is as follows:</p>
-<p><code><b>$AllowedSender UDP, 127.0.0.1, 192.0.2.0/24</b></code></p>
-<h2>Templates</h2>
-<p>Templates are a key feature of rsyslog. They allow to specify any format a user
-might want. Every output in rsyslog uses templates - this holds true for files,
-user messages and so on. The database writer expects its template to be a proper
-SQL statement - so this is highly customizable too. You might ask how does all
-of this work when no templates at all are specified. Good question ;) The answer
-is simple, though. Templates compatible with the stock syslogd formats are
-hardcoded into rsyslogd. So if no template is specified, we use one of these
-hardcoded templates. Search for "template_" in syslogd.c and you will find the
-hardcoded ones.</p>
-<p>A template consists of a template directive, a name, the actual template text
-and optional options. A sample is:</p>
-<blockquote><code>$template MyTemplateName,"\7Text %property% some more text\n",<options></code></blockquote>
-<p>The "$template" is the template directive. It tells rsyslog that this line
-contains a template. "MyTemplateName" is the template name. All
-other config lines refer to this name. The text within quotes is the actual
-template text. The backslash is an escape character, much as it is in C. It does
-all these "cool" things. For example, \7 rings the bell (this is an ASCII
-value), \n is a new line. C programmers and perl coders have the advantage of
-knowing this, but the set in rsyslog is a bit restricted currently.
-<p>
-All text in the template is used literally, except for things within percent
-signs. These are properties and allow you access to the contents of the syslog
-message. Properties are accessed via the property replacer (nice name, huh) and
-it can do cool things, too. For example, it can pick a substring or do
-date-specific formatting. More on this is below, on some lines of the property
-replacer.<br>
-<br>
-The <options> part is optional. It carries options influencing the template as
-whole. See details below. Be sure NOT to mistake template options with property
-options - the later ones are processed by the property replacer and apply to a
-SINGLE property, only (and not the whole template).<br>
-<br>
-Template options are case-insensitive. Currently defined are: </p>
-<p><b>sql</b> - format the string suitable for a SQL statement in MySQL format. This will
-replace single quotes ("'") and the backslash character by their
-backslash-escaped counterpart ("\'" and "\\") inside each field. Please note
-that in MySQL configuration, the <code class="literal">NO_BACKSLASH_ESCAPES</code>
-mode must be turned off for this format to work (this is the default).</p>
-<p><b>stdsql</b> - format the string suitable for a SQL statement that is to be
-sent to a standards-compliant sql server. This will
-replace single quotes ("'") by two single quotes ("''") inside each field.
-You must use stdsql together with MySQL if in MySQL configuration the
-<code class="literal">NO_BACKSLASH_ESCAPES</code> is turned on.</p>
-<p>Either the <b>sql</b> or <b>stdsql</b>
-option <b>must</b> be specified when a template is used for writing to a database,
-otherwise injection might occur. Please note that due to the unfortunate fact
-that several vendors have violated the sql standard and introduced their own
-escape methods, it is impossible to have a single option doing all the work.
-So you yourself must make sure you are using the right format. <b>If you choose
-the wrong one, you are still vulnerable to sql injection.</b><br>
-<br>
-Please note that the database writer *checks* that the sql option is present in
-the template. If it is not present, the write database action is disabled. This
-is to guard you against accidential forgetting it and then becoming vulnerable
-to SQL injection. The sql option can also be useful with files - especially if
-you want to import them into a database on another machine for performance
-reasons. However, do NOT use it if you do not have a real need for it - among
-others, it takes some toll on the processing time. Not much, but on a really
-busy system you might notice it ;)</p>
-<p>The default template for the write to database action has the sql option set.
-As we currently support only MySQL and the sql option matches the default MySQL
-configuration, this is a good choice. However, if you have turned on
-<code class="literal">NO_BACKSLASH_ESCAPES</code> in your MySQL config, you need
-to supply a template with the stdsql option. Otherwise you will become
-vulnerable to SQL injection. <br>
-<br>
-To escape:<br>
-% = \%<br>
-\ = \\ --> '\' is used to escape (as in C)<br>
-$template TraditionalFormat,%timegenerated% %HOSTNAME% %syslogtag%%msg%\n"<br>
-<br>
-Properties can be accessed by the <a href="property_replacer.html">property replacer</a>
-(see there for details).</p>
-<h2>Output Channels</h2>
-<p>Output Channels are a new concept first introduced in rsyslog 0.9.0. As of this
-writing, it is still unclear if they will stay in rsyslog or go away. So if you
-use them, be prepared to change you configuration file syntax when you upgrade
-to a later release.<br>
-<br>
-The idea behind output channel definitions is that it shall provide an umbrella
-for any type of output that the user might want. In essence,<br>
-this is the "file" part of selector lines (and this is why we are not sure
-output channel syntax will stay after the next review). There is a<br>
-difference, though: selector channels both have filter conditions (currently
-facility and severity) as well as the output destination. Output channels define
-the output defintion, only. As of this build, they can only be used to write to
-files - not pipes, ttys or whatever else. If we stick with output channels, this
-will change over time.</p>
-<p>In concept, an output channel includes everything needed to know about an
-output actions. In practice, the current implementation only carries<br>
-a filename, a maximum file size and a command to be issued when this file size
-is reached. More things might be present in future version, which might also
-change the syntax of the directive.</p>
-<p>Output channels are defined via an $outchannel directive. It's syntax is as
-follows:<br>
-<br>
-$outchannel name,file-name,max-size,action-on-max-size<br>
-<br>
-name is the name of the output channel (not the file), file-name is the file
-name to be written to, max-size the maximum allowed size and action-on-max-size
-a command to be issued when the max size is reached.<br>
-<br>
-Please note that max-size is queried BEFORE writing the log message to the file.
-So be sure to set this limit reasonably low so that any message might fit. For
-the current release, setting it 1k lower than you expected is helpful. The
-max-size must always be specified in bytes - there are no special symbols (like
-1k, 1m,...) at this point of development.<br>
-<br>
-Keep in mind that $outchannel just defines a channel with "name". It does not
-activate it. To do so, you must use a selector line (see below). That selector
-line includes the channel name plus an $ sign in front of it. A sample might be:<br>
-<br>
-*.* $mychannel<br>
-<br>
-In its current form, output channels primarily provide the ability to size-limit
-an output file. To do so, specify a maximum size. When this size is reachead,
-rsyslogd will execute the action-on-max-size command and then reopen the file
-and retry. The command should be something like a log rotation script or a
-similar thing.</p>
-<blockquote>
- <p><b>WARNING</b>
- <p>The current command logic is a quick hack. It simply issues the command via a
-system() call, which is very dirty. Don't make rsyslogd a suid
-binary and use action-on-max-size commands - this will mess up things. Fixing
-this is on top of the todo list and the fix will hopefully
-appear soon.</p>
-</blockquote>
-<p>If there is no action-on-max-size command or the command did not resolve the
-situation, the file is closed and never reopened by rsyslogd (except, of course,
-by huping it). This logic was integrated when we first experienced severe issues
-with files larger 2gb, which could lead to rsyslogd dumping core. In such cases,
-it is more appropriate to stop writing to a single file. Meanwhile, rsyslogd has
-been fixed to support files larger 2gb, but obviously only on file systems and
-operating system versions that do so. So it can still make sense to enforce a
-2gb file size limit.</p>
-<h2>Filter Conditions</h2>
-<p>Rsyslog offers two different types "filter conditions":</p>
-<ul>
- <li>"traditional" severity and facility based selectors</li>
- <li>property-based filters</li>
-</ul>
-<h3>Blocks</h3>
-<p>Rsyslogd supports BSD-style blocks inside rsyslog.conf. Each block of lines
-is separated from the previous block by a program or hostname specification. A
-block will only log messages corresponding to the most recent program and
-hostname specifications given. Thus, a block which selects ‘ppp’ as the program,
-directly followed by a block that selects messages from the hostname ‘dialhost’,
-then the second block will only log messages from the ppp program on dialhost.
-</p>
-<p>A program specification is a line beginning with ‘!prog’ and the following
-blocks will be associated with calls to syslog from that specific program. A
-program specification for ‘foo’ will also match any message logged by the kernel
-with the prefix ‘foo: ’. A hostname specification of the form ‘+hostname’ and
-the following blocks will be applied to messages received from the specified
-hostname. Alternatively, a hostname specification ‘-hostname’ causes the
-following blocks to be applied to messages from any host but the one specified.
-If the hostname is given as ‘@’, the local hostname will be used. (NOT YET
-IMPLEMENTED) A program or hostname specification may be reset by giving the
-program or hostname as ‘*’.</p>
-<p>Please note that the "#!prog", "#+hostname" and "#-hostname" syntax available
-in BSD syslogd is not supported by rsyslogd. By default, no hostname or program
-is set.</p>
-<h3>Selectors</h3>
-<p><b>Selectors are the traditional way of filtering syslog messages.</b> They
-have been kept in rsyslog with their orginal syntax, because it is well-known,
-highly effective and also needed for compatibility with stock syslogd
-configuration files. If you just need to filter based on priority and facility,
-you should do this with selector lines. They are <b>not</b> second-class
-citicens in rsyslog and offer the best performance for this job.</p>
-<p>The selector field itself again consists of two parts, a facility and a
-priority, separated by a period (``.''). Both parts are case insenstive and can
-also be specified as decimal numbers, but don't do that, you have been warned.
