The mqtt() destination has the following options.
Required options: address(), fallback-topic(), and topic().
address()
| Type: |
string |
| Default: |
tcp://localhost:1883 |
Description: Required option. Specifies the hostname or IP address, and the port number of the MQTT broker to which syslog-ng OSE will send the log messages.
Syntax: <protocol type>://<host>:<port>
NOTE: The current implementation of the mqtt() destination supports the tcp and ws transports. TLS-based addresses (that is, ssl:// or wss://) are not supported.
fallback-topic()
| Type: |
string |
| Default: |
N/A |
Description: Required option when using templates in the topic() option.
If the resolved topic() template is not a valid topic, syslog-ng OSE will use the fallback-topic() option to send messages.
NOTE: If instead of strings, you use actual templates (that is, a macro like ${MESSAGE}, or a template function like $(format-json)) in the topic() option, configuring the fallback-topic() option is required.
TIP: Occasionally, the reason why syslog-ng OSE cannot post messages to the configured topic() is that the topic contains invalid characters that originate from templates.
keep-alive()
| Type: |
positive integer number (in seconds) |
| Default: |
60 |
Description: Specifies the number of seconds that syslog-ng OSE keeps the connection between the broker and clients open in case there is no message traffic. When keep-alive() number of seconds pass, the connection is terminated, and you have to reconnect.
On the MQTT side, the keep alive function provides a workaround method to access connections that are still open.
qos()
| Type: |
number |
| Default: |
0 |
|
Possible values: |
0 - at most once (the fastest option)
1 - at least once (a much slower option than 0)
2 - exactly once (the slowest option)
|
Description: The Quality of Service (QoS) level in MQTT messaging is an agreement between sender and receiver on the guarantee of delivering a message.
template()
| Type: |
string |
| Default: |
$ISODATE $HOST $MSGHDR$MSG |
Description: Specifies the message template that syslog-ng OSE sends to the MQTT broker.
If you want to use macros in templates, see Macros of syslog-ng OSE.
topic()
| Type: |
string or template |
| Default: |
N/A |
Description: Required option. Specifies the MQTT topic.
NOTE: The current implementation of the mqtt() destination does not support using the following characters for topic names:
While using the mqtt() destination, you may encounter issues and corresponding error messages originating from the MQTT system. The following table contains the error messages you may encounter, the possible reasons behind them, and potential workaround methods.
"ERROR, while init threaded dest. ..."
|
The syslog-ng OSE application will not start.
|
You can try the following methods:
-
Restart syslog-ng OSE.
-
Stop some of the programs running on your computer.
-
Restart your computer, and then restart syslog-ng OSE.
|
"mqtt: the topic() argument is required for mqtt destinations. ..."
|
The topic() option is not set in your configuration. The syslog-ng OSE application will not start. |
Set the missing topic() option in your configuration, then restart .
|
"The mqtt destination does not support the batching of messages, ..."
|
Your configuration may contain the batch-timeout() and / or batch-lines() options, which are not supported by the mqtt() destination. The syslog-ng OSE application will not start.
|
If your configuration contains the batch-timeout() and / or batch-lines() options, remove them from your configuration, and restart .
|
"Disconnected during publish!"
|
The syslog-ng OSE application can not send the message, because syslog-ng OSE disconnected from the broker. By default, syslog-ng OSE attempts to reconnect to the broker and send the messages 3 times.
|
If syslog-ng OSE fails all 3 attempts to reconnect to the broker and send the messages, you can try checking your configuration or restarting your MQTT system with syslog-ng OSE as a client.
|
"Max message inflight! (publish)"
|
The syslog-ng OSE application can not send the message due to the max message inflight broker response code (which signals that the broker has received too many messages, and it needs more time to process them). The syslog-ng OSE application will attempt to resend the message.
|
Wait until the broker can process the in-flight messages and syslog-ng OSE can attempt to resend the message.
|
"Failure during publishing!"
|
The syslog-ng OSE application can not send the message due to the failure broker response code. The syslog-ng OSE application will attempt to resend the message.
|
N/A
|
"Error during publish!"
|
The syslog-ng OSE application can not send the message, and drops it.
