After more than a year, the latest version of syslog-ng compiles again on Red Hat Enterprise Linux version 6. This is thanks to a patch from Balázs Scheidler which resolves compatibility problems with older glib releases by implementing the missing functions within syslog-ng. As someone living on the edge I consider RHEL 6 ancient (even sometimes RHEL 7), but this release is still in wide use. This is the last RHEL release without systemd and also forms the base of Amazon’s Linux AMI running millions of instances. RHEL 6 is supported by Red Hat almost until the end of 2020.
By the time of this writing the latest version of syslog-ng is 3.13.2. Some bugs were found only after release, fixes for those were added to the 3.13 stable branch on github: https://github.com/balabit/syslog-ng/tree/3.13/master Instead of the official release tgz I used this git branch, added the compatibility patch on top of this and generated a new release tgz from these sources. Along the way I also added the necessary dependencies to the source rpm to enable GeoIP2 support.
My unofficial 3.13 packages are available at https://copr.fedorainfracloud.org/coprs/czanik/syslog-ng313epel6/ While it is possible to download files using a browser (I met quite a few people doing so), I would rather recommend using a package manager. The following steps help you to configure the package manager and install syslog-ng:
rpm -Uvh epel-release-latest-6.noarch.rpm
yum install syslog-ng
Add any further sub-packages you need, for example geoip if you want to figure out geo-location from IP addresses.
yum erase rsyslog