-Both facilities and priorities are described in rsyslog(3). The names mentioned
-below correspond to the similar LOG_-values in /usr/include/rsyslog.h.<br><br>The facility is one of the following keywords: auth, authpriv, cron, daemon,
-kern, lpr, mail, mark, news, security (same as auth), syslog, user, uucp and
-local0 through local7. The keyword security should not be used anymore and mark
-is only for internal use and therefore should not be used in applications.
-Anyway, you may want to specify and redirect these messages here. The facility
-specifies the subsystem that produced the message, i.e. all mail programs log
-with the mail facility (LOG_MAIL) if they log using syslog.<br><br>Please note that the upcoming next syslog-RFC specifies many more facilities.
-Support for them will be added in a future version of rsyslog, which might
-require changes to existing configuration files.<br><br>The priority is one of the following keywords, in ascending order: debug, info,
-notice, warning, warn (same as warning), err, error (same as err), crit, alert,
-emerg, panic (same as emerg). The keywords error, warn and panic are deprecated
-and should not be used anymore. The priority defines the severity of the message<br>
-<br>The behavior of the original BSD syslogd is that all messages of the specified
-priority and higher are logged according to the given action. Rsyslogd behaves the same, but has some extensions.<br><br>In addition to the above mentioned names the rsyslogd(8) understands the
-following extensions: An asterisk (``*'') stands for all facilities or all
-priorities, depending on where it is used (before or after the period). The
-keyword none stands for no priority of the given facility.<br><br>You can specify multiple facilities with the same priority pattern in one
-statement using the comma (``,'') operator. You may specify as much facilities
-as you want. Remember that only the facility part from such a statement is
-taken, a priority part would be skipped.</p>
-<p>Multiple selectors may be specified for a single action using the semicolon
-(``;'') separator. Remember that each selector in the selector field is capable
-to overwrite the preceding ones. Using this behavior you can exclude some
-priorities from the pattern.</p>
-<p>Rsyslogd has a syntax extension to the original BSD source, that makes its
-use more intuitively. You may precede every priority with an equation sign
-(``='') to specify only this single priority and not any of the above. You may
-also (both is valid, too) precede the priority with an exclamation mark (``!'')
-to ignore all that priorities, either exact this one or this and any higher
-priority. If you use both extensions than the exclamation mark must occur before
-the equation sign, just use it intuitively.</p>
-<h3>Property-Based Filters</h3>
-<p>Property-based filters are unique to rsyslogd. They allow to filter on any
-property, like HOSTNAME, syslogtag and msg. A list of all currently-supported
-properties can be found in the <a href="property_replacer.html">property
-replacer documentation</a> (but keep in mind that only the properties, not the
-replacer is supported). With this filter, each properties can be checked against
-a specified value, using a specified compare operation. Currently, there is only
-a single compare operation (contains) available, but additional operations will be added in the
-future.</p>
-<p>A property-based filter must start with a colon in column 0. This tells
-rsyslogd that it is the new filter type. The colon must be followed by the
-property name, a comma, the name of the compare operation to carry out, another
-comma and then the value to compare against. This value must be quoted. There
-can be spaces and tabs between the commas. Property names and compare operations
-are case-sensitive, so "msg" works, while "MSG" is an invalid property name. In
-brief, the syntax is as follows:</p>
-<p><code><b>:property, [!]compare-operation, "value"</b></code></p>
-<p>The following <b>compare-operations</b> are currently supported:</p>
-<table border="1" width="100%" id="table1">
- <tr>
- <td>contains</td>
- <td>Checks if the string provided in value is contained in the property.
- There must be an exact match, wildcards are not supported.</td>
- </tr>
- <tr>
- <td>isequal</td>
- <td>Compares the "value" string provided and the property contents.
- These two values must be exactly equal to match. The difference to
- contains is that contains searchs for the value anywhere inside the
- property value, whereas all characters must be identical for isequal. As
- such, isequal is most useful for fields like syslogtag or FROMHOST,
- where you probably know the exact contents.</td>
- </tr>
- <tr>
- <td>startswith</td>
- <td>Checks if the value is found exactly at the beginning of the
- property value. For example, if you search for "val" with<p><code><b>:msg,
- startswith, "val"</b></code></p>
- <p>it will be a match if msg contains "values are in this message" but
- it won't match if the msg contains "There are values in this message"
- (in the later case, contains would match). Please note that "startswith"
- is by far faster than regular expressions. So even once they are
- implemented, it can make very much sense (performance-wise) to use "startswith".</td>
- </tr>
- <tr>
- <td>regex</td>
- <td><b>NOT YET IMPLEMENTED</b> - value holds an regular expression</td>
- </tr>
-</table>
-<p>You can use the bang-character (!) immediately in front of a
-compare-operation, the outcome of this operation is negated. For example, if msg
-contains "This is an informative message", the following sample would not match:</p>
-<p><code><b>:msg, contains, "error"</b></code></p>
-<p>but this one matches:</p>
-<p><code><b>:msg, !contains, "error"</b></code></p>
-<p>Using negation can be useful if you would like to do some generic processing
-but exclude some specific events. You can use the discard action in conjunction
-with that. A sample would be:</p>
-<p><code><b>*.* /var/log/allmsgs-including-informational.log<br>
-:msg, contains, "informational" <font color="#FF0000" size="4">~</font>
-<br>*.* /var/log/allmsgs-but-informational.log</b></code></p>
-<p>Do not overlook the red tilde in line 2! In this sample, all messages are
-written to the file allmsgs-including-informational.log. Then, all messages
-containing the string "informational" are discarded. That means the config file
-lines below the "discard line" (number 2 in our sample) will not be applied to
-this message. Then, all remaining lines will also be written to the file
-allmsgs-but-informational.log.</p>
-<p><b>Value</b> is a quoted string. It supports some escape sequences:</p>
-<p>\" - the quote character (e.g. "String with \"Quotes\"")<br>
-\\ - the backslash character (e.g. "C:\\tmp")</p>
-<p>Escape sequences always start with a backslash. Additional escape sequences
-might be added in the future. Backslash characters <b>must</b> be escaped. Any
-other sequence then those outlined above is invalid and may lead to
-unpredictable results.</p>
-<p>Probably, "msg" is the most prominent use case of property based filters. It
-is the actual message text. If you would like to filter based on some message
-content (e.g. the presence of a specific code), this can be done easily by:</p>
-<p><code><b>:msg, contains, "ID-4711"</b></code></p>
-<p>This filter will match when the message contains the string "ID-4711". Please
-note that the comparison is case-sensitive, so it would not match if "id-4711"
-would be contained in the message.</p>
-<p>Getting property-based filters right can sometimes be challenging. In order
-to help you do it with as minimal effort as possible, rsyslogd spits out debug
-information for all property-based filters during their evaluation. To enable
-this, run rsyslogd in foreground and specify the "-d" option.</p>
-<p>Boolean operations inside property based filters (like 'message contains
-"ID17" or message contains "ID18"') are currently not supported
-(except for "not" as outlined above). Please note
-that while it is possible to query facility and severity via property-based filters,
-it is far more advisable to use classic selectors (see above) for those
-cases.</p>
-<h2>ACTIONS</h2>
-<p>The action field of a rule describes what to do with the message. In general,
-message content is written to a kind of "logfile". But also other actions might
-be done, like writing to a database table or forwarding to another host.<br>
-<br>
-Templates can be used with all actions. If used, the specified template is used
-to generate the message content (instead of the default template). To specify a
-template, write a semicolon after the action value immediately followed by the
-template name.<br>
-<br>
-Beware: templates MUST be defined BEFORE they are used. It is OK to define some
-templates, then use them in selector lines, define more templates and use use
-them in the following selector lines. But it is NOT permitted to use a template
-in a selectore line that is above its definition. If you do this, the selector
-line will be ignored.</p>
-<h3>Regular File</h3>
-<p>Typically messages are logged to real files. The file has to be specified with
-full pathname, beginning with a slash "/''.<br>
-<br>
-You may prefix each entry with the minus ``-'' sign to omit syncing the file
-after every logging. Note that you might lose information if the system crashes
-right behind a write attempt. Nevertheless this might give you back some
-performance, especially if you run programs that use<br>
-logging in a very verbose manner.</p>
-<p>If your system is connected to a reliable UPS and you receive lots of log
-data (e.g. firewall logs), it might be a very good idea to turn of
-syncing by specifying the "-" in front of the file name. </p>
-<h3>Named Pipes</h3>
-<p>This version of rsyslogd(8) has support for logging output to named pipes (fifos).
-A fifo or named pipe can be used as a destination for log messages by prepending
-a pipe symbol (``|'') to the name of the file. This is handy for debugging. Note
-that the fifo must be created with the mkfifo(1) command before rsyslogd(8) is
-started.</p>
-<h3>Terminal and Console</h3>
-<p>If the file you specified is a tty, special tty-handling is done, same with
-/dev/console.</p>
-<h3>Remote Machine</h3>
-<p>Rsyslogd provides full remote logging, i.e. is able to send messages to a
-remote host running rsyslogd(8) and to receive messages from remote hosts.