Possible reason: bad_utf8_string (topic), NULL parameter.
That is, the most probable reasons behind this issue are either that the topic name in your configuration is not correct, or that the message field is empty. |
You can try the following methods:
|
"Disconnected while waiting the response!"
|
The syslog-ng OSE application has sent the message, but the client disconnected from the broker before syslog-ng OSE received the response. The syslog-ng OSE application will attempt to reconnect, or to resend the message. |
The syslog-ng OSE application will attempt to reconnect to the broker and send the in-flight message. If the reconnect attempt fails, syslog-ng OSE will resend the message. |
"Error while waiting the response!"
|
The syslog-ng OSE application can not get any response from the broker, due to the failure broker response code. The syslog-ng OSE will attempt to resend the message. |
In this case, you will receive a further error message, depending on what the problem is. Wait for the second error message for more information about how you can proceed. |
"Error constructing topic ..."
|
Due to an issue with the configured topic template, the mqtt() destination will use the fallback-topic() option instead.
|
N/A |
"mqtt dest: topic name is illegal, it can't be empty"
|
This error message is related to the "Error constructing topic ..." error message.
In this case, the topic template returns a 0 length string. As a result, the mqtt() destination will use the fallback-topic() option instead. |
N/A |
"Error connecting mqtt client ..."
|
The syslog-ng OSE application can not connect to broker, and it will attempt to reconnect later. |
If the issue persists, you can try the following:
|
"Error creat mqtt client ..."
|
The syslog-ng OSE application encountered an error while creating the MQTT client, and it will attempt to create it later.
Possible reasons:
|
You can try the following methods:
-
Check the address() option in your configuration, and modify if necessary.
-
Check if the specified broker is running by connecting to it manually, and then sending the broker a message. |
The network() destination driver can send syslog messages conforming to RFC3164 from the network using the TCP, TLS, and UDP networking protocols.
-
UDP is a simple datagram oriented protocol, which provides "best effort service" to transfer messages between hosts. It may lose messages, and no attempt is made to retransmit lost messages. The BSD-syslog protocol traditionally uses UDP.
Use UDP only if you have no other choice.
-
TCP provides connection-oriented service: the client and the server establish a connection, each message is acknowledged, and lost packets are resent. TCP can detect lost connections, and messages are lost, only if the TCP connection breaks. When a TCP connection is broken, messages that the client has sent but were not yet received on the server are lost.
-
The syslog-ng application supports TLS (Transport Layer Security, also known as SSL) over TCP. For details, see Encrypting log messages with TLS.
Declaration:
network("<destination-address>" [options]);
The network() destination has a single required parameter that specifies the destination host address where messages should be sent. If name resolution is configured, you can use the hostname of the target server. By default, syslog-ng OSE sends messages using the TCP protocol to port 514.
Example: Using the network() driver
TCP destination that sends messages to 10.1.2.3, port 1999:
destination d_tcp { network("10.1.2.3" port(1999)); };
If name resolution is configured, you can use the hostname of the target server as well.
destination d_tcp { network("target_host" port(1999)); };
TCP destination that sends messages to the ::1 IPv6 address, port 2222.
destination d_tcp6 {
network(
"::1"
port(2222)
transport(tcp)
ip-protocol(6)
);
};
To send messages using the IETF-syslog message format without using the IETF-syslog protocol, enable the syslog-protocol flag. (For details on how to use the IETF-syslog protocol, see syslog() destination options.)
destination d_tcp { network("10.1.2.3" port(1999) flags(syslog-protocol) ); };
The network() driver sends messages to a remote host (for example, a syslog-ng server or relay) on the local intranet or internet using the RFC3164 syslog protocol (for details about the protocol, see BSD-syslog or legacy-syslog messages). The network() driver supports sending messages using the UDP, TCP, or the encrypted TLS networking protocols.
