Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

This is Logsurfer - the real-time log monitoring and alerting tool.

Many enhancing features have been added to this version of Logsurfer,
refer to the ChangeLog file in this release for details.

Refer to Logsurfer page at:

General Comments:

To provide one simple and generic interface to regular expressions it
was necessary to use a portable regex-library. Logsurfer uses the GNU
regex library (version 0.12). To simplify installation and to use one
"configure" command for the complete package the regex.[ch] files were
integrated in the logsurfer source directory. For more information
read the README file in the regex directory.

The software was compiled and tested using the GNU-C-Compiler, but
others should work without any problems.

Logsurfer is often used to process / analyze system logs, which is a
good idea (and is, incidentally, one of the design goals). For this
purpose it is not necessary to run the software with "root"
privileges. When using the software it is important to remember that,
depending on the sites logsurfer configuration, external programs may
be started and react to input derived from the processed log files. As
the log files can be influenced by remote users (the very nature of the
logging process causes events to be recorded which may be external to
the computer concerned) the system admin should keep in mind that some
specific configurations may, therefore, represent a higher than
acceptable level of risk since, while logsurfer itself was written
with security in mind, programs started via the configuration most
probably were not. Programs should only be started when absolutely
necessary and only then, when the associated risks have been
considered.  The only privileges needed to be granted to logsurfer are
those necessary to read the input file. If the log files are not world
readable, it is probably best to create a new group and make the log
files readable by that group.  Logsurfer can then be started with a
userid, that is a member of the group.

In order to reduce the risks associated with the above mentioned
problems, logsurfer prints a warning message if started as root. If
you really know what your doing, this behavior can be suppressed by
removing the "-DWARN_ROOT" flag from the "CPPFLAGS" definition in the

There is one really ugly hack for sendmail included in the code. If
sendmail is used to post a message or report to one or more e-mail
addresses, problems may occur when an unusual amount of activity
causes a many instances of sendmail. This may result in memory
exhaustion and inordinately long message delivery times. It is
therefore strongly recommended to invoke sendmail in "queue-only"
mode, which takes the messages and places them in the queue directory
for later delivery: see "sendmail -odq". This configuration results in
a relatively short runtime for the sendmail process and a cure for the
multiple sendmail instance problem.  The drawback is, of course, that 
important mail-messages may be delayed until the mail queue is flushed
(see "sendmail -q<value>", where value is the time between queue
flushes). If logsurfer is compiled with the define SENDMAIL_FLUSH
(i.e. -DSENDMAIL_FLUSH in the CFLAGS definition in the src/Makefile),
logsurfer will flush the mail queue if:
- external programs were executed
- no execution of external programs has occurred for 30 seconds (this
  is effected by executing "/usr/lib/sendmail -q" - see src/exec.c)


Compilation should be very easy:
  % ./configure

If the location for the "logsurfer.conf" file is to be changed from
its default in /usr/local/etc then use the --with-etcdir parameter to
configure, e.g.:
  % ./configure --with-etcdir=/your/etc/dir

"Makefile" and "config.h" should be checked and, if need be, tweaked
manually, before the compile. The compilation can be effected with:
  % make

This should build one program called "logsurfer", which, with its
associated man pages, can be copied to its final destination with:
  % make install


This is the difficult part...
The configuration file syntax and some hints can be found in the
manpage for "logsurfer.conf".  It is strongly suggested, that
logsurfer be configured progressively, i.e. starting with a small
configuration which functions and adding (or changing) rules
progressively, testing after each step, until the goal is reached.
One possible approach is to define rules to ignore log file messages,
which have known causes and consequences, and add a last rule
(i.e. the system default) which causes all other log messages to be
mailed to the person (or persons) responsible. such a default rule may
look something like:
    ".*" - - - 0 pipe "/usr/lib/sendmail -odq logsurfer"

This rule sends the message line to the email-address "logsurfer"
(which is probably an alias pointing to the maintainer) if none of the
other rules above it match. The maintainer can then decide on the
correct reaction to the message, which may simply to add another
ignore rule to the configuration file for the message (class).

Any changes to the configuration file will only take effect AFTER
logsurfer has been stopped and restarted. More information can be
found in the man pages.

A number of configuration examples can also be found at


A number of small support programs can be found in the "contrib"
directory, which may be useful with logsurfer.


The package has only been thoroughly tested in the Solaris 2.5
environment. It has been successfully compiled on a number of other
systems, but has not been tested in great depth. Should problems
occur, please inform the DFN-CERT.


Thanks to
- The authors of logsurfer (Wolfgang Ley and Uwe Ellerman) for
  designing and implementing the software
- Klaus-Peter Kossakowski and Stefan Kelm (all DFN-CERT) for their help
  during development and planning
- Wietse Venema ( for the template of the
  disclaimer file
- The various authors of the regular expression library.
- Jan Krueger ( for finding the most
  serious bug ("-f" not working on all systems) and some other
  suggestions like pidfile or non-ansi prototypes
- Assar ( for the special information on AIX and for
  hints on building the package in a separate directory from the source.
- Niko Makila ( for the ---with-etcdir improvement of
  the configure script
- David Kibilka ( for testing the context
  linelimit patch
- Gregor Kopf of Recurity Labs GmbH and Jan Kohlrausch of DFN-CERT for
  highlighting a double free() bug
- Mike Santos for patches to implement -D and -F


Please let us know if and what kind of problems occur when using the
logsurfer package. It will help us fix the problems and help others
avoid replicating them. Please send all bug reports and feedback to:


Monitoring system logs in real-time






No releases published


No packages published