-Using this feature you're able to control all syslog messages on one host, if
-all other machines will log remotely to that. This tears down<br>
-administration needs.<br>
-<br>
-<b>Please note that this version of rsyslogd by default does NOT forward messages
-it has received from the network to another host. Specify the "-h" option to enable this.</b></p>
-<p>To forward messages to another host, prepend the hostname with the at sign ("@").
-A single at sign means that messages will be forwarded via UDP protocol (the
-standard for syslog). If you prepend two at signs ("@@"), the messages will be
-transmitted via TCP. Please note that plain TCP based syslog is not officially
-standardized, but most major syslogds support it (e.g. syslog-ng or WinSyslog).
-The forwarding action indicator (at-sign) can be followed by one or more options.
-If they are given, they must be immediately (without a space) following the
-final at sign and be enclosed in parenthesis. The individual options must be
-separated by commas. The following options are right now defined:</p>
-<table border="1" width="100%" id="table2">
- <tr>
- <td>
- <p align="center"><b>z<number></b></td>
- <td>Enable zlib-compression for the message. The <number> is the
- compression level. It can be 1 (lowest gain, lowest CPU overhead) to 9 (maximum
- compression, highest CPU overhead). The level can also be 0, which means
- "no compression". If given, the "z" option is ignored. So this does not
- make an awful lot of sense. There is hardly a difference between level 1
- and 9 for typical syslog messages. You can expect a compression gain
- between 0% and 30% for typical messages. Very chatty messages may
- compress up to 50%, but this is seldomly seen with typicaly traffic.
- Please note that rsyslogd checks the compression gain. Messages with 60
- bytes or less will never be compressed. This is because compression gain
- is pretty unlikely and we prefer to save CPU cycles. Messags over that
- size are always compressed. However, it is checked if there is a gain in
- compression and only if there is, the compressed message is transmitted.
- Otherwise, the uncompressed messages is transmitted. This saves the
- receiver CPU cycles for decompression. It also prevents small message to
- actually become larger in compressed form.<p><b>Please note that when a
- TCP transport is used, compression will also turn on
- syslog-transport-tls framing. See the "o" option for important
- information on the implications.</b></p>
- <p>Compressed messages are automatically detected and decompressed by
- the receiver. There is nothing that needs to be configured on the
- receiver side.</td>
- </tr>
- <tr>
- <td>
- <p align="center"><b>o</b></td>
- <td><b>This option is experimental. Use at your own risk and only if you
- know why you need it! If in doubt, do NOT turn it on.</b><p>This option
- is only valid for plain TCP based transports. It selects a different
- framing based on IETF internet draft syslog-transport-tls-06. This
- framing offers some benefits over traditional LF-based framing. However,
- the standardization effort is not yet complete. There may be changes in
- upcoming versions of this standard. Rsyslog will be kept in line with
- the standard. There is some chance that upcoming changes will be
- incompatible to the current specification. In this case, all systems
- using -transport-tls framing must be upgraded. There will be no effort
- made to retain compatibility between different versions of rsyslog. The
- primary reason for that is that it seems technically impossible to
- provide compatibility between some of those changes. So you should take
- this note very serious. It is not something we do not *like* to do (and
- may change our mind if enough pepole beg...), it is something we most
- probably *can not* do for technical reasons (aka: you can beg as much as
- you like, it won't change anything...).</p>
- <p>The most important implication is that compressed syslog messages via
- TCP must be considered with care. Unfortunately, it is technically
- impossible to transfer compressed records over traditional syslog plain
- tcp transports, so you are left with two evil choices...</td>
- </tr>
-</table>
-<p><br>
-The hostname may be followed by a colon and the destination port.</p>
-<p>The following is an example selector line with forwarding:</p>
-<p>*.* @@(o,z9)192.168.0.1:1470</p>
-<p>In this example, messages are forwarded via plain TCP with experimental
-framing and maximum compression to the host 192.168.0.1 at port 1470.</p>
-<p>*.* @192.168.0.1</p>
-<p>In the example above, messages are forwarded via UDP to the machine
-192.168.0.1, the destination port defaults to 514. Messages will not be
-compressed.</p>
-<h3>List of Users</h3>
-<p>Usually critical messages are also directed to ``root'' on that machine. You can
-specify a list of users that shall get the message by simply writing the login.
-You may specify more than one user by separating them with commas (",''). If
-they're logged in they get the message. Don't think a mail would be sent, that
-might be too late.</p>
-<h3>Everyone logged on</h3>
-<p>Emergency messages often go to all users currently online to notify them that
-something strange is happening with the system. To specify this wall(1)-feature
-use an asterisk ("*'').</p>
-<h3>Database Table</h3>
-<p>This allows logging of the message to a database table. Currently, only MySQL
-databases are supported. By default, a MonitorWare-compatible schema is required
-for this to work. You can create that schema with the createDB.SQL file that
-came with the rsyslog package. You can also<br>
-use any other schema of your liking - you just need to define a proper template
-and assign this template to the action.<br>
-<br>
-The database writer is called by specifying a greater-then sign (">") in front
-of the database connect information. Immediately after that<br>
-sign the database host name must be given, a comma, the database name, another
-comma, the database user, a comma and then the user's password. If a specific
-template is to be used, a semicolong followed by the template name can follow
-the connect information. This is as follows:<br>
-<br>
->dbhost,dbname,dbuser,dbpassword;dbtemplate</p>
-<h3>Discard</h3>
-<p>If the discard action is carried out, the received message is immediately
-discarded. No further processing of it occurs. Discard has primarily been added
-to filter out messages before carrying on any further processing. For obvious
-reasons, the results of "discard" are depending on where in the configuration
-file it is being used. Please note that once a message has been discarded there
-is no way to retrive it in later configuration file lines.</p>
-<p>Discard can be highly effective if you want to filter out some annoying
-messages that otherwise would fill your log files. To do that, place the discard
-actions early in your log files. This often plays well with property-based
-filters, giving you great freedom in specifying what you do not want.</p>
-<p>Discard is just the single tilde character with no further parameters:</p>
-<p>~</p>
-<p>For example,</p>
-<p>*.* ~</p>
-<p>discards everything (ok, you can achive the same by not running rsyslogd at
-all...).</p>
-<h3>Output Channel</h3>
-<p>Binds an output channel definition (see there for details) to this action.
-Output channel actions must start with a $-sign, e.g. if you would like to bind
-your output channel definition "mychannel" to the action, use "$mychannel".
-Output channels support template definitions like all all other actions.</p>
-<h3>Shell Execute</h3>
-<p>This executes a program in a subshell. The programm is passed the
-template-generated message as the only command line parameter. Rsyslog waits
-until the program terminates and only then continues to run.</p>
-<p>^programm-to-execute;template</p>
-<p>The program-to-execute can be any valid executable.</p>
-<p><b>WARNING:</b> The Shell Execute action was added to serve an urgent need.
-While it is considered reasonable save when used with some thinking, its
-implications must be considered. The current implementation uses a system() call
-to execute the command. This is not the best way to do it (and will hopefully
-changed in further releases). Also, proper escaping of special characters is
-done to prevent command injection. However, attackers always find smart ways to
-circumvent escaping, so we can not say if the escaping applied will really safe
-you from all hassles. Lastely, rsyslog will wait until the shell command
-terminates. Thus, a program error in it (e.g. an infinite loop) can actually
-disable rsyslog. Even without that, during the programs run-time no messages are
-processed by rsyslog. As the IP stacks buffers are quickly overflowed, this
-bears an increased risk of message loss. You must be aware of these implications.
-Even though they are severe, there are several cases where the "shell execute"
-action is very useful. This is the reason why we have included it in its current
-form. To mitigate its risks, always a) test your program thouroughly, b) make
-sure its runtime is as short as possible (if it requires a longer run-time, you
-might want to spawn your own sub-shell asynchronously), c) apply proper
-firewalling so that only known senders can send syslog messages to rsyslog.
-Point c) is especially important: if rsyslog is accepting message from any hosts,
-chances are much higher that an attacker might try to exploit the "shell execute"
-action.</p>
-<h2>TEMPLATE NAME</h2>
-<p>Every ACTION can be followed by a template name. If so, that template is used
-for message formatting. If no name is given, a hardcoded default template is
-used for the action. There can only be one template name for each given action.