These destinations have the following options:
ca-dir()
| Accepted values: |
Directory name |
| Default: |
none |
Description: The name of a directory that contains a set of trusted CA certificates in PEM format. The CA certificate files have to be named after the 32-bit hash of the subject's name. This naming can be created using the c_rehash utility in openssl. For an example, see Configuring TLS on the syslog-ng clients. The syslog-ng OSE application uses the CA certificates in this directory to validate the certificate of the peer.
This option can be used together with the optional ca-file() option.
ca-file()
| Accepted values: |
File name |
| Default: |
empty |
Description: Optional. The name of a file that contains a set of trusted CA certificates in PEM format. The syslog-ng OSE application uses the CA certificates in this file to validate the certificate of the peer.
Example format in configuration:
ca-file("/etc/pki/tls/certs/ca-bundle.crt")
NOTE: The ca-file() option can be used together with the ca-dir() option, and it is relevant when peer-verify() is set to other than no or optional-untrusted.
close-on-input()
| Type: |
yes|no |
| Default: |
yes |
Description: By default, syslog-ng OSE closes destination sockets if it receives any input from the socket (for example, a reply). If this option is set to no, syslog-ng OSE just ignores the input, but does not close the socket.
disk-buffer()
Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:
| reliable() |
| Type: |
yes|no |
| Default: |
no |
|
Description: If set to yes, syslog-ng OSE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng OSE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.
|
|
Caution:
Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost. | |
| compaction() |
| Type: |
yes|no |
| Default: |
no |
|
Description: If set to yes, syslog-ng OSE prunes the unused space in the LogMessage representation, making the disk queue size smaller at the cost of some CPU time. Setting the compaction() argument to yes is recommended when numerous name-value pairs are unset during processing, or when the same names are set multiple times. |
NOTE: Simply unsetting these name-value pairs by using the unset() rewrite operation is not enough, as due to performance reasons that help when syslog-ng is CPU bound, the internal representation of a LogMessage will not release the memory associated with these name-value pairs. In some cases, however, the size of this overhead becomes significant (the raw message size can grow up to four times its original size), which unnecessarily increases the disk queue file size. For these cases, the compaction will drop "unset" values, making the LogMessage representation smaller at the cost of some CPU time required to perform compaction.
| dir() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the folder where the disk-buffer files are stored.
|
|
Caution:
When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file.
syslog-ng OSE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, syslog-ng OSE will look for or create disk-buffer files in their old location. To ensure that syslog-ng OSE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to. | |
| disk-buf-size() |
| Type: |
number (bytes) |
| Default: |
|
| Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option. |
| mem-buf-length() |
| Type: |
number (messages) |
| Default: |
10000 |
| Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes. |
| mem-buf-size() |
| Type: |
number (bytes) |
| Default: |
163840000 |
| Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no. |
| qout-size() |
| Type: |
number (messages) |
| Default: |
64 |
| Description: The number of messages stored in the output buffer of the destination. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty. |
Options reliable() and disk-buf-size() are required options.
Example: Examples for using disk-buffer()
In the following case reliable disk-buffer() is used.
destination d_demo {
network(
"127.0.0.1"
port(3333)
disk-buffer(
mem-buf-size(10000)
disk-buf-size(2000000)
reliable(yes)
dir("/tmp/disk-buffer")
)
);
};
In the following case normal disk-buffer() is used.
destination d_demo {
network(
"127.0.0.1"
port(3333)
disk-buffer(
mem-buf-length(10000)
disk-buf-size(2000000)
reliable(no)
dir("/tmp/disk-buffer")
)
);
};
failover()
Description: Available only in syslog-ng Open Source Edition version 3.17 and later. For details about how client-side failover works, see Client-side failover.
| servers() |
| Type: |
list of IP addresses and fully-qualified domain names |
| Default: |
empty |
|
Description: Specifies a secondary destination server where log messages are sent if the primary server becomes inaccessible. To list several failover servers, separate the address of the servers with comma. By default, syslog-ng OSE waits for the a server before switching to the next failover server is set in the time-reopen() option.
