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25.6. Configuring rsyslog on a Logging Server
The
rsyslog
service provides facilities both for running a logging server and for configuring individual systems to send their log files to the logging server. See Example 25.12, “Reliable Forwarding of Log Messages to a Server” for information on client rsyslog
configuration.
The
rsyslog
service must be installed on the system that you intend to use as a logging server and all systems that will be configured to send logs to it. Rsyslog is installed by default in Red Hat Enterprise Linux 6. If required, to ensure that it is, enter the following command as root
:
~]# yum install rsyslog
The default protocol and port for syslog traffic is
UDP
and 514
, as listed in the /etc/services
file. However, rsyslog
defaults to using TCP
on port 514
. In the configuration file, /etc/rsyslog.conf
, TCP
is indicated by @@
.
Other ports are sometimes used in examples, however SELinux is only configured to allow sending and receiving on the following ports by default:
~]# semanage port -l | grep syslog
syslogd_port_t tcp 6514, 601
syslogd_port_t udp 514, 6514, 601
The semanage
utility is provided as part of the policycoreutils-python package. If required, install the package as follows:
~]# yum install policycoreutils-python
In addition, by default the SELinux type for
rsyslog
, rsyslogd_t
, is configured to permit sending and receiving to the remote shell (rsh
) port with SELinux type rsh_port_t
, which defaults to TCP
on port 514
. Therefore it is not necessary to use semanage
to explicitly permit TCP
on port 514
. For example, to check what SELinux is set to permit on port 514
, enter a command as follows:
~]# semanage port -l | grep 514
output omitted
rsh_port_t tcp 514
syslogd_port_t tcp 6514, 601
syslogd_port_t udp 514, 6514, 601
For more information on SELinux, see Red Hat Enterprise Linux 6 SELinux User Guide.
Perform the steps in the following procedures on the system that you intend to use as your logging server. All steps in these procedure must be made as the
root
user.
Procedure 25.5. Configure SELinux to Permit rsyslog Traffic on a Port
If required to use a new port for
rsyslog
traffic, follow this procedure on the logging server and the clients. For example, to send and receive TCP
traffic on port 10514
, proceed as follows:
~]#
semanage port -a -t syslogd_port_t -p tcp 10514
- Review the SELinux ports by entering the following command:
~]#
semanage port -l | grep syslog
- If the new port was already configured in
/etc/rsyslog.conf
, restartrsyslog
now for the change to take effect:~]#
service rsyslog restart
- Verify which ports
rsyslog
is now listening to:~]#
netstat -tnlp | grep rsyslog
tcp 0 0 0.0.0.0:10514 0.0.0.0:* LISTEN 2528/rsyslogd tcp 0 0 :::10514 :::* LISTEN 2528/rsyslogd
See the
semanage-port(8)
manual page for more information on the semanage port
command.
Procedure 25.6. Configuring The iptables Firewall
Configure the
iptables
firewall to allow incoming rsyslog
traffic. For example, to allow TCP
traffic on port 10514
, proceed as follows:
- Open the
/etc/sysconfig/iptables
file in a text editor. - Add an
INPUT
rule allowingTCP
traffic on port10514
to the file. The new rule must appear before anyINPUT
rules thatREJECT
traffic.-A INPUT -m state --state NEW -m tcp -p tcp --dport 10514 -j ACCEPT
- Save the changes to the
/etc/sysconfig/iptables
file. - Restart the
iptables
service for the firewall changes to take effect.~]#
service iptables restart
Procedure 25.7. Configuring rsyslog to Receive and Sort Remote Log Messages
- Open the
/etc/rsyslog.conf
file in a text editor and proceed as follows:- Add these lines below the modules section but above the
Provides UDP syslog reception
section:# Define templates before the rules that use them ### Per-Host Templates for Remote Systems ### $template TmplAuthpriv, "/var/log/remote/auth/%HOSTNAME%/%PROGRAMNAME:::secpath-replace%.log" $template TmplMsg, "/var/log/remote/msg/%HOSTNAME%/%PROGRAMNAME:::secpath-replace%.log"
- Replace the default
Provides TCP syslog reception
section with the following:# Provides TCP syslog reception $ModLoad imtcp # Adding this ruleset to process remote messages $RuleSet remote1 authpriv.* ?TmplAuthpriv *.info;mail.none;authpriv.none;cron.none ?TmplMsg $RuleSet RSYSLOG_DefaultRuleset #End the rule set by switching back to the default rule set $InputTCPServerBindRuleset remote1 #Define a new input and bind it to the "remote1" rule set $InputTCPServerRun 10514
Save the changes to the/etc/rsyslog.conf
file. - The
rsyslog
service must be running on both the logging server and the systems attempting to log to it.- Use the
service
command to start thersyslog
service.~]#
service rsyslog start
- To ensure the
rsyslog
service starts automatically in future, enter the following command as root:~]#
chkconfig rsyslog on
Your log server is now configured to receive and store log files from the other systems in your environment.
25.6.1. Using The New Template Syntax on a Logging Server
Rsyslog 7 has a number of different templates styles. The string template most closely resembles the legacy format. Reproducing the templates from the example above using the string format would look as follows:
template(name="TmplAuthpriv" type="string" string="/var/log/remote/auth/%HOSTNAME%/%PROGRAMNAME:::secpath-replace%.log" ) template(name="TmplMsg" type="string" string="/var/log/remote/msg/%HOSTNAME%/%PROGRAMNAME:::secpath-replace%.log" )
These templates can also be written in the list format as follows:
template(name="TmplAuthpriv" type="list") { constant(value="/var/log/remote/auth/") property(name="hostname") constant(value="/") property(name="programname" SecurePath="replace") constant(value=".log") } template(name="TmplMsg" type="list") { constant(value="/var/log/remote/msg/") property(name="hostname") constant(value="/") property(name="programname" SecurePath="replace") constant(value=".log") }This template text format might be easier to read for those new to rsyslog and therefore can be easier to adapt as requirements change.
To complete the change to the new syntax, we need to reproduce the module load command, add a rule set, and then bind the rule set to the protocol, port, and ruleset:
module(load="imtcp") ruleset(name="remote1"){ authpriv.* action(type="omfile" DynaFile="TmplAuthpriv") *.info;mail.none;authpriv.none;cron.none action(type="omfile" DynaFile="TmplMsg") } input(type="imtcp" port="10514" ruleset="remote1")