On the Microsoft Azure Sentinel user interface, you can filter log events by referring to log-type parameters. Although the log-type parameters query information with their custom query language (namely, Kusto), they are essentially table fields in a database.
For more information about log-type parameters, see Microsoft Azure: Write data to Log Analytics repository.
For more information about the Kusto query language, see Microsoft Azure: Query Language: Overview.
The log-type parameter is mandatory for the Microsoft Azure Sentinel HTTP Data Collector API interface, and for syslog-ng Premium Edition (syslog-ng PE), its default value is Syslog_CL.
NOTE: While Microsoft Azure Sentinel accepts log events from external sources, it also has built-in log types. To differentiate external and built-in log types, Azure Sentinel automatically applies the Custom Log-type (_CL) suffix to log events that originate from external sources. Although the log-type parameter is optional (unlike workspace-id and auth-secret, which are mandatory), keep in mind that Microsoft Azure Sentinel will automatically attach the _CL suffix to all log events originating from external sources. For example, log events that originate from syslog-ng PE will be named Syslog_CL by default.
NOTE: If you want to store messages in different log types that all connect to the same workspace-id, you can create multiple sentinel() destinations that have a common workspace-id, but different log-type parameters.
Example syslog-ng PE message
When forwarding messages to Microsoft Azure Sentinel, syslog-ng PE automatically populates the following fields:
{
"SyslogMessage": "<34>Oct 11 22:14:15 sentineluser prog1: message_begin 2020-02-10 08:29:02:329951-default message_end\n",
"SeverityLevel": "notice",
"ProcessID": "",
"HostName": "myhost",
"HostIP": "127.0.0.1",
"Facility": "user",
"EventTime": "2020-02-10T09:29:48+01:00",
"Computer": "ubuntu"
}
The sentinel() destination of syslog-ng Premium Edition (syslog-ng PE) can directly post log messages to Microsoft Azure Sentinel using its HTTP Data Collector API. The sentinel() destination has the following options.
auth-secret()
| Type: |
Provided by Microsoft: Base64-encoded secret, identifying your application. On the syslog-ng PE side, it is handled as string. |
| Default: |
N/A |
batch-bytes()
| Accepted values: |
number [bytes] |
| Default: |
none |
Description: Sets the maximum size of payload in a batch. If the size of the messages reaches this value, syslog-ng PE sends the batch to the destination even if the number of messages is less than the value of the batch-lines() option.
Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng PE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-bytes().
Available in syslog-ng PE version 7.0.12 and later.
batch-lines()
| Type: |
number [lines] |
| Default: |
1 |
Description: Specifies how many lines are flushed to a destination in one batch. The syslog-ng PE 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.
For example, if you set batch-lines() to 100, syslog-ng PE waits for 100 messages.
If the batch-timeout() option is disabled, the syslog-ng PE application flushes the messages if it has sent batch-lines() number of messages, or the queue became empty. If you stop or reload syslog-ng PE or in case of network sources, the connection with the client is closed, syslog-ng PE automatically sends the unsent messages to the destination.
If the batch-timeout() option is enabled and the queue becomes empty, syslog-ng PE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-lines().
For optimal performance, make sure that the syslog-ng PE source that feeds messages to this destination is configured properly: the value of the log-iw-size() option of the source must be higher than the batch-lines()*workers() of the destination. Otherwise, the size of the batches cannot reach the batch-lines() limit.
batch-timeout()
| Type: |
time [milliseconds] |
| Default: |
-1 (disabled) |
Description: Specifies the time syslog-ng PE waits for lines to accumulate in the output buffer. The syslog-ng PE application sends batches to the destinations evenly. The timer starts when the first message arrives to the buffer, so if only few messages arrive, syslog-ng PE sends messages to the destination once every batch-timeout() milliseconds at most.
body()
| Type: |
string or template |
| Default: |
|
Description: The body of the HTTP request, for example, body("${ISODATE} ${MESSAGE}"). You can use strings, macros, and template functions in the body. If not set, it will contain the message received from the source by default.
body-prefix()
| Accepted values: |
string |
| Default: |
none |
Description: The string syslog-ng PE puts at the beginning of the body of the HTTP request, before the log message. Available in syslog-ng PE version 7.0.11 and later.
body-suffix()
| Accepted values: |
string |
| Default: |
none |
Description: The string syslog-ng PE puts to the end of the body of the HTTP request, after the log message. Available in syslog-ng PE version 7.0.11 and later.
ca-dir()
| Accepted values: |
directory name |
| Default: |
none |
Description: 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 PE application uses the CA certificates in this directory to validate the certificate of the peer.