If failback() is not set, syslog-ng OSE does not attempt to return to the primary server even if it becomes available. In case the failover server fails, syslog-ng OSE attempts to connect the next failover server in the list in round-robin fashion.
|
|
Caution:
The failover servers must be accessible on the same port as the primary server. | |
| failback() |
|
Description: Available only in syslog-ng Open Source Edition version 3.17 and later.
When syslog-ng OSE starts up, it always connects to the primary server first. In the failover() option there is a possibility to customize the failover modes.
Depending on how you set the failback() option, syslog-ng OSE behaves as follows:
-
round-robin mode: If failback() is not set, syslog-ng OSE does not attempt to return to the primary server even if it becomes available. In case the failover server fails, syslog-ng OSE attempts to connect the next failover server in the list in round-robin fashion.
Example: round-robin mode
In the following example syslog-ng OSE handles the logservers in round-robin fashion if the primary logserver becomes inaccessible (therefore failback() option is not set). destination d_network {
network(
"primary-server.com"
port(601)
failover( servers("failover-server1", "failover-server2") )
);
};
-
failback mode: If failback() is set, syslog-ng OSE attempts to return to the primary server.
After syslog-ng OSE connects a secondary server during a failover, it sends a probe every tcp-probe-interval() seconds towards the primary server. If the primary logserver responds with a TCP ACK packet, the probe is successful. When the number of successful probes reaches the value set in the successful-probes-required() option, syslog-ng OSE tries to connect the primary server using the last probe.
|
|
NOTE:syslog-ng OSE always waits for the result of the last probe before sending the next message. So if one connection attempt takes longer than the configured interval, that is, it waits for connection time out, you may experience longer intervals between actual probes. |
Example: failback mode
In the following example syslog-ng OSE attempts to return to the primary logserver, as set in the failback() option: it will check if the server is accessible every tcp-probe-interval() seconds, and reconnect to the primary logserver after three successful connection attempts. destination d_network_2 {
network(
"primary-server.com"
port(601)
failover(
servers("failover-server1", "failover-server2")
failback(
successful-probes-required()
tcp-probe-interval()
)
)
);
};
Default value for tcp-probe-interval(): 60 seconds
Default value for successful-probes-required(): 3 |
NOTE: This option is not available for the connection-less UDP protocol, because in this case the client does not detect that the destination becomes inaccessible.
flags()
| Type: |
no-multi-line, syslog-protocol |
| Default: |
empty set |
Description: Flags influence the behavior of the destination driver.
-
no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line.
-
syslog-protocol: The syslog-protocol flag instructs the driver to format the messages according to the new IETF syslog protocol standard (RFC5424), but without the frame header. If this flag is enabled, macros used for the message have effect only for the text of the message, the message header is formatted to the new standard. Note that this flag is not needed for the syslog driver, and that the syslog driver automatically adds the frame header to the messages.
flush-lines()
| Type: |
number |
| Default: |
Use global setting (exception: for http() destination, the default is 1). |
Description: Specifies how many lines are flushed to a destination at a time. The syslog-ng OSE application waits for this number of lines to accumulate and sends them off in a single batch. Increasing this number increases throughput as more messages are sent in a single batch, but also increases message latency.
The syslog-ng OSE application flushes the messages if it has sent flush-lines() number of messages, or the queue became empty. If you stop or reload syslog-ng OSE or in case of network sources, the connection with the client is closed, syslog-ng OSE automatically sends the unsent messages to the destination.
For optimal performance when sending messages to an syslog-ng OSE server, make sure that the value of flush-lines() is smaller than the window size set in the log-iw-size() option in the source of your server.
frac-digits()
Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received.