-The default template is specific to each action. For a description of what a
-template is and what you can do with it, see "TEMPLATES" at the top of this
-document.</p>
-<h2>EXAMPLES</h2>
-<p>Below are example for templates and selector lines. I hope they are
-self-explanatory. If not, please see www.monitorware.com/rsyslog/ for advise.</p>
-<h3>TEMPLATES</h3>
-<p>Please note that the samples are split across multiple lines. A template MUST
-NOT actually be split across multiple lines.<br>
-<br>
-A template that resambles traditional syslogd file output:<br>
-$template TraditionalFormat,"%timegenerated% %HOSTNAME%<br>
-%syslogtag%%msg:::drop-last-lf%\n"<br>
-<br>
-A template that tells you a little more about the message:<br>
-$template precise,"%syslogpriority%,%syslogfacility%,%timegenerated%,%HOSTNAME%,<br>
-%syslogtag%,%msg%\n"<br>
-<br>
-A template for RFC 3164 format:<br>
-$template RFC3164fmt,"<%PRI%>%TIMESTAMP% %HOSTNAME% %syslogtag%%msg%"<br>
-<br>
-A template for the format traditonally used for user messages:<br>
-$template usermsg," XXXX%syslogtag%%msg%\n\r"<br>
-<br>
-And a template with the traditonal wall-message format:<br>
-$template wallmsg,"\r\n\7Message from syslogd@%HOSTNAME% at %timegenerated%<br>
-<br>
-A template that can be used for the database write (please note the SQL<br>
-template option)<br>
-$template MySQLInsert,"insert iut, message, receivedat values<br>
-('%iut%', '%msg:::UPPERCASE%', '%timegenerated:::date-mysql%')<br>
-into systemevents\r\n", SQL<br>
-<br>
-The following template emulates <a href="http://www.winsyslog.com/en/">WinSyslog</a>
-format (it's an <a href="http://www.adiscon.com/en/">Adiscon</a> format, you do
-not feel bad if you don't know it ;)). It's interesting to see how it takes
-different parts out of the date stamps. What happens is that the date stamp is
-split into the actual date and time and the these two are combined with just a
-comma in between them.<br>
-<br>
-$template WinSyslogFmt,"%HOSTNAME%,%timegenerated:1:10:date-rfc3339%,<br>
-%timegenerated:12:19:date-rfc3339%,%timegenerated:1:10:date-rfc3339%,<br>
-%timegenerated:12:19:date-rfc3339%,%syslogfacility%,%syslogpriority%,<br>
-%syslogtag%%msg%\n"</p>
-<h3>SELECTOR LINES</h3>
-<p># Store critical stuff in critical<br>
-#<br>
-*.=crit;kern.none /var/adm/critical<br>
-<br>
-This will store all messages with the priority crit in the file /var/adm/critical,
-except for any kernel message.<br>
-<br>
-<br>
-# Kernel messages are first, stored in the kernel<br>
-# file, critical messages and higher ones also go<br>
-# to another host and to the console. Messages to<br>
-# the host finlandia are forwarded in RFC 3164<br>
-# format (using the template defined above).<br>
-#<br>
-kern.* /var/adm/kernel<br>
-kern.crit @finlandia;RFC3164fmt<br>
-kern.crit /dev/console<br>
-kern.info;kern.!err /var/adm/kernel-info<br>
-<br>
-The first rule direct any message that has the kernel facility to the file /var/adm/kernel.<br>
-<br>
-The second statement directs all kernel messages of the priority crit and higher
-to the remote host finlandia. This is useful, because if the host crashes and
-the disks get irreparable errors you might not be able to read the stored
-messages. If they're on a remote host, too, you still can try to find out the
-reason for the crash.<br>
-<br>
-The third rule directs these messages to the actual console, so the person who
-works on the machine will get them, too.<br>
-<br>
-The fourth line tells rsyslogd to save all kernel messages that come with
-priorities from info up to warning in the file /var/adm/kernel-info. Everything
-from err and higher is excluded.<br>
-<br>
-<br>
-# The tcp wrapper loggs with mail.info, we display<br>
-# all the connections on tty12<br>
-#<br>
-mail.=info /dev/tty12<br>
-<br>
-This directs all messages that uses mail.info (in source LOG_MAIL | LOG_INFO) to
-/dev/tty12, the 12th console. For example the tcpwrapper tcpd(8) uses this as
-it's default.<br>
-<br>
-<br>
-# Store all mail concerning stuff in a file<br>
-#<br>
-mail.*;mail.!=info /var/adm/mail<br>
-<br>
-This pattern matches all messages that come with the mail facility, except for
-the info priority. These will be stored in the file /var/adm/mail.<br>
-<br>
-<br>
-# Log all mail.info and news.info messages to info<br>
-#<br>
-mail,news.=info /var/adm/info<br>
-<br>
-This will extract all messages that come either with mail.info or with news.info
-and store them in the file /var/adm/info.<br>
-<br>
-<br>
-# Log info and notice messages to messages file<br>
-#<br>
-*.=info;*.=notice;\<br>
-mail.none /var/log/messages<br>
-<br>
-This lets rsyslogd log all messages that come with either the info or the notice
-facility into the file /var/log/messages, except for all<br>
-messages that use the mail facility.<br>
-<br>
-<br>
-# Log info messages to messages file<br>
-#<br>
-*.=info;\<br>
-mail,news.none /var/log/messages<br>
-<br>
-This statement causes rsyslogd to log all messages that come with the info
-priority to the file /var/log/messages. But any message coming either with the
-mail or the news facility will not be stored.<br>
-<br>
-<br>
-# Emergency messages will be displayed using wall<br>
-#<br>
-*.=emerg *<br>
-<br>
-This rule tells rsyslogd to write all emergency messages to all currently logged
-in users. This is the wall action.<br>
-<br>
-<br>
-# Messages of the priority alert will be directed<br>
-# to the operator<br>
-#<br>
-*.alert root,rgerhards<br>
-<br>
-This rule directs all messages with a priority of alert or higher to the
-terminals of the operator, i.e. of the users ``root'' and ``rgerhards'' if
-they're logged in.<br>
-<br>
-<br>
-*.* @finlandia<br>
-<br>
-This rule would redirect all messages to a remote host called finlandia. This is
-useful especially in a cluster of machines where all syslog messages will be
-stored on only one machine.<br>
-<br>
-In the format shown above, UDP is used for transmitting the message. The
-destination port is set to the default auf 514. Rsyslog is also capable of using
-much more secure and reliable TCP sessions for message forwarding. Also, the
-destination port can be specified. To select TCP, simply add one additional @ in
-front of the host name (that is, @host is UPD, @@host is TCP). For example:<br>
-<br>
-<br>
-*.* @@finlandia<br>
-<br>
-To specify the destination port on the remote machine, use a colon followed by
-the port number after the machine name. The following forwards to port 1514 on
-finlandia:<br>
-<br>
-<br>
-*.* @@finlandia:1514<br>
-<br>
-This syntax works both with TCP and UDP based syslog. However, you will probably
-primarily need it for TCP, as there is no well-accepted port for this transport
-(it is non-standard). For UDP, you can usually stick with the default auf 514,
-but might want to modify it for security rea-<br>
-sons. If you would like to do that, it's quite easy:<br>
-<br>
-<br>
-*.* @finlandia:1514<br>
-<br>
-<br>
-<br>
-*.* >dbhost,dbname,dbuser,dbpassword;dbtemplate<br>
-<br>
-This rule writes all message to the database "dbname" hosted on "dbhost". The
-login is done with user "dbuser" and password "dbpassword". The actual table
-that is updated is specified within the template (which contains the insert
-statement). The template is called "dbtemplate" in this case.</p>
-<p>:msg,contains,"error" @errorServer</p>
-<p>This rule forwards all messages that contain the word "error" in the msg part
-to the server "errorServer". Forwarding is via UDP. Please note the colon in
-fron</p>
-<h2>CONFIGURATION FILE SYNTAX DIFFERENCES</h2>
-<p>Rsyslogd uses a slightly different syntax for its configuration file than the
-original BSD sources. Originally all messages of a specific priority and above
-were forwarded to the log file. The modifiers ``='', ``!'' and ``-'' were added
-to make rsyslogd more flexible and to use it in a more intuitive manner.<br>
-<br>
-The original BSD syslogd doesn't understand spaces as separators between the
-selector and the action field.<br>
-<br>
-When compared to syslogd from sysklogd package, rsyslogd offers additional
-<a href="features.html">features</a> (like template and database support). For obvious reasons, the syntax for
-defining such features is available
-in rsyslogd, only.<br>
- </p>
-</body>
+<html> +<head> +<title>rsyslog.conf file</title> +</head> +<body> +<h1>rsyslog.conf configuration file</h1> +<p><b>This document is currently being enhanced. Please pardon its current +appearance.</b></p> +<p><b>Rsyslogd is configured via the rsyslog.conf file</b>, typically found in +/etc. By default, rsyslogd reads the file /etc/rsyslog.conf.</p> +<p>While rsyslogd contains enhancements over standard syslogd, efforts have been +made to keep the configuration file as compatible as possible. While, for +obvious reasons, <a href="features.html">enhanced features</a> require a +different config file syntax, rsyslogd should be able to work with a standard +syslog.conf file. This is especially useful while you are migrating from syslogd +to rsyslogd.</p> +<h2>Basic Structure</h2> +<p>Rsyslog supports standard sysklogd's configuration file format and extends +it. So in general, you can take a "normal" syslog.conf and use it together with +rsyslogd. It will understand everything. However, to use most of rsyslogd's +unique features, you need to add extended configuration directives.<p>Rsyslogd +supports the classical, selector-based rule lines. They are still at the heart +of it and all actions are initiated via rule lines. A rule lines is any line not +starting with a $ or the comment sign (#). Lines starting with $ carry +rsyslog-specific directives.<p>Every rule line consists of two fields, a selector field and an action field. +These two fields are separated by one or more spaces or tabs. The selector field +specifies a pattern of facilities and priorities belonging to the specified +action.<br> +<br> +Lines starting with a hash mark ("#'') and empty lines are ignored. +<h2>Allowed Sender Lists</h2> +<p>Allowed sender lists can be used to specify which remote systems are allowed +to send syslog messages to rsyslogd. With them, further hurdles can be placed +between an attacker and rsyslogd. If a message from a system not in the allowed +sender list is received, that message is discarded. A diagnostic message is +logged, so that the fact is recorded (this message can be turned off with the +"-w" rsyslogd command line option).