1. CIS 193A – Lesson3 Vigilance! Logging & Monitoring Syslog Logrotate Logwatch Accounting

2. CIS 193A – Lesson3 Focus Question What tools does Linux provide for organizing and making useful sense of logged output?

3. CIS 193A – Lesson3 The Syslog Utility Daemons: syslogd and klogd Configuration: /etc/syslog.conf Log files: /var/log/messages secure maillog cron spooler boot.log

4. CIS 193A – Lesson3 Syslog Facilities Syslog categorizes messages into the following “facilities”: –authpriv- local0 –cron - local1 –daemon - local2 –ftp - local3 –kern - local4 –lpr- local5 –mail - local6 –news - local7 –syslog,user,uucp

5. CIS 193A – Lesson3 Syslog – Levels of Logging Syslog organizes messages within a facility according to level of importance: –emerg –alert –crit –err –warning –notice –info –debug Logging at one of these levels, logs all messages at that level and above

6. CIS 193A – Lesson3 Log Files Syslog logs to files, but in UNIX, everything is a file! –Regular files in /var/log/ –Terminal screens: /dev/console –Another program: | program –A remote syslog server: @servername

7. CIS 193A – Lesson3 The logger Command The logger command allows shell scripts to use the syslog facility: logger [-t tag] –p facility.level “message” The logger command will also read the message to log from stdin: echo “message” | logger –p facility.level Often used in service init scripts.

8. CIS 193A – Lesson3 The logrotate Facility Customizable, pluggable log-rotating system. Executable: /usr/sbin/logrotate activated by cron on a daily basis Configuration: /etc/logrotate.conf and /etc/logrotate.d/* logrotate.conf contains global settings, and individual services add their settings to logrotate.d

9. CIS 193A – Lesson3 Features of logrotate Rotates any file through a series of predefined extensions:.1,.2, ….n You configure the frequency. May compress files as well. May rotate based on size of file. May mail you the last file of series rather than delete.

10. CIS 193A – Lesson3 Configuration File Syntax Filename [,filename] { rotate n# n is number of copies weekly# frequency: daily, monthly compress mail email size nk postrotate command to restart logging service endscript }

11. CIS 193A – Lesson3 logwatch

12. CIS 193A – Lesson3 The logwatch Service Customizable, pluggable log-monitoring system written in perl. Goes through your logs for a given period of time and make a report in the areas that you wish with the detail that you wish. Executable: /usr/sbin/logwatch Configuration: /etc/logwatch /usr/share/logwatch/default.conf/*

13. CIS 193A – Lesson3 logwatch Features Will analyze logfiles by service. Supports three levels of detail. Analyzes today’s, yesterday’s or historical data. Mails summary of analysis to root account. Extensible, drop-in scripts and configuration files.

14. CIS 193A – Lesson3 Logwatch Examples Although logwatch is normally run from cron just before a logrotate is done, you can run the command from the command line: logwatch --range all –-detail high –-service sshd –-print Logwatch –-range yesterday –-detail low –-logfile secure

15. CIS 193A – Lesson3 Process Accounting

16. CIS 193A – Lesson3 A Suite of Utilities As a service:psacct –logs to /var/account/pacct As a client: lastcomm Other clients: –ac –sa –last, lastb

17. CIS 193A – Lesson3 Review

18. CIS 193A – Lesson3 Focus Question What tools does Linux provide for organizing and making useful sense of logging output? Syslog allows you to organize log messages from different facilities according to their severity level. Logrotate prevents the log files from getting too large, and logwatch summarizes information from the logs.