NOTE: The syslog-ng OSE application can add the fractions to non-ISO8601 timestamps as well.
NOTE: As syslog-ng OSE is precise up to the microsecond, when the frac-digits() option is set to a value higher than 6, syslog-ng OSE will truncate the fraction seconds in the timestamps after 6 digits.
hook-commands()
Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.
NOTE: The syslog-ng OSE application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable syslog-ng OSE to execute external applications.
Using the hook-commands() when syslog-ng OSE starts or stops
To execute an external program when syslog-ng OSE starts or stops, use the following options:
| startup() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the external program that is executed as syslog-ng OSE starts. |
| shutdown() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the external program that is executed as syslog-ng OSE stops. |
Using the hook-commands() when syslog-ng OSE reloads
To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:
| setup() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines an external program that is executed when the syslog-ng OSE configuration is initiated, for example, on startup or during a syslog-ng OSE reload. |
| teardown() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines an external program that is executed when the syslog-ng OSE configuration is stopped or torn down, for example, on shutdown or during a syslog-ng OSE reload. |
Example: Using the hook-commands() with a network source
In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as syslog-ng OSE is started/stopped.
The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the syslog-ng OSE created rule is there, packets can flow, otherwise the port is closed.
source {
network(transport(udp)
hook-commands(
startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
shutdown("iptables -D LOGCHAIN 1")
)
);
};
ip-protocol()
Description: Determines the internet protocol version of the given driver (network() or syslog()). The possible values are 4 and 6, corresponding to IPv4 and IPv6. The default value is ip-protocol(4).
Note that listening on a port using IPv6 automatically means that you are also listening on that port using IPv4. That is, if you want to have receive messages on an IP-address/port pair using both IPv4 and IPv6, create a source that uses the ip-protocol(6). You cannot have two sources with the same IP-address/port pair, but with different ip-protocol() settings (it causes an Address already in use error).
For example, the following source receives messages on TCP, using the network() driver, on every available interface of the host on both IPv4 and IPv6.
source s_network_tcp { network( transport("tcp") ip("::") ip-protocol(6) port(601) ); };
ip-tos()
Description: Specifies the Type-of-Service value of outgoing packets.
ip-ttl()
Description: Specifies the Time-To-Live value of outgoing packets.
keep-alive()
| Type: |
yes or no |
| Default: |
yes |
Description: Specifies whether connections to destinations should be closed when syslog-ng is reloaded. Note that this applies to the client (destination) side of the syslog-ng connections, server-side (source) connections are always reopened after receiving a HUP signal unless the keep-alive option is enabled for the source.
localip()
| Type: |
string |
| Default: |
0.0.0.0 |
Description: The IP address to bind to before connecting to target.
localport()
Description: The port number to bind to. Messages are sent from this port.
log-fifo-size()
| Type: |
number |
| Default: |
Use global setting. |
Description: The number of messages that the output queue can store.
mark-freq()
| Accepted values: |
number [seconds] |
| Default: |
1200 |
Description: An alias for the obsolete mark() option, retained for compatibility with syslog-ng version 1.6.x.
The number of seconds between two MARK messages. MARK messages are generated when there was no message traffic to inform the receiver that the connection is still alive. If set to zero (0), no MARK messages are sent. The mark-freq() can be set for global option and/or every MARK capable destination driver if mark-mode() is periodical or dst-idle or host-idle. If mark-freq() is not defined in the destination, then the mark-freq() will be inherited from the global options. If the destination uses internal mark-mode(), then the global mark-freq() will be valid (does not matter what mark-freq() set in the destination side).
mark-mode()
| Accepted values: |
internal | dst-idle | host-idle | periodical | none | global |
| Default: |
internal for pipe, program drivers
none for file, unix-dgram, unix-stream drivers
global for syslog, tcp, udp destinations
host-idle for global option |
Description: The mark-mode() option can be set for the following destination drivers: file(), program(), unix-dgram(), unix-stream(), network(), pipe(), syslog() and in global option.