</p> +<p>Allowed sender lists can be defined for UDP and TCP senders seperately. There +can be as many allowed senders as needed. The syntax to specify them is:</p> +<p><code><b>$AllowedSender <protocol>, ip[/bits], ip[/bits]</b></code></p> +<p>"$AllowedSender" is the directive - it must be written exactly as shown and +the $ must start at the first column of the line. "<protocol>" is either "UDP" +or "TCP". It must immediately be followed by the comma, else you will receive an +error message. "ip[/bits]" is a machine or network ip address as in +"192.0.2.0/24" or "127.0.0.1". If the "/bits" part is omitted, a single host is +assumed (32 bits or mask 255.255.255.255). "/0" is not allowed, because that +would match any sending system. If you intend to do that, just remove all $AllowedSender +directives. If more than 32 bits are requested, they are adjusted to 32. +Multiple allowed senders can be specified in a comma-delimited list. Also, +multiple $AllowedSender lines can be given. They are all combined into one UDP +and one TCP list. Performance-wise, it is good to specify those allowed senders +with high traffic volume before those with lower volume. As soon as a match is +found, no further evaluation is necessary and so you can save CPU cycles.</p> +<p>Rsyslogd handles allowed sender detection very early in the code, nearly as +the first action after receiving a message. This keeps the access to potential +vulnerable code in rsyslog at a minimum. However, it is still a good idea to +impose allowed sender limitations via firewalling.</p> +<p><b>WARNING:</b> by UDP design, rsyslogd can not identify a spoofed sender +address in UDP syslog packets. As such, a malicous person could spoof the adress +of an allowed sender, send such packets to rsyslogd and rsyslogd would accept +them as being from the faked sender. To prevent this, use syslog via TCP +exclusively. If you need to use UDP-based syslog, make sure that you do proper +egress and ingress filtering at the firewall and router level.</p> +<p>An example for an allowed sender list is as follows:</p> +<p><code><b>$AllowedSender UDP, 127.0.0.1, 192.0.2.0/24</b></code></p> +<h2>Templates</h2> +<p>Templates are a key feature of rsyslog. They allow to specify any format a user +might want. They are also used for dynamic file name generation. Every output in rsyslog uses templates - this holds true for files, +user messages and so on. The database writer expects its template to be a proper +SQL statement - so this is highly customizable too. You might ask how does all +of this work when no templates at all are specified. Good question ;) The answer +is simple, though. Templates compatible with the stock syslogd formats are +hardcoded into rsyslogd. So if no template is specified, we use one of these +hardcoded templates. Search for "template_" in syslogd.c and you will find the +hardcoded ones.</p> +<p>A template consists of a template directive, a name, the actual template text +and optional options. A sample is:</p> +<blockquote><code>$template MyTemplateName,"\7Text %property% some more text\n",<options></code></blockquote> +<p>The "$template" is the template directive. It tells rsyslog that this line +contains a template. "MyTemplateName" is the template name. All +other config lines refer to this name. The text within quotes is the actual +template text. The backslash is an escape character, much as it is in C. It does +all these "cool" things. For example, \7 rings the bell (this is an ASCII +value), \n is a new line. C programmers and perl coders have the advantage of +knowing this, but the set in rsyslog is a bit restricted currently. +<p> +All text in the template is used literally, except for things within percent +signs. These are properties and allow you access to the contents of the syslog +message. Properties are accessed via the property replacer (nice name, huh) and +it can do cool things, too. For example, it can pick a substring or do +date-specific formatting. More on this is below, on some lines of the property +replacer.<br> +<br> +The <options> part is optional. It carries options influencing the template as +whole. See details below. Be sure NOT to mistake template options with property +options - the later ones are processed by the property replacer and apply to a +SINGLE property, only (and not the whole template).<br> +<br> +Template options are case-insensitive. Currently defined are: </p> +<p><b>sql</b> - format the string suitable for a SQL statement in MySQL format. This will +replace single quotes ("'") and the backslash character by their +backslash-escaped counterpart ("\'" and "\\") inside each field. Please note +that in MySQL configuration, the <code class="literal">NO_BACKSLASH_ESCAPES</code> +mode must be turned off for this format to work (this is the default).</p> +<p><b>stdsql</b> - format the string suitable for a SQL statement that is to be +sent to a standards-compliant sql server. This will +replace single quotes ("'") by two single quotes ("''") inside each field. +You must use stdsql together with MySQL if in MySQL configuration the +<code class="literal">NO_BACKSLASH_ESCAPES</code> is turned on.</p> +<p>Either the <b>sql</b> or <b>stdsql</b> +option <b>must</b> be specified when a template is used for writing to a database, +otherwise injection might occur. Please note that due to the unfortunate fact +that several vendors have violated the sql standard and introduced their own +escape methods, it is impossible to have a single option doing all the work. +So you yourself must make sure you are using the right format. <b>If you choose +the wrong one, you are still vulnerable to sql injection.</b><br> +<br> +Please note that the database writer *checks* that the sql option is present in +the template. If it is not present, the write database action is disabled. This +is to guard you against accidential forgetting it and then becoming vulnerable +to SQL injection. The sql option can also be useful with files - especially if +you want to import them into a database on another machine for performance +reasons. However, do NOT use it if you do not have a real need for it - among +others, it takes some toll on the processing time. Not much, but on a really +busy system you might notice it ;)</p> +<p>The default template for the write to database action has the sql option set. +As we currently support only MySQL and the sql option matches the default MySQL +configuration, this is a good choice. However, if you have turned on +<code class="literal">NO_BACKSLASH_ESCAPES</code> in your MySQL config, you need +to supply a template with the stdsql option. Otherwise you will become +vulnerable to SQL injection. <br> +<br> +To escape:<br> +% = \%<br> +\ = \\ --> '\' is used to escape (as in C)<br> +$template TraditionalFormat,%timegenerated% %HOSTNAME% %syslogtag%%msg%\n"<br> +<br> +Properties can be accessed by the <a href="property_replacer.html">property replacer</a> +(see there for details).</p> +<p><b>Please note that as of 1.15.0, templates can also by used to generate +selector lines with dynamic file names.</b> For example, if you would like to +split syslog messages from different hosts to different files (one per host), +you can define the following template:</p> +<blockquote><code>$template DynFile,"/var/log/system-%HOSTNAME%.log"</code></blockquote> +<p>This template can then be used when defining an output selector line. It will +result in something like "/var/log/system-localhost.log"</p> +<h2>Output Channels</h2> +<p>Output Channels are a new concept first introduced in rsyslog 0.9.0. As of this +writing, it is still unclear if they will stay in rsyslog or go away. So if you +use them, be prepared to change you configuration file syntax when you upgrade +to a later release.<br> +<br> +The idea behind output channel definitions is that it shall provide an umbrella +for any type of output that the user might want. In essence,<br> +this is the "file" part of selector lines (and this is why we are not sure +output channel syntax will stay after the next review). There is a<br> +difference, though: selector channels both have filter conditions (currently +facility and severity) as well as the output destination. Output channels define +the output defintion, only. As of this build, they can only be used to write to +files - not pipes, ttys or whatever else. If we stick with output channels, this +will change over time.</p> +<p>In concept, an output channel includes everything needed to know about an +output actions. In practice, the current implementation only carries<br> +a filename, a maximum file size and a command to be issued when this file size +is reached. More things might be present in future version, which might also +change the syntax of the directive.</p> +<p>Output channels are defined via an $outchannel directive. It's syntax is as +follows:<br> +<br> +$outchannel name,file-name,max-size,action-on-max-size<br> +<br> +name is the name of the output channel (not the file), file-name is the file +name to be written to, max-size the maximum allowed size and action-on-max-size +a command to be issued when the max size is reached.<br> +<br> +Please note that max-size is queried BEFORE writing the log message to the file. +So be sure to set this limit reasonably low so that any message might fit. For +the current release, setting it 1k lower than you expected is helpful. The +max-size must always be specified in bytes - there are no special symbols (like +1k, 1m,...) at this point of development.<br> +<br> +Keep in mind that $outchannel just defines a channel with "name". It does not +activate it. To do so, you must use a selector line (see below). That selector +line includes the channel name plus an $ sign in front of it. A sample might be:<br> +<br> +*.* $mychannel<br> +<br> +In its current form, output channels primarily provide the ability to size-limit +an output file. To do so, specify a maximum size. When this size is reachead, +rsyslogd will execute the action-on-max-size command and then reopen the file +and retry. The command should be something like a log rotation script or a +similar thing.</p> +<blockquote> + <p><b>WARNING</b> + <p>The current command logic is a quick hack. It simply issues the command via a +system() call, which is very dirty. Don't make rsyslogd a suid +binary and use action-on-max-size commands - this will mess up things. Fixing +this is on top of the todo list and the fix will hopefully +appear soon.</p> +</blockquote> +<p>If there is no action-on-max-size command or the command did not resolve the +situation, the file is closed and never reopened by rsyslogd (except, of course, +by huping it). This logic was integrated when we first experienced severe issues +with files larger 2gb, which could lead to rsyslogd dumping core. In such cases, +it is more appropriate to stop writing to a single file. Meanwhile, rsyslogd has +been fixed to support files larger 2gb, but obviously only on file systems and +operating system versions that do so. So it can still make sense to enforce a +2gb file size limit.