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
ca-file()
| Accepted values: |
Filename |
| Default: |
none |
Description: Name of a file that contains an X.509 CA certificate (or a certificate chain) in PEM format. The syslog-ng PE application uses this certificate to validate the certificate of the HTTPS server. If the file contains a certificate chain, the file must begin with the certificate of the host, followed by the CA certificate that signed the certificate of the host, and any other signing CAs in order.
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
cert-file()
| Accepted values: |
Filename |
| Default: |
none |
Description: Name of a file, that contains an X.509 certificate (or a certificate chain) in PEM format, suitable as a TLS certificate, matching the private key set in the key-file() option. The syslog-ng PE application uses this certificate to authenticate the syslog-ng PE client on the destination server. If the file contains a certificate chain, the file must begin with the certificate of the host, followed by the CA certificate that signed the certificate of the host, and any other signing CAs in order.
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
cipher-suite()
| Accepted values: |
Name of a cipher, or a colon-separated list |
| Default: |
Depends on the OpenSSL version that syslog-ng PE uses |
Description: Specifies the cipher, hash, and key-exchange algorithms used for the encryption, for example, ECDHE-ECDSA-AES256-SHA384. The list of available algorithms depends on the version of OpenSSL used to compile syslog-ng PE. To specify multiple ciphers, separate the cipher names with a colon, and enclose the list between double-quotes, for example:
cipher-suite("ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384")
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
delimiter()
| Accepted values: |
string |
| Default: |
newline character |
Description: By default, syslog-ng PE separates the log messages of the batch with a newline character. You can specify a different delimiter by using the delimiter() option. Available in syslog-ng PE version 7.0.11 and later.
disk-buffer()
Description: This option enables putting outgoing messages into the disk-buffer file of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:
| dir() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the folder where the disk-buffer files are stored.
Note that changing the value the dir() option will not move or copy existing files from the old directory to the new one.
|
|
Caution:
When creating a new dir() option for a disk-buffer file, or modifying an existing one, make sure you delete the persist file.
syslog-ng PE 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 PE will look for or create disk-buffer files in their old location. To ensure that syslog-ng PE 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 file 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 file. 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. |
| quot-size() |
| Type: |
number [messages] |
| Default: |
1000 |
|
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 file already exists, the change will take effect when the disk-buffer file becomes empty. |
| reliable() |
| Type: |
yes|no |
| Default: |
no |
|
Description: If set to yes, syslog-ng PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE 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 option 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 file, the messages stored in the disk-buffer file will be lost. | |
| truncate-size-ratio() |
| Type: |
number (for percentage) between 0 and 1 |
| Default: |
0.1 (10%) |
|
Description: Limits the truncation of the disk-buffer file. Truncating the disk-buffer file can slow down disk I/O operations, but it saves disk space. As a result, syslog-ng PE only truncates the file if the possible disk gain is more than truncate-size-ratio() times disk-buf-size().
|
|
Caution:
One Identity recommends that you do not modify the value of the truncate-size-ratio() option unless you are fully aware of the potential performance implications. | |
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")
)
);
};
headers()
| Type: |
string list |
| Default: |
|
Description: Custom HTTP headers to include in the request, for example, headers("HEADER1: header1", "HEADER2: header2"). If not set, only the default headers are included, but no custom headers.
The following headers are included by default:
-
X-Syslog-Host: <host>
-
X-Syslog-Program: <program>
-
X-Syslog-Facility: <facility>
-
X-Syslog-Level: <loglevel/priority>
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 PE 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 PE to execute external applications.
