If the clients run syslog-ng, then use the ISO timestamp, because it includes timezone information. That way you do not need to adjust the recv-time-zone() parameter of syslog-ng.
If you want syslog-ng to output timestamps in Unix (POSIX) time format, use the S_UNIXTIME and R_UNIXTIME macros. You do not need to change any of the timezone related parameters, because the timestamp information of incoming messages is converted to Unix time internally, and Unix time is a timezone-independent time representation. (Actually, Unix time measures the number of seconds elapsed since midnight of Coordinated Universal Time (UTC) January 1, 1970, but does not count leap seconds.)
The following release policy applies to syslog-ng Premium Edition (syslog-ng PE):
The initial release includes new features, bug fixes and security updates. After the initial release, only maintenance releases are published on this path, containing only bug fixes and security updates. The maintenance release frequency is typically four months.
Versioning: the first digit identifies the LTS main version (for example, 6.0.x), the second digit is always a 0, and the third digit designates the maintenance release (for example, 6.0.19). A long term support path is typically supported for three years after its original release.
Rolling releases include new features, bug fixes and security updates. Release frequency on this path is typically two months.
Versioning: the first digit identifies the main version of the rolling release path, the second digit is always a 0, and the third digit designates published on this path. Rolling releases are typically supported for a year.
For further information regarding the syslog-ng PE LTS and Rolling releases, see the syslog-ng Premium Edition Product Life Cycle Table.
Downgrading from a feature release to an earlier (and thus unsupported) feature release, or to the previous LTS release is officially not supported, but usually works as long as your syslog-ng PE configuration file is appropriate for the old syslog-ng PE version. However, persistent data like the position of the last processed message in a file source will be probably lost.
Logstore files created with a newer version of syslog-ng PE might not be readable with an older version of syslog-ng PE.
NOTE: Bug fixes and security updates are always issued in the latest & greatest releases, and never for previous releases. For example, in case of Long Term Support path, if a bug was reported by a customer for 6.0.17 LTS, the fix will be released in version 6.0.18 or in a later maintenance release. The same logic is true to rolling releases, for example, if a bug gets reported for 7.0.20, the fix will be issued in 7.0.21 or a later release.
NOTE: The LTS path for syslog-ng PE will contain support only for the Windows Agent and AIX components after 31-Jul-2020. All other platforms will be deprecated from the LTS path. One Identity advises customers to migrate to version 7.0.x where possible to be eligible for full support going forward.
Buying a syslog-ng Premium Edition (syslog-ng PE) license permits you to perform the following:
Install one instance of the syslog-ng PE application in server mode to a single host. This host acts as the central log server of the network. You have to install the license file only on this host.
Install the syslog-ng PE application in relay or client mode on host computers within your organization (on any supported platform). You cannot redistribute the application to third parties. The total number of hosts permitted to run syslog-ng PE in relay or client mode is limited by the syslog-ng PE license. The client and relay hosts may use any operating system supported by syslog-ng PE. For details, see syslog-ng.com.
The syslog-ng Premium Edition license determines the number of individual hosts (also called log source hosts) that can send log messages to syslog-ng PE.
License grants and legal restrictions are fully described in the Software Transaction, License and End User License Agreements. Note that the Software Transaction, License and End User License Agreements and the Product Guide apply only to scenarios where the Licensee (the organization who has purchased the product) is the end user of the product. In any other scenario — for example, if you want to offer services provided by syslog-ng Premium Edition to your customers in an OEM or a Managed Service Provider (MSP) scenario — you have to negotiate the exact terms and conditions with One Identity.