</p> +<h2>Filter Conditions</h2> +<p>Rsyslog offers two different types "filter conditions":</p> +<ul> + <li>"traditional" severity and facility based selectors</li> + <li>property-based filters</li> +</ul> +<h3>Blocks</h3> +<p>Rsyslogd supports BSD-style blocks inside rsyslog.conf. Each block of lines +is separated from the previous block by a program or hostname specification. A +block will only log messages corresponding to the most recent program and +hostname specifications given. Thus, a block which selects ‘ppp’ as the program, +directly followed by a block that selects messages from the hostname ‘dialhost’, +then the second block will only log messages from the ppp program on dialhost. +</p> +<p>A program specification is a line beginning with ‘!prog’ and the following +blocks will be associated with calls to syslog from that specific program. A +program specification for ‘foo’ will also match any message logged by the kernel +with the prefix ‘foo: ’. A hostname specification of the form ‘+hostname’ and +the following blocks will be applied to messages received from the specified +hostname. Alternatively, a hostname specification ‘-hostname’ causes the +following blocks to be applied to messages from any host but the one specified. +If the hostname is given as ‘@’, the local hostname will be used. (NOT YET +IMPLEMENTED) A program or hostname specification may be reset by giving the +program or hostname as ‘*’.</p> +<p>Please note that the "#!prog", "#+hostname" and "#-hostname" syntax available +in BSD syslogd is not supported by rsyslogd. By default, no hostname or program +is set.</p> +<h3>Selectors</h3> +<p><b>Selectors are the traditional way of filtering syslog messages.</b> They +have been kept in rsyslog with their orginal syntax, because it is well-known, +highly effective and also needed for compatibility with stock syslogd +configuration files. If you just need to filter based on priority and facility, +you should do this with selector lines. They are <b>not</b> second-class +citicens in rsyslog and offer the best performance for this job.</p> +<p>The selector field itself again consists of two parts, a facility and a +priority, separated by a period (``.''). Both parts are case insenstive and can +also be specified as decimal numbers, but don't do that, you have been warned. +Both facilities and priorities are described in rsyslog(3). The names mentioned +below correspond to the similar LOG_-values in /usr/include/rsyslog.h.<br><br>The facility is one of the following keywords: auth, authpriv, cron, daemon, +kern, lpr, mail, mark, news, security (same as auth), syslog, user, uucp and +local0 through local7. The keyword security should not be used anymore and mark +is only for internal use and therefore should not be used in applications. +Anyway, you may want to specify and redirect these messages here. The facility +specifies the subsystem that produced the message, i.e. all mail programs log +with the mail facility (LOG_MAIL) if they log using syslog.<br><br>Please note that the upcoming next syslog-RFC specifies many more facilities. +Support for them will be added in a future version of rsyslog, which might +require changes to existing configuration files.<br><br>The priority is one of the following keywords, in ascending order: debug, info, +notice, warning, warn (same as warning), err, error (same as err), crit, alert, +emerg, panic (same as emerg). The keywords error, warn and panic are deprecated +and should not be used anymore. The priority defines the severity of the message<br> +<br>The behavior of the original BSD syslogd is that all messages of the specified +priority and higher are logged according to the given action. Rsyslogd behaves the same, but has some extensions.<br><br>In addition to the above mentioned names the rsyslogd(8) understands the +following extensions: An asterisk (``*'') stands for all facilities or all +priorities, depending on where it is used (before or after the period). The +keyword none stands for no priority of the given facility.<br><br>You can specify multiple facilities with the same priority pattern in one +statement using the comma (``,'') operator. You may specify as much facilities +as you want. Remember that only the facility part from such a statement is +taken, a priority part would be skipped.</p> +<p>Multiple selectors may be specified for a single action using the semicolon +(``;'') separator. Remember that each selector in the selector field is capable +to overwrite the preceding ones. Using this behavior you can exclude some +priorities from the pattern.</p> +<p>Rsyslogd has a syntax extension to the original BSD source, that makes its +use more intuitively. You may precede every priority with an equation sign +(``='') to specify only this single priority and not any of the above. You may +also (both is valid, too) precede the priority with an exclamation mark (``!'') +to ignore all that priorities, either exact this one or this and any higher +priority. If you use both extensions than the exclamation mark must occur before +the equation sign, just use it intuitively.</p> +<h3>Property-Based Filters</h3> +<p>Property-based filters are unique to rsyslogd. They allow to filter on any +property, like HOSTNAME, syslogtag and msg. A list of all currently-supported +properties can be found in the <a href="property_replacer.html">property +replacer documentation</a> (but keep in mind that only the properties, not the +replacer is supported). With this filter, each properties can be checked against +a specified value, using a specified compare operation. Currently, there is only +a single compare operation (contains) available, but additional operations will be added in the +future.</p> +<p>A property-based filter must start with a colon in column 0. This tells +rsyslogd that it is the new filter type. The colon must be followed by the +property name, a comma, the name of the compare operation to carry out, another +comma and then the value to compare against. This value must be quoted. There +can be spaces and tabs between the commas. Property names and compare operations +are case-sensitive, so "msg" works, while "MSG" is an invalid property name. In +brief, the syntax is as follows:</p> +<p><code><b>:property, [!]compare-operation, "value"</b></code></p> +<p>The following <b>compare-operations</b> are currently supported:</p> +<table border="1" width="100%" id="table1"> + <tr> + <td>contains</td> + <td>Checks if the string provided in value is contained in the property. + There must be an exact match, wildcards are not supported.</td> + </tr> + <tr> + <td>isequal</td> + <td>Compares the "value" string provided and the property contents. + These two values must be exactly equal to match. The difference to + contains is that contains searchs for the value anywhere inside the + property value, whereas all characters must be identical for isequal. As + such, isequal is most useful for fields like syslogtag or FROMHOST, + where you probably know the exact contents.</td> + </tr> + <tr> + <td>startswith</td> + <td>Checks if the value is found exactly at the beginning of the + property value. For example, if you search for "val" with<p><code><b>:msg, + startswith, "val"</b></code></p> + <p>it will be a match if msg contains "values are in this message" but + it won't match if the msg contains "There are values in this message" + (in the later case, contains would match). Please note that "startswith" + is by far faster than regular expressions. So even once they are + implemented, it can make very much sense (performance-wise) to use "startswith".</td> + </tr> + <tr> + <td>regex</td> + <td><b>NOT YET IMPLEMENTED</b> - value holds an regular expression</td> + </tr> +</table> +<p>You can use the bang-character (!) immediately in front of a +compare-operation, the outcome of this operation is negated. For example, if msg +contains "This is an informative message", the following sample would not match:</p> +<p><code><b>:msg, contains, "error"</b></code></p> +<p>but this one matches:</p> +<p><code><b>:msg, !contains, "error"</b></code></p> +<p>Using negation can be useful if you would like to do some generic processing +but exclude some specific events. You can use the discard action in conjunction +with that. A sample would be:</p> +<p><code><b>*.* /var/log/allmsgs-including-informational.log<br> +:msg, contains, "informational" <font color="#FF0000" size="4">~</font> +<br>*.* /var/log/allmsgs-but-informational.log</b></code></p> +<p>Do not overlook the red tilde in line 2! In this sample, all messages are +written to the file allmsgs-including-informational.log. Then, all messages +containing the string "informational" are discarded. That means the config file +lines below the "discard line" (number 2 in our sample) will not be applied to +this message. Then, all remaining lines will also be written to the file +allmsgs-but-informational.log.</p> +<p><b>Value</b> is a quoted string. It supports some escape sequences:</p> +<p>\" - the quote character (e.g. "String with \"Quotes\"")<br> +\\ - the backslash character (e.g. "C:\\tmp")</p> +<p>Escape sequences always start with a backslash. Additional escape sequences +might be added in the future. Backslash characters <b>must</b> be escaped. Any +other sequence then those outlined above is invalid and may lead to +unpredictable results.</p> +<p>Probably, "msg" is the most prominent use case of property based filters. It +is the actual message text. If you would like to filter based on some message +content (e.g. the presence of a specific code), this can be done easily by:</p> +<p><code><b>:msg, contains, "ID-4711"</b></code></p> +<p>This filter will match when the message contains the string "ID-4711". Please +note that the comparison is case-sensitive, so it would not match if "id-4711" +would be contained in the message.</p> +<p>Getting property-based filters right can sometimes be challenging. In order +to help you do it with as minimal effort as possible, rsyslogd spits out debug +information for all property-based filters during their evaluation. To enable +this, run rsyslogd in foreground and specify the "-d" option.</p> +<p>Boolean operations inside property based filters (like 'message contains +"ID17" or message contains "ID18"') are currently not supported +(except for "not" as outlined above). Please note +that while it is possible to query facility and severity via property-based filters, +it is far more advisable to use classic selectors (see above) for those +cases.</p> +<h2>ACTIONS</h2> +<p>The action field of a rule describes what to do with the message. In general, +message content is written to a kind of "logfile". But also other actions might +be done, like writing to a database table or forwarding to another host.