Syslog is a client/server protocol: the syslog sender sends a small (less than 1KB) textual message to the syslog receiver. The receiver is commonly called "syslogd", "syslog daemon" or "syslog server". Syslog messages can be sent via UDP and/or TCP. The data is sent in cleartext; although not part of the syslog protocol itself, an SSL wrapper can be used to provide for a layer of encryption through SSL/TLS.
Syslog is typically used for computer system management and security auditing. While it has a number of shortcomings, syslog is supported by a wide variety of devices and receivers across multiple platforms. Because of this, syslog can be used to integrate log data from many different types of systems into a central repository.
Syslog is now standardized within the Syslog working group of the IETF.
Until recently, Syslog functioned as a de facto standard, without any authoritative published specification, and many implementations existed (some of which were incompatible with others). In an effort to improve its security, the Internet Engineering Task Force implemented a working group. In 2001, the status quo was documented in RFC 3164. Since then, new additions to syslog have been worked on. A formal specification and standardization of message content and transport layer mechanisms was scheduled for 2005, but is still unfinished.
At different points in time, various companies have attempted patent claims on syslog. This has had little effect on the use and standardization of the protocol.
Regulations, such as SOX, HIPAA and many others are requiring organizations to implement comprehensive security measures, which often include collecting and analyzing logs from many different sources. Syslog has proven to be an effective format to consolidate logs with, as there are many open source and commercial tools for reporting and analysis.
An emerging area of managed security services is the collection and analysis of syslog records for organizations. The MSSPs are able to apply artificial intelligence algorithms to detect patterns and alert customers of problems.