rsyslog vs. syslog-ng

Written by Rainer Gerhards (2008-01-29)

We have often been asked abut a comparison sheet between rsyslog and syslog-ng. Unfortunately, I do not know much about syslog-ng, I did not even use it once. Also, there seems to be no comprehensive feature sheet available for syslog-ng. So I started this comparison, but it probably is not complete. For sure, I miss some syslog-ng features. This is not an attempt to let rsyslog shine more than it should. I just used the rsyslog feature sheet as a staring point, simply because it was available. If you would like to add anything to the chart, or correct it, please simply drop me a line. I would love to see a real honest and up-to-date comparison sheet, so please don't be shy ;)

Feature rsyslog syslog-ng
native support for writing to MySQL databases yes paid edition only
native support for writing to Postgres databases yes paid edition only
support for (plain) tcp based syslog yes yes
support for sending and receiving compressed syslog messages yes I think "no"
support for on-demand on-disk spooling of messages yes paid edition only
ability to configure backup syslog/database servers yes no
support for receiving messages via reliable RFC 3195 delivery yes no
ability to generate file names and directories (log targets) dynamically yes yes
control of log output format, including ability to present channel and priority as visible log data yes not sure...
good timestamp format control; at a minimum, ISO 8601/RFC 3339 second-resolution UTC zone yes ? (I guess so)
ability to reformat message contents and work with substrings yes I think yes
support for log files larger than 2gb yes yes
support for file size limitation and automatic rollover command execution yes yes (?)
support for running multiple rsyslogd instances on a single machine yes ? (but I think yes)
support for ssl-protected syslog via stunnel via stunnel
paid edition natively
ability to filter on any part of the message, not just facility and severity yes yes
ability to use regular expressions in filters yes yes
support for discarding messages based on filters yes ?
ability to execute shell scripts on received messages yes yes
ability to pipe messages to a continously running program no yes
ability to preserve the original hostname in NAT environments and relay chains yes yes (think so)
ability to limit the allowed network senders (syslog ACLs) yes yes (?)
powerful BSD-style hostname and program name blocks for easy multi-host support yes no
massively multi-threaded for tomorrow's multi-core machines yes ?
support for IETF's new syslog-protocol draft yes no
support for syslog-transport-tls based framing on syslog/tcp connections yes no (?)
support for IPv6 yes yes (?)
ability to control repeated line reduction ("last message repeated n times") on a per selector-line basis yes yes (?)
config file includes, also full directory includes yes ?
supports multiple actions per selector/filter condition yes ?
plug-in interface yes no (?)
Windows Event Log gatherer via EventReporter or MonitorWare Agent (both commercial software) via Windows agent, paid edition only
config file format compatible to legacy syslogd but ugly clean but not backwards compatible
support for GSS-API yes ?
web interface phpLogCon
[also works with php-syslog-ng]
php-syslog-ng
? (probably many I do no know off...) no yes

This document is current as of 2008-01-29 and definitely incomplete (I did not yet manage to complete it!).