-
internal: When internal mark mode is selected, internal source should be placed in the log path as this mode does not generate mark by itself at the destination. This mode only yields the mark messages from internal source. This is the mode as syslog-ng OSE 3.3 worked. MARK will be generated by internal source if there was NO traffic on local sources:
file(), pipe(), unix-stream(), unix-dgram(), program()
-
dst-idle: Sends MARK signal if there was NO traffic on destination drivers. MARK signal from internal source will be dropped.
MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
-
host-idle: Sends MARK signal if there was NO local message on destination drivers. for example, MARK is generated even if messages were received from tcp. MARK signal from internal source will be dropped.
MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
-
periodical: Sends MARK signal perodically, regardless of traffic on destination driver. MARK signal from internal source will be dropped.
MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().
-
none: Destination driver drops all MARK messages. If an explicit mark-mode() is not given to the drivers where none is the default value, then none will be used.
-
global: Destination driver uses the global mark-mode() setting. Note that setting the global mark-mode() to global causes a syntax error in syslog-ng OSE.
NOTE: In case of dst-idle, host-idle and periodical, the MARK message will not be written in the destination, if it is not open yet.
Available in syslog-ng OSE 3.4 and later.
port() or destport()
| Type: |
number |
| Default: |
601 |
Description: The port number to connect to. Note that the default port numbers used by syslog-ng do not comply with the latest RFC which was published after the release of syslog-ng 3.0.2, therefore the default port numbers will change in the future releases.
so-broadcast()
| Type: |
yes or no |
| Default: |
no |
Description: This option controls the SO_BROADCAST socket option required to make syslog-ng send messages to a broadcast address. For details, see the socket(7) manual page.
so-keepalive()
| Type: |
yes or no |
| Default: |
no |
Description: Enables keep-alive messages, keeping the socket open. This only effects TCP and UNIX-stream sockets. For details, see the socket(7) manual page.
so-rcvbuf()
Description: Specifies the size of the socket receive buffer in bytes. For details, see the socket(7) manual page.
so-sndbuf()
Description: Specifies the size of the socket send buffer in bytes. For details, see the socket(7) manual page.
spoof-source()
| Type: |
yes or no |
| Default: |
no |
Description: Enables source address spoofing. This means that the host running syslog-ng generates UDP packets with the source IP address matching the original sender of the message. It is useful when you want to perform some kind of preprocessing using syslog-ng then forward messages to your central log management solution with the source address of the original sender. This option only works for UDP destinations though the original message can be received by TCP as well. This option is only available if syslog-ng was compiled using the --enable-spoof-source configuration option.
The maximum size of spoofed datagrams in udp() destinations is set to 1024 bytes by default. To change the maximum size, use the spoof-source-max-msglen() option.
NOTE: Anything above the size of the maximum transmission unit (MTU), which is 1500 bytes by default, is not recommended because of fragmentation.
The maximum datagram in IP protocols (both IPv4 and IPv6) is 65535 bytes including the IP and UDP headers. The minimum size of the IPv4 header is 20 bytes, the IPv6 is 40 bytes, and the UDP is 8 bytes.
suppress()
| Type: |
seconds |
| Default: |
0 (disabled) |
Description: If several identical log messages would be sent to the destination without any other messages between the identical messages (for example, an application repeated an error message ten times), syslog-ng can suppress the repeated messages and send the message only once, followed by the Last message repeated n times. message. The parameter of this option specifies the number of seconds syslog-ng waits for identical messages.
tcp-keepalive-intvl()
| Type: |
number [seconds] |
| Default: |
0 |
Description: Specifies the interval (number of seconds) between subsequential keepalive probes, regardless of the traffic exchanged in the connection. This option is equivalent to /proc/sys/net/ipv4/tcp_keepalive_intvl. The default value is 0, which means using the kernel default.
|
|
Caution:
The tcp-keepalive-time(), tcp-keepalive-probes(), and tcp-keepalive-intvl() options only work on platforms which support the TCP_KEEPCNT, TCP_KEEPIDLE,and TCP_KEEPINTVL setsockopts. Currently, this is Linux.