Using the hook-commands() when syslog-ng PE starts or stops
To execute an external program when syslog-ng PE starts or stops, use the following options:
| startup() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the external program that is executed when syslog-ng PE starts. |
| shutdown() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines the external program that is executed when syslog-ng PE stops. |
Using the hook-commands() when syslog-ng PE reloads
To execute an external program when the syslog-ng PE configuration is initiated or torn down (for example, on startup/shutdown or during a syslog-ng PE reload), use the following options:
| setup() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines an external program that is executed when the syslog-ng PE configuration is initiated, for example, on startup or during a syslog-ng PE reload. |
| teardown() |
| Type: |
string |
| Default: |
N/A |
|
Description: Defines an external program that is executed when the syslog-ng PE configuration is stopped or torn down, for example, on shutdown or during a syslog-ng PE 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 when syslog-ng PE 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 PE 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")
;)
);
};
key-file()
| Accepted values: |
Filename |
| Default: |
none |
Description: Path and name of a file that contains a private key in PEM format, suitable as a TLS key. If properly configured, the syslog-ng PE application uses this private key and the matching certificate (set in the cert-file() option) to authenticate the syslog-ng PE client on the destination server.
The sentinel() destination supports only unencrypted key files (that is, the private key cannot be password-protected).
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
log-fifo-size()
| Type: |
number |
| Default: |
Use global setting. |
Description: The number of messages that the output queue can store.
log-type()
| Type: |
Microsoft Azure Sentinel parameter and an optional syslog-ng PE configuration option |
| Default: |
Syslog_CL for syslog-ng PE |
Description:
On the Microsoft Azure Sentinel user interface, you can filter log events by referring to log-type parameters. Although the log-type parameters query information with their custom query language (namely, Kusto), they are essentially table fields in a database.
The log-type parameter is mandatory for the Microsoft Azure Sentinel HTTP Data Collector API interface, and for syslog-ng Premium Edition, its default value is Syslog_CL.
NOTE: While Microsoft Azure Sentinel accepts log events from external sources, it also has built-in log types. To differentiate external and built-in log types, Azure Sentinel automatically applies the Custom Log-type (_CL) suffix to log events that originate from external sources. Although the log-type parameter is optional (unlike workspace-id and auth-secret, which are mandatory), keep in mind that Microsoft Azure Sentinel will automatically attach the _CL suffix to all log events originating from external sources. For example, log events that originate from syslog-ng PE will be named Syslog_CL by default.
For more information, see Getting the required credentials to configure syslog-ng PE as a Data Connector for Microsoft Azure Sentinel and Log types.
method()
| Type: |
POST | PUT |
| Default: |
POST |
Description: Specifies the HTTP method to use when sending the message to the server.
password()
Description: The password that syslog-ng PE uses to authenticate on the server where it sends the messages.
peer-verify()
| Accepted values: |
yes | no |
| Default: |
yes |
Description: Verification method of the peer. The following table summarizes the possible options and their results depending on the certificate of the peer.
| Local peer-verify() setting |
no (optional-untrusted) |
TLS-encryption |
TLS-encryption |
TLS-encryption |
| yes (required-trusted) |
rejected connection |
rejected connection |
TLS-encryption |
For untrusted certificates only the existence of the certificate is checked, but it does not have to be valid — syslog-ng accepts the certificate even if it is expired, signed by an unknown CA, or its CN and the name of the machine mismatches.
|
|
Caution:
When validating a certificate, the entire certificate chain must be valid, including the CA certificate. If any certificate of the chain is invalid, syslog-ng PE will reject the connection. |
persist-name()
| Type: |
string |
| Default: |
None |
Description:If you receive the following error message during syslog-ng PE startup, set the persist-name() option of the duplicate drivers:
Error checking the uniqueness of the persist names, please override it with persist-name option. Shutting down.
This error occurs if you use identical drivers in multiple sources, for example, if you configure two file sources to read from the same file. In this case, set the persist-name() of the drivers to a custom string, for example, persist-name("example-persist-name1").
proxy()
| Type: |
The proxy server address, in proxy("PROXY_IP:PORT") format.
For example, proxy("http://myproxy:3128") |
| Default: |
None |
Description:
The proxy() option enables you to configure the sentinel driver to use a specific HTTP proxy for all HTTP-based destinations, instead of using the proxy that is configured for the system.
If you do not set the proxy() option, the sentinel driver uses the http_proxy and https_proxy environment variables, as shown in CURLOPT_PROXY explained.
NOTE: Configuring the proxy() option overwrites the default http_proxy and https_proxy environment variables.
retries()
| Type: |
number [of attempts] |
| Default: |
3 |
Description: The number of times syslog-ng PE attempts to send a message to this destination. If syslog-ng PE could not send a message, it will try again until the number of attempts reaches retries(), then drops the message.
To handle HTTP error responses, if the HTTP server returns 5xx codes, syslog-ng PE will attempt to resend messages until the number of attempts reaches retries. If the HTTP server returns 4xx codes, syslog-ng PE will drop the messages.
ssl-version()
| Type: |
string |
| Default: |
None, uses the libcurl default |
Description: Specifies the permitted SSL/TLS version. Possible values: sslv2, sslv3, tlsv1, tlsv1_0, tlsv1_1, tlsv1_2, tlsv1_3.
An alternative way to specify this option is to put it into a tls() block, together with any other TLS options. This allows you to separate these options and ensure better readability.
Make sure that you specify TLS options either using their own dedicated option (ca-dir(), ca-file(), cert-file(), cipher-suite(), key-file(), peer-verify(), and ssl-version()), or using the tls() block and inserting the relevant options within tls(). Avoid mixing the two methods. If you do specify TLS options in both ways, the one that comes later in the configuration file will take effect.
Declaration
destination d_http {
http(
url("http://127.0.0.1:8080")
tls(
ca-dir("dir")
ca-file("ca")
cert-file("cert")
cipher-suite("cipher")
key-file("key")
peer-verify(yes|no)
ssl-version(<the permitted SSL/TLS version>)
)
);
};
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 PE. 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.
throttle()
Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using the disk-buffer option as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.
timeout()
| Type: |
number [seconds] |
| Default: |
0 |
Description: The value (in seconds) to wait for an operation to complete, and attempt to reconnect the server if exceeded. By default, the timeout value is 0, meaning that there is no timeout. Available in version 7.0.4 and later.
url()
| Type: |
URL or list of URLs |
| Default: |
http://localhost/ |
Description: Specifies the hostname or IP address, and optionally the port number of the web service that can receive log data through HTTP. Use a colon (:) after the address to specify the port number of the server. For example: http://127.0.0.1:8000
In case the server on the specified URL returns a redirect request, syslog-ng PE automatically follows maximum 3 redirects. Only HTTP-based and HTTPS-based redirections are supported.
Starting with version 7.0.12, you can specify multiple URLs, for example, url("site1" "site2"). In this case, syslog-ng PE sends log messages to the specified URLs in a load-balance fashion. This means that syslog-ng PE sends each message to only one URL. For example, you can use this to send the messages to a set of ingestion nodes or indexers of your SIEM solution if a single node cannot handle the load. Note that the order of the messages as they arrive on the servers can differ from the order syslog-ng PE has received them, so use load-balancing only if your server can use the timestamp from the messages. If the server uses the timestamp when it receives the messages, the order of the messages will be incorrect.
|
|
Caution:
If you set multiple URLs in the url() option, set the persist-name() option as well to avoid data loss. |
user-agent()
| Type: |
string |
| Default: |
syslog-ng [version]/libcurl[version] |
Description: The value of the USER-AGENT header in the messages sent to the server.
user()
Description: The username that syslog-ng PE uses to authenticate on the server where it sends the messages.
use-system-cert-store()
| Type: |
yes | no |
| Default: |
no |
Description: Use the certificate store of the system for verifying HTTPS certificates. For details, see the curl documentation.
workers()
Description: Specifies the number of worker threads (at least 1) that syslog-ng PE uses to send messages to the server. Increasing the number of worker threads can drastically improve the performance of the destination.
|
|
Caution:
Hazard of data loss!
When you use more than one worker threads together with the disk-buffer option, syslog-ng PE creates a separate disk-buffer file for each worker thread. This means that decreasing the number of workers can result in losing data currently stored in the disk-buffer files. Do not decrease the number of workers when the disk-buffer files are in use. |
If you are using load-balancing (that is, you have configured multiple servers in the url() option), increase the number of worker threads at least to the number of servers. For example, if you have set three URLs (url("site1" "site2" "site3")), set the workers() option to 3 or more.
workspace-id()
| Type: |
Provided by Microsoft: unique hexadecimal number, identifying your Sentinel instance. On the syslog-ng PE side, it is handled as string. |
| Default: |
N/A |