<br> +<br> +Templates can be used with all actions. If used, the specified template is used +to generate the message content (instead of the default template). To specify a +template, write a semicolon after the action value immediately followed by the +template name.<br> +<br> +Beware: templates MUST be defined BEFORE they are used. It is OK to define some +templates, then use them in selector lines, define more templates and use use +them in the following selector lines. But it is NOT permitted to use a template +in a selectore line that is above its definition. If you do this, the selector +line will be ignored.</p> +<h3>Regular File</h3> +<p>Typically messages are logged to real files. The file has to be specified with +full pathname, beginning with a slash "/''.<br> +<br> +You may prefix each entry with the minus ``-'' sign to omit syncing the file +after every logging. Note that you might lose information if the system crashes +right behind a write attempt. Nevertheless this might give you back some +performance, especially if you run programs that use +logging in a very verbose manner.</p> +<p>If your system is connected to a reliable UPS and you receive lots of log +data (e.g. firewall logs), it might be a very good idea to turn of +syncing by specifying the "-" in front of the file name. </p> +<p><b>The filename can be either static </b>(always the same) or <b>dynamic</b> +(different based on message received). The later is useful if you would +automatically split messages into different files based on some message +criteria. For example, dynamic file name selectors allow you to split messages +into different files based on the host that sent them. With dynamic file names, +everything is automatic and you do not need any filters. </p> +<p>It works via the template system. First, you define a template for the file +name. An example can be seen above in the description of template. We will use +the "DynFile" template defined there. Dynamic filenames are indicated by +specifying a questions mark "?" instead of a slash, followed by the template +name. Thus, the selector line for our dynamic file name would look as follows:</p> +<p align="center"> +<code>*.* ?DynFile</code> +</p> +<p>That's all you need to do. Rsyslog will now automatically generate file names +for you and store the right messages into the right files.</p> +<p><b>A word of caution:</b> rsyslog creates files as needed. So if a new host +is using your syslog server, rsyslog will automatically create a new file for +it. <b>However, directories are never created</b>. So if you use a dynamic +directory name, you must make sure that all possible directories are created, +otherwise the writes will fail. This restriction will most probably be removed +in later versions of rsyslogd.</p> +<h3>Named Pipes</h3> +<p>This version of rsyslogd(8) has support for logging output to named pipes (fifos). +A fifo or named pipe can be used as a destination for log messages by prepending +a pipe symbol (``|'') to the name of the file. This is handy for debugging. Note +that the fifo must be created with the mkfifo(1) command before rsyslogd(8) is +started.</p> +<h3>Terminal and Console</h3> +<p>If the file you specified is a tty, special tty-handling is done, same with +/dev/console.</p> +<h3>Remote Machine</h3> +<p>Rsyslogd provides full remote logging, i.e. is able to send messages to a +remote host running rsyslogd(8) and to receive messages from remote hosts. +Using this feature you're able to control all syslog messages on one host, if +all other machines will log remotely to that. This tears down<br> +administration needs.<br> +<br> +<b>Please note that this version of rsyslogd by default does NOT forward messages +it has received from the network to another host. Specify the "-h" option to enable this.</b></p> +<p>To forward messages to another host, prepend the hostname with the at sign ("@"). +A single at sign means that messages will be forwarded via UDP protocol (the +standard for syslog). If you prepend two at signs ("@@"), the messages will be +transmitted via TCP. Please note that plain TCP based syslog is not officially +standardized, but most major syslogds support it (e.g. syslog-ng or WinSyslog). +The forwarding action indicator (at-sign) can be followed by one or more options. +If they are given, they must be immediately (without a space) following the +final at sign and be enclosed in parenthesis. The individual options must be +separated by commas. The following options are right now defined:</p> +<table border="1" width="100%" id="table2"> + <tr> + <td> + <p align="center"><b>z<number></b></td> + <td>Enable zlib-compression for the message. The <number> is the + compression level. It can be 1 (lowest gain, lowest CPU overhead) to 9 (maximum + compression, highest CPU overhead). The level can also be 0, which means + "no compression". If given, the "z" option is ignored. So this does not + make an awful lot of sense. There is hardly a difference between level 1 + and 9 for typical syslog messages. You can expect a compression gain + between 0% and 30% for typical messages. Very chatty messages may + compress up to 50%, but this is seldomly seen with typicaly traffic. + Please note that rsyslogd checks the compression gain. Messages with 60 + bytes or less will never be compressed. This is because compression gain + is pretty unlikely and we prefer to save CPU cycles. Messags over that + size are always compressed. However, it is checked if there is a gain in + compression and only if there is, the compressed message is transmitted. + Otherwise, the uncompressed messages is transmitted. This saves the + receiver CPU cycles for decompression. It also prevents small message to + actually become larger in compressed form.<p><b>Please note that when a + TCP transport is used, compression will also turn on + syslog-transport-tls framing. See the "o" option for important + information on the implications.</b></p> + <p>Compressed messages are automatically detected and decompressed by + the receiver. There is nothing that needs to be configured on the + receiver side.</td> + </tr> + <tr> + <td> + <p align="center"><b>o</b></td> + <td><b>This option is experimental. Use at your own risk and only if you + know why you need it! If in doubt, do NOT turn it on.</b><p>This option + is only valid for plain TCP based transports. It selects a different + framing based on IETF internet draft syslog-transport-tls-06. This + framing offers some benefits over traditional LF-based framing. However, + the standardization effort is not yet complete. There may be changes in + upcoming versions of this standard. Rsyslog will be kept in line with + the standard. There is some chance that upcoming changes will be + incompatible to the current specification. In this case, all systems + using -transport-tls framing must be upgraded. There will be no effort + made to retain compatibility between different versions of rsyslog. The + primary reason for that is that it seems technically impossible to + provide compatibility between some of those changes. So you should take + this note very serious. It is not something we do not *like* to do (and + may change our mind if enough pepole beg...), it is something we most + probably *can not* do for technical reasons (aka: you can beg as much as + you like, it won't change anything...).</p> + <p>The most important implication is that compressed syslog messages via + TCP must be considered with care. Unfortunately, it is technically + impossible to transfer compressed records over traditional syslog plain + tcp transports, so you are left with two evil choices...</td> + </tr> +</table> +<p><br> +The hostname may be followed by a colon and the destination port.</p> +<p>The following is an example selector line with forwarding:</p> +<p>*.* @@(o,z9)192.168.0.1:1470</p> +<p>In this example, messages are forwarded via plain TCP with experimental +framing and maximum compression to the host 192.168.0.1 at port 1470.</p> +<p>*.* @192.168.0.1</p> +<p>In the example above, messages are forwarded via UDP to the machine +192.168.0.1, the destination port defaults to 514. Messages will not be +compressed.</p> +<h3>List of Users</h3> +<p>Usually critical messages are also directed to ``root'' on that machine. You can +specify a list of users that shall get the message by simply writing the login. +You may specify more than one user by separating them with commas (",''). If +they're logged in they get the message. Don't think a mail would be sent, that +might be too late.</p> +<h3>Everyone logged on</h3> +<p>Emergency messages often go to all users currently online to notify them that +something strange is happening with the system. To specify this wall(1)-feature +use an asterisk ("*'').</p> +<h3>Database Table</h3> +<p>This allows logging of the message to a database table. Currently, only MySQL +databases are supported. By default, a MonitorWare-compatible schema is required +for this to work. You can create that schema with the createDB.SQL file that +came with the rsyslog package. You can also<br> +use any other schema of your liking - you just need to define a proper template +and assign this template to the action.<br> +<br> +The database writer is called by specifying a greater-then sign (">") in front +of the database connect information. Immediately after that<br> +sign the database host name must be given, a comma, the database name, another +comma, the database user, a comma and then the user's password. If a specific +template is to be used, a semicolong followed by the template name can follow +the connect information. This is as follows:<br> +<br> +>dbhost,dbname,dbuser,dbpassword;dbtemplate</p> +<h3>Discard</h3> +<p>If the discard action is carried out, the received message is immediately +discarded. No further processing of it occurs. Discard has primarily been added +to filter out messages before carrying on any further processing. For obvious +reasons, the results of "discard" are depending on where in the configuration +file it is being used. Please note that once a message has been discarded there +is no way to retrive it in later configuration file lines.</p> +<p>Discard can be highly effective if you want to filter out some annoying +messages that otherwise would fill your log files. To do that, place the discard +actions early in your log files. This often plays well with property-based +filters, giving you great freedom in specifying what you do not want.</p> +<p>Discard is just the single tilde character with no further parameters:</p> +<p>~</p> +<p>For example,</p> +<p>*.* ~</p> +<p>discards everything (ok, you can achive the same by not running rsyslogd at +all...).