A connection that has no traffic is closed after tcp-keepalive-time() + tcp-keepalive-intvl() * tcp-keepalive-probes() seconds. |
Available in syslog-ng OSE version 3.4 and later.
tcp-keepalive-probes()
Description: Specifies the number of unacknowledged probes to send before considering the connection dead. This option is equivalent to /proc/sys/net/ipv4/tcp_keepalive_probes. The default value is 0, which means using the kernel default.
|
|
Caution:
The tcp-keepalive-time(), tcp-keepalive-probes(), and tcp-keepalive-intvl() options only work on platforms which support the TCP_KEEPCNT, TCP_KEEPIDLE,and TCP_KEEPINTVL setsockopts. Currently, this is Linux.
A connection that has no traffic is closed after tcp-keepalive-time() + tcp-keepalive-intvl() * tcp-keepalive-probes() seconds. |
Available in syslog-ng OSE version 3.4 and later.
tcp-keepalive-time()
| Type: |
number [seconds] |
| Default: |
0 |
Description: Specifies the interval (in seconds) between the last data packet sent and the first keepalive probe. This option is equivalent to /proc/sys/net/ipv4/tcp_keepalive_time. The default value is 0, which means using the kernel default.
|
|
Caution:
The tcp-keepalive-time(), tcp-keepalive-probes(), and tcp-keepalive-intvl() options only work on platforms which support the TCP_KEEPCNT, TCP_KEEPIDLE,and TCP_KEEPINTVL setsockopts. Currently, this is Linux.
A connection that has no traffic is closed after tcp-keepalive-time() + tcp-keepalive-intvl() * tcp-keepalive-probes() seconds. |
Available in syslog-ng OSE version 3.4 and later.
template()
| Type: |
string |
| Default: |
A format conforming to the default logfile format. |
Description: Specifies a template defining the logformat to be used in the destination. Macros are described in Macros of syslog-ng OSE. Please note that for network destinations it might not be appropriate to change the template as it changes the on-wire format of the syslog protocol which might not be tolerated by stock syslog receivers (like syslogd or syslog-ng itself). For network destinations make sure the receiver can cope with the custom format defined.
NOTE: If a message uses the IETF-syslog format (RFC5424), only the text of the message can be customized (that is, the $MESSAGE part of the log), the structure of the header is fixed.
template-escape()
| Type: |
yes or no |
| Default: |
no |
Description: Turns on escaping for the ', ", and backspace characters in templated output files. This is useful for generating SQL statements and quoting string contents so that parts of the log message are not interpreted as commands to the SQL server.
throttle()
Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using disk-buffer as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.
time-zone()
| Type: |
name of the timezone, or the timezone offset |
| Default: |
unspecified |
Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see Date-related macros.
The timezone can be specified by using the name, for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format, for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.
tls()
| Type: |
tls options |
| Default: |
n/a |
Description: This option sets various options related to TLS encryption, for example, key/certificate files and trusted CA locations. TLS can be used only with tcp-based transport protocols. For details, see TLS options.
transport()
| Type: |
udp, tcp, or tls |
| Default: |
tcp |
Description: Specifies the protocol used to send messages to the destination server.
If you use the udp transport, syslog-ng OSE automatically sends multicast packets if a multicast destination address is specified. The tcp transport does not support multicasting.
ts-format()
| Type: |
rfc3164, bsd, rfc3339, iso |
| Default: |
rfc3164 |
Description: Override the global timestamp format (set in the global ts-format() parameter) for the specific destination. For details, see ts-format().
NOTE: This option applies only to file and file-like destinations. Destinations that use specific protocols (for example, network(), or syslog()) ignore this option. For protocol-like destinations, use a template locally in the destination, or use the proto-template option.
