CIS 238Syslog

System logging and monitoring

Syslog• (r)syslog is a utility for tracking and logging all manner of system messages

from the merely informational to the extremely critical. Sysogs stored in

• In LINUX, system logs are stored in /var/log. System messages are recorded in /var/log/messages. Other OS’es may use different files in different directories (e.g. /var/adm).

• Each system message sent to the syslog server has two descriptive labels associated with it that makes the message easier to handle.

- The first describes the function (facility) of the application that generated it. For example, applications such as mail and cron generate messages with easily identifiable facilities named mail and cron. - The second describes the degree of severity of the message.

Syslog

• Severity: Level: Keyword: Description • 0 emergencies System unusable • 1 alerts Immediate action required • 2 critical Critical condition • 3 errors Error conditions • 4 warnings Warning conditions • 5 notifications Normal but significant conditions • 6 informational Informational messages • 7 debugging Debugging messages

Syslog• The files to which syslog writes each type of message received is set in the

/etc/rsyslog.conf configuration file. In older versions of Fedora, this file was named /etc/syslog.conf.

• This file consists of two columns. The first lists the facilities and severities of messages to expect and the second lists the files to which they should be logged. By default, RedHat/Fedora's /etc/rsyslog.conf file is configured to put most of the messages in the file /var/log/messages.

• Example: *.info;mail.none;authpriv.none;cron.none /var/log/messages

• Note other services may record messages in other files (e.g. sendmail)

• Syslog is also a network service. A common implementation is to forward system info to a common syslog server. See /etc/rsyslog.conf for client /server options

• Logs compressed, ,stored and optionally e-mailed by the logrotate function. Definitions stored in /etc/logrotate.conf and /etc/logrotate.d

Logrotate• Log management for LINUX and UNIX

• Basic config file is /etc/logrotate.conf

• Individual package package config files in/etc/logrotate.d usually configured during package installation

• Each config file specifies logfile list, rotate interval, rotation count, log size, compression options, postrotate command to perform a function after the log has been copied.

Logrotate automation

• UNIX systems require use of a specific CRON job

• LINUX automatically includes logrotate in ANACRON.

• ANACRON is an automatic CRON list created for system functions such as logtotate or tripwire. It is an extension of CRON.

• See /etc files anacron, cron.daily, cron.weekly, cron.monthly. Also /var/spool/anacron

Logwatch

• Default freeware log monitoring tool• Runs in Perl

• Numerous other “pay for play” tools:- Logrobot- Nagios- Logstash- Graybar

Logwatch files• System specific config: /etc/logwatch

• Default config: /usr/share/logwatch/default.conf/

• Distro specific config: /usr/share/logwatch/distro.conf/

• Directories:conf /*.conf, conf/logfiles, conf/services

scripts/services

• Always copy default, distro files to local /etc/logwatch for modification

• Priority sequence: - /etc/logwatch - /usr/share/logwatch/distro.conf- /usr/share/logwatch/default.conf

Security today• Governement regulations:- HIPAA- PCI-DSS- SOX

• No clear text applications – FTP, TELNET, NFS, RCP, RCMD, HTTP

• Restricted access, minimum to do the job

• Most legacy 3rd party apps are now commercial products:- ssh- Nagios- Tripwire- PGPSome have freeware equivalents, but fewer over time.