</p> +<h3>Output Channel</h3> +<p>Binds an output channel definition (see there for details) to this action. +Output channel actions must start with a $-sign, e.g. if you would like to bind +your output channel definition "mychannel" to the action, use "$mychannel". +Output channels support template definitions like all all other actions.</p> +<h3>Shell Execute</h3> +<p>This executes a program in a subshell. The programm is passed the +template-generated message as the only command line parameter. Rsyslog waits +until the program terminates and only then continues to run.</p> +<p>^programm-to-execute;template</p> +<p>The program-to-execute can be any valid executable.</p> +<p><b>WARNING:</b> The Shell Execute action was added to serve an urgent need. +While it is considered reasonable save when used with some thinking, its +implications must be considered. The current implementation uses a system() call +to execute the command. This is not the best way to do it (and will hopefully +changed in further releases). Also, proper escaping of special characters is +done to prevent command injection. However, attackers always find smart ways to +circumvent escaping, so we can not say if the escaping applied will really safe +you from all hassles. Lastely, rsyslog will wait until the shell command +terminates. Thus, a program error in it (e.g. an infinite loop) can actually +disable rsyslog. Even without that, during the programs run-time no messages are +processed by rsyslog. As the IP stacks buffers are quickly overflowed, this +bears an increased risk of message loss. You must be aware of these implications. +Even though they are severe, there are several cases where the "shell execute" +action is very useful. This is the reason why we have included it in its current +form. To mitigate its risks, always a) test your program thouroughly, b) make +sure its runtime is as short as possible (if it requires a longer run-time, you +might want to spawn your own sub-shell asynchronously), c) apply proper +firewalling so that only known senders can send syslog messages to rsyslog. +Point c) is especially important: if rsyslog is accepting message from any hosts, +chances are much higher that an attacker might try to exploit the "shell execute" +action.</p> +<h2>TEMPLATE NAME</h2> +<p>Every ACTION can be followed by a template name. If so, that template is used +for message formatting. If no name is given, a hardcoded default template is +used for the action. There can only be one template name for each given action. +The default template is specific to each action. For a description of what a +template is and what you can do with it, see "TEMPLATES" at the top of this +document.</p> +<h2>EXAMPLES</h2> +<p>Below are example for templates and selector lines. I hope they are +self-explanatory. If not, please see www.monitorware.com/rsyslog/ for advise.</p> +<h3>TEMPLATES</h3> +<p>Please note that the samples are split across multiple lines. A template MUST +NOT actually be split across multiple lines.<br> +<br> +A template that resambles traditional syslogd file output:<br> +$template TraditionalFormat,"%timegenerated% %HOSTNAME%<br> +%syslogtag%%msg:::drop-last-lf%\n"<br> +<br> +A template that tells you a little more about the message:<br> +$template precise,"%syslogpriority%,%syslogfacility%,%timegenerated%,%HOSTNAME%,<br> +%syslogtag%,%msg%\n"<br> +<br> +A template for RFC 3164 format:<br> +$template RFC3164fmt,"<%PRI%>%TIMESTAMP% %HOSTNAME% %syslogtag%%msg%"<br> +<br> +A template for the format traditonally used for user messages:<br> +$template usermsg," XXXX%syslogtag%%msg%\n\r"<br> +<br> +And a template with the traditonal wall-message format:<br> +$template wallmsg,"\r\n\7Message from syslogd@%HOSTNAME% at %timegenerated%<br> +<br> +A template that can be used for the database write (please note the SQL<br> +template option)<br> +$template MySQLInsert,"insert iut, message, receivedat values<br> +('%iut%', '%msg:::UPPERCASE%', '%timegenerated:::date-mysql%')<br> +into systemevents\r\n", SQL<br> +<br> +The following template emulates <a href="http://www.winsyslog.com/en/">WinSyslog</a> +format (it's an <a href="http://www.adiscon.com/en/">Adiscon</a> format, you do +not feel bad if you don't know it ;)). It's interesting to see how it takes +different parts out of the date stamps. What happens is that the date stamp is +split into the actual date and time and the these two are combined with just a +comma in between them.<br> +<br> +$template WinSyslogFmt,"%HOSTNAME%,%timegenerated:1:10:date-rfc3339%,<br> +%timegenerated:12:19:date-rfc3339%,%timegenerated:1:10:date-rfc3339%,<br> +%timegenerated:12:19:date-rfc3339%,%syslogfacility%,%syslogpriority%,<br> +%syslogtag%%msg%\n"</p> +<h3>SELECTOR LINES</h3> +<p># Store critical stuff in critical<br> +#<br> +*.=crit;kern.none /var/adm/critical<br> +<br> +This will store all messages with the priority crit in the file /var/adm/critical, +except for any kernel message.<br> +<br> +<br> +# Kernel messages are first, stored in the kernel<br> +# file, critical messages and higher ones also go<br> +# to another host and to the console. Messages to<br> +# the host finlandia are forwarded in RFC 3164<br> +# format (using the template defined above).<br> +#<br> +kern.* /var/adm/kernel<br> +kern.crit @finlandia;RFC3164fmt<br> +kern.crit /dev/console<br> +kern.info;kern.!err /var/adm/kernel-info<br> +<br> +The first rule direct any message that has the kernel facility to the file /var/adm/kernel.<br> +<br> +The second statement directs all kernel messages of the priority crit and higher +to the remote host finlandia. This is useful, because if the host crashes and +the disks get irreparable errors you might not be able to read the stored +messages. If they're on a remote host, too, you still can try to find out the +reason for the crash.<br> +<br> +The third rule directs these messages to the actual console, so the person who +works on the machine will get them, too.<br> +<br> +The fourth line tells rsyslogd to save all kernel messages that come with +priorities from info up to warning in the file /var/adm/kernel-info. Everything +from err and higher is excluded.<br> +<br> +<br> +# The tcp wrapper loggs with mail.info, we display<br> +# all the connections on tty12<br> +#<br> +mail.=info /dev/tty12<br> +<br> +This directs all messages that uses mail.info (in source LOG_MAIL | LOG_INFO) to +/dev/tty12, the 12th console. For example the tcpwrapper tcpd(8) uses this as +it's default.<br> +<br> +<br> +# Store all mail concerning stuff in a file<br> +#<br> +mail.*;mail.!=info /var/adm/mail<br> +<br> +This pattern matches all messages that come with the mail facility, except for +the info priority. These will be stored in the file /var/adm/mail.<br> +<br> +<br> +# Log all mail.info and news.info messages to info<br> +#<br> +mail,news.=info /var/adm/info<br> +<br> +This will extract all messages that come either with mail.info or with news.info +and store them in the file /var/adm/info.<br> +<br> +<br> +# Log info and notice messages to messages file<br> +#<br> +*.=info;*.=notice;\<br> +mail.none /var/log/messages<br> +<br> +This lets rsyslogd log all messages that come with either the info or the notice +facility into the file /var/log/messages, except for all<br> +messages that use the mail facility.<br> +<br> +<br> +# Log info messages to messages file<br> +#<br> +*.=info;\<br> +mail,news.none /var/log/messages<br> +<br> +This statement causes rsyslogd to log all messages that come with the info +priority to the file /var/log/messages. But any message coming either with the +mail or the news facility will not be stored.<br> +<br> +<br> +# Emergency messages will be displayed using wall<br> +#<br> +*.=emerg *<br> +<br> +This rule tells rsyslogd to write all emergency messages to all currently logged +in users. This is the wall action.<br> +<br> +<br> +# Messages of the priority alert will be directed<br> +# to the operator<br> +#<br> +*.alert root,rgerhards<br> +<br> +This rule directs all messages with a priority of alert or higher to the +terminals of the operator, i.e. of the users ``root'' and ``rgerhards'' if +they're logged in.<br> +<br> +<br> +*.* @finlandia<br> +<br> +This rule would redirect all messages to a remote host called finlandia. This is +useful especially in a cluster of machines where all syslog messages will be +stored on only one machine.<br> +<br> +In the format shown above, UDP is used for transmitting the message. The +destination port is set to the default auf 514. Rsyslog is also capable of using +much more secure and reliable TCP sessions for message forwarding. Also, the +destination port can be specified. To select TCP, simply add one additional @ in +front of the host name (that is, @host is UPD, @@host is TCP). For example:<br> +<br> +<br> +*.* @@finlandia<br> +<br> +To specify the destination port on the remote machine, use a colon followed by +the port number after the machine name. The following forwards to port 1514 on +finlandia:<br> +<br> +<br> +*.* @@finlandia:1514<br> +<br> +This syntax works both with TCP and UDP based syslog. However, you will probably +primarily need it for TCP, as there is no well-accepted port for this transport +(it is non-standard). For UDP, you can usually stick with the default auf 514, +but might want to modify it for security rea-<br> +sons. If you would like to do that, it's quite easy:<br> +<br> +<br> +*.* @finlandia:1514<br> +<br> +<br> +<br> +*.* >dbhost,dbname,dbuser,dbpassword;dbtemplate<br> +<br> +This rule writes all message to the database "dbname" hosted on "dbhost". The +login is done with user "dbuser" and password "dbpassword". The actual table +that is updated is specified within the template (which contains the insert +statement). The template is called "dbtemplate" in this case.</p> +<p>:msg,contains,"error" @errorServer</p> +<p>This rule forwards all messages that contain the word "error" in the msg part +to the server "errorServer". Forwarding is via UDP. Please note the colon in +fron</p> +<h2>CONFIGURATION FILE SYNTAX DIFFERENCES</h2> +<p>Rsyslogd uses a slightly different syntax for its configuration file than the +original BSD sources. Originally all messages of a specific priority and above +were forwarded to the log file. The modifiers ``='', ``!'' and ``-'' were added +to make rsyslogd more flexible and to use it in a more intuitive manner.<br> +<br> +The original BSD syslogd doesn't understand spaces as separators between the +selector and the action field.<br> +<br> +When compared to syslogd from sysklogd package, rsyslogd offers additional +<a href="features.html">features</a> (like template and database support). For obvious reasons, the syntax for +defining such features is available +in rsyslogd, only.<br> + </p> +</body> </html>
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