Batched Compression (om_batchcompress)
This module uses a custom protocol to send batches of log messages to a remote NXLog instance configured with the im_batchcompress module. The messages are compressed in batches to achieve better compression ratios than would be possible individually. The module serializes and sends all fields across the network so that structured data is preserved. It can be configured to send data using SSL for secure and encrypted data transfer. The protocol contains an acknowledgment to ensure that the data is received by the remote server. The batch will be resent if the server does not respond with an acknowledgment.
Configuration
The om_batchcompress module accepts the following directives in addition to the common module directives. The Host directive is required.
Required directives
The following directives are required for the module to start.
The module connects to this IP address or hostname. If additional hosts are specified on new lines, the module works in a failover configuration. If a destination becomes unavailable, the module automatically fails over to the next one. If the last destination becomes unavailable, the module fails over to the first destination. The port number can be defined by appending it to the hostname or IP address using a colon as a separator ( IPv6 addresses must be enclosed in square brackets (
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TLS/SSL directives
The following directives configure secure data transfer via TLS/SSL.
Specifies if the connection should be allowed with an expired certificate.
If set to |
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Specifies if the certificate FQDN should be validated against the server hostname or not.
If set to |
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Specifies if the connection should be allowed regardless of the certificate verification results.
If set to |
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Path to a directory containing certificate authority (CA) certificates. These certificates will be used to verify the certificate presented by the remote host. The certificate files must be named using the OpenSSL hashed format, i.e. the hash of the certificate followed by .0, .1 etc. To find the hash of a certificate using OpenSSL:
For example, if the certificate hash is A remote host’s self-signed certificate (which is not signed by a CA) can also be trusted by including a copy of the certificate in this directory. |
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Path of the certificate authority (CA) certificate that will be used to verify the certificate presented by the remote host. A remote host’s self-signed certificate (which is not signed by a CA) can be trusted by specifying the remote host certificate itself. In the case of certificates signed by an intermediate CA, the certificate specified must contain the complete certificate chain (certificate bundle). |
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This optional directive, supported only on Windows, defines a pattern for locating a suitable CA (Certificate Authority) certificate and its thumbprint in the native Windows Certificate Storage.
The pattern must follow PCRE2 rules and use the format Configuration examples:
or
A normal log output example would look like as follows:
This directive is only supported on Windows. |
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This optional directive, supported only on Windows, specifies the thumbprint of the certificate authority (CA) certificate that will be used to verify the certificate presented by the remote host. The hexadecimal fingerprint string can be copied from Windows Certificate Manager (certmgr.msc). Whitespaces are automatically removed. The certificate must be added to a Windows certificate store that is accessible by NXLog. This directive is mutually exclusive with the CADir, CAFile and CAPattern directives. |
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Path of the certificate file that will be presented to the remote host during the SSL handshake. |
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Path of the private key file that was used to generate the certificate specified by the CertFile directive. This is used for the SSL handshake. |
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This optional directive, supported only on Windows, defines a pattern for identifying a corresponding certificate and its thumbprint within the native Windows Certificate Storage.
The pattern must follow PCRE2 rules and use the format Configuration examples:
or
A normal log output example would look like as follows:
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This optional directive, supported only on Windows, specifies the thumbprint of the certificate that will be presented to the remote server during the HTTPS handshake.
The hexadecimal fingerprint string can be copied from Windows Certificate Manager (certmgr.msc).
Whitespaces are automatically removed.
The certificate must be imported to the
When the global directive UseCNGCertificates is set to
On the contrary, when the global directive UseCNGCertificates is set to The usage of the directive is the same in all cases:
This directive is only supported on Windows and is mutually exclusive with the CertFile and CertKeyFile directives. |
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Path to a directory containing certificate revocation list (CRL) files. These CRL files will be used to check for certificates that were revoked and should no longer be accepted. The files must be named using the OpenSSL hashed format, i.e. the hash of the issuer followed by .r0, .r1 etc. To find the hash of the issuer of a CRL file using OpenSSL:
For example if the hash is |
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Path of the certificate revocation list (CRL) which will be used to check for certificates that have been revoked and should no longer be accepted. Example to generate a CRL file using OpenSSL:
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This optional directive specifies a file with dh-parameters for Diffie-Hellman key exchange. These parameters can be generated with dhparam(1ssl). If this directive is not specified, default parameters will be used. See the OpenSSL Wiki for further details. |
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Passphrase of the private key specified by the CertKeyFile directive. A passphrase is required when the private key is encrypted. The following example generates a private key with Triple DES encryption using OpenSSL:
This directive is not required for passwordless private keys. |
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If set to This directive is only supported on Windows. |
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Specifies if the remote host must present a certificate.
If set to |
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This optional directive, supported only on Windows, if set to |
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The signature algorithm parameter that is being sent to the Windows SSL library. Allowed values depend on the available encryption providers. This directive is only supported on Windows. |
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This optional directive specifies the hostname used for Server Name Indication (SNI). If not specified, it defaults to the hostname in the Host directive. |
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This optional directive can be used to set the permitted cipher list for TLSv1.2 and below, overriding the default.
Use the format described in the ciphers(1ssl) man page.
For example specify
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This optional directive can be used to set the permitted cipher list for TLSv1.3. Use the same format as in the SSLCipher directive. Refer to the OpenSSL documentation for a list of valid TLS v1.3 cipher suites. The default value is:
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Specifies if data compression is enabled when sending data over the network.
The compression mechanism is based on the zlib compression library.
The default value is
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This directive can be used to set the allowed SSL/TLS protocol(s). It takes a comma-separated list of values which can be any of the following: |
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If set to TRUE, the module uses the Windows Cryptography API: Next Generation (CNG) to access the private keys associated with certificates identified by a thumbprint. This directive is only supported on Windows. |
Optional directives
This optional directive specifies the local port number of the connection. If this is not specified, a random high port number will be used, which is not always ideal in firewalled network environments.
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This optional directive sets the reconnect interval in seconds. If it is set, the module attempts to reconnect in every defined second. If it is not set, the reconnect interval will start at 1 second and double with every attempt. If the duration of the successful connection is greater than the current reconnect interval, then the reconnect interval will be reset to 1 sec.
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This optional directive defines the behavior when the connection with the remote host is lost.
When set to |
Procedures
The following procedures are exported by om_batchcompress.
reconnect();
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Force a reconnection. This can be used from a Schedule block to periodically reconnect to the server.
The reconnect() procedure must be used with caution. If configured, it can attempt to reconnect after every event sent, potentially overloading the destination system.
Examples
This configuration forwards logs in compressed batches to a remote NXLog agent over the default port. Batches are sent at least once every two seconds, or more frequently if the buffer reaches 100 events.
<Input null>
Module im_null
BatchSize 200
BatchFlushInterval 2
</Input>
<Output batchcompress>
Module om_batchcompress
Host example.com:2514
</Output>
<Route null_to_batchcompress>
Path null => batchcompress
</Route>
This configuration sends logs in compressed batches to a remote NXLog instance in a failover configuration (multiple Hosts defined).
<Output batchcompress>
Module om_batchcompress
# destination host / IP and destination port
Host example1:2514
# first fail-over
Host example2